¿Cómo rotar un UIImage 90 grados?

Tengo una UIImageque es UIImageOrientationUp(vertical) que me gustaría a rotar en sentido antihorario en 90 grados (a horizontal). No quiero usar a CGAffineTransform. Quiero que los píxeles de la UIImagereal cambien de posición. Estoy usando un bloque de código (que se muestra a continuación) originalmente destinado a cambiar el tamaño de a UIImagepara hacer esto. Configuré un tamaño de destino como el tamaño actual de UIImagepero recibo un error:

(Error): CGBitmapContextCreate: bytes / fila de datos no válidos: debe ser al menos 1708 para 8 bits enteros / componente, 3 componentes, kCGImageAlphaPremultipliedLast.

(No obtengo un error cada vez que proporciono un tamaño MÁS PEQUEÑO como el tamaño objetivo BTW). ¿Cómo puedo ROTAR mi 90W en sentido UIImagehorario usando solo las funciones gráficas principales y al mismo tiempo preservar el tamaño actual?

-(UIImage*)reverseImageByScalingToSize:(CGSize)targetSize:(UIImage*)anImage
{
    UIImage* sourceImage = anImage; 
    CGFloat targetWidth = targetSize.height;
    CGFloat targetHeight = targetSize.width;

    CGImageRef imageRef = [sourceImage CGImage];
    CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef);
    CGColorSpaceRef colorSpaceInfo = CGImageGetColorSpace(imageRef);

    if (bitmapInfo == kCGImageAlphaNone) {
        bitmapInfo = kCGImageAlphaNoneSkipLast;
    }

    CGContextRef bitmap;

    if (sourceImage.imageOrientation == UIImageOrientationUp || sourceImage.imageOrientation == UIImageOrientationDown) {
        bitmap = CGBitmapContextCreate(NULL, targetHeight, targetWidth, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);

    } else {


        bitmap = CGBitmapContextCreate(NULL, targetWidth, targetHeight, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);

    }       


    if (sourceImage.imageOrientation == UIImageOrientationRight) {
        CGContextRotateCTM (bitmap, radians(90));
        CGContextTranslateCTM (bitmap, 0, -targetHeight);

    } else if (sourceImage.imageOrientation == UIImageOrientationLeft) {
        CGContextRotateCTM (bitmap, radians(-90));
        CGContextTranslateCTM (bitmap, -targetWidth, 0);

    } else if (sourceImage.imageOrientation == UIImageOrientationDown) {
        // NOTHING
    } else if (sourceImage.imageOrientation == UIImageOrientationUp) {
        CGContextRotateCTM (bitmap, radians(90));
        CGContextTranslateCTM (bitmap, 0, -targetHeight);
    }

    CGContextDrawImage(bitmap, CGRectMake(0, 0, targetWidth, targetHeight), imageRef);
    CGImageRef ref = CGBitmapContextCreateImage(bitmap);
    UIImage* newImage = [UIImage imageWithCGImage:ref];

    CGContextRelease(bitmap);
    CGImageRelease(ref);

    return newImage; 
}

¿Qué pasa con algo como:

static inline double radians (double degrees) {return degrees * M_PI/180;}
UIImage* rotate(UIImage* src, UIImageOrientation orientation)
{
    UIGraphicsBeginImageContext(src.size);

    CGContextRef context = UIGraphicsGetCurrentContext();

    if (orientation == UIImageOrientationRight) {
        CGContextRotateCTM (context, radians(90));
    } else if (orientation == UIImageOrientationLeft) {
        CGContextRotateCTM (context, radians(-90));
    } else if (orientation == UIImageOrientationDown) {
        // NOTHING
    } else if (orientation == UIImageOrientationUp) {
        CGContextRotateCTM (context, radians(90));
    }

    [src drawAtPoint:CGPointMake(0, 0)];

    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}

Creo que la forma más fácil (y segura para hilos también) es hacer:

//assume that the image is loaded in landscape mode from disk
UIImage * landscapeImage = [UIImage imageNamed:imgname];
UIImage * portraitImage = [[UIImage alloc] initWithCGImage: landscapeImage.CGImage
                                                     scale: 1.0
                                               orientation: UIImageOrientationRight];

Nota: como Brainware dijo, esto solo modifica los datos de orientación de la imagen: los datos de píxeles no se tocan. Para algunas aplicaciones, esto puede no ser suficiente.

O en Swift:

guard
    let landscapeImage = UIImage(named: "imgname"),
    let landscapeCGImage = landscapeImage.cgImage
else { return }
let portraitImage = UIImage(cgImage: landscapeCGImage, scale: landscapeImage.scale, orientation: .right)

Echa un vistazo al código simple e impresionante de Hardy Macia en: cortando-escalando-y-rotando-uiimages

Solo llama

UIImage *rotatedImage = [originalImage imageRotatedByDegrees:90.0];

Gracias Hardy Macia!

Encabezamiento:

• (UIImage *) imageAtRect: (CGRect) rect;
• (UIImage *) imageByScalingProportionallyToMinimumSize: (CGSize) targetSize;
• (UIImage *) imageByScalingProportionallyToSize: (CGSize) targetSize;
• (UIImage *) imageByScalingToSize: (CGSize) targetSize;
• (UIImage *) imageRotatedByRadians: (CGFloat) radianes;
• (UIImage *) imageRotatedByDegrees: (CGFloat) grados;

Dado que el enlace puede morir, aquí está el código completo

//
//  UIImage-Extensions.h
//
//  Created by Hardy Macia on 7/1/09.
//  Copyright 2009 Catamount Software. All rights reserved.
//
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>

@interface UIImage (CS_Extensions)
- (UIImage *)imageAtRect:(CGRect)rect;
- (UIImage *)imageByScalingProportionallyToMinimumSize:(CGSize)targetSize;
- (UIImage *)imageByScalingProportionallyToSize:(CGSize)targetSize;
- (UIImage *)imageByScalingToSize:(CGSize)targetSize;
- (UIImage *)imageRotatedByRadians:(CGFloat)radians;
- (UIImage *)imageRotatedByDegrees:(CGFloat)degrees;

@end;

//
//  UIImage-Extensions.m
//
//  Created by Hardy Macia on 7/1/09.
//  Copyright 2009 Catamount Software. All rights reserved.
//

#import "UIImage-Extensions.h"

CGFloat DegreesToRadians(CGFloat degrees) {return degrees * M_PI / 180;};
CGFloat RadiansToDegrees(CGFloat radians) {return radians * 180/M_PI;};

@implementation UIImage (CS_Extensions)

-(UIImage *)imageAtRect:(CGRect)rect
{

   CGImageRef imageRef = CGImageCreateWithImageInRect([self CGImage], rect);
   UIImage* subImage = [UIImage imageWithCGImage: imageRef];
   CGImageRelease(imageRef);

   return subImage;

}

- (UIImage *)imageByScalingProportionallyToMinimumSize:(CGSize)targetSize {

   UIImage *sourceImage = self;
   UIImage *newImage = nil;

   CGSize imageSize = sourceImage.size;
   CGFloat width = imageSize.width;
   CGFloat height = imageSize.height;

   CGFloat targetWidth = targetSize.width;
   CGFloat targetHeight = targetSize.height;

   CGFloat scaleFactor = 0.0;
   CGFloat scaledWidth = targetWidth;
   CGFloat scaledHeight = targetHeight;

   CGPoint thumbnailPoint = CGPointMake(0.0,0.0);

   if (CGSizeEqualToSize(imageSize, targetSize) == NO) {

      CGFloat widthFactor = targetWidth / width;
      CGFloat heightFactor = targetHeight / height;

      if (widthFactor > heightFactor) 
         scaleFactor = widthFactor;
      else
         scaleFactor = heightFactor;

      scaledWidth  = width * scaleFactor;
      scaledHeight = height * scaleFactor;

      // center the image

      if (widthFactor > heightFactor) {
         thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5; 
      } else if (widthFactor < heightFactor) {
         thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
      }
   }


   // this is actually the interesting part:

   UIGraphicsBeginImageContext(targetSize);

   CGRect thumbnailRect = CGRectZero;
   thumbnailRect.origin = thumbnailPoint;
   thumbnailRect.size.width  = scaledWidth;
   thumbnailRect.size.height = scaledHeight;

   [sourceImage drawInRect:thumbnailRect];

   newImage = UIGraphicsGetImageFromCurrentImageContext();
   UIGraphicsEndImageContext();

   if(newImage == nil) NSLog(@"could not scale image");


   return newImage ;
}


- (UIImage *)imageByScalingProportionallyToSize:(CGSize)targetSize {

   UIImage *sourceImage = self;
   UIImage *newImage = nil;

   CGSize imageSize = sourceImage.size;
   CGFloat width = imageSize.width;
   CGFloat height = imageSize.height;

   CGFloat targetWidth = targetSize.width;
   CGFloat targetHeight = targetSize.height;

   CGFloat scaleFactor = 0.0;
   CGFloat scaledWidth = targetWidth;
   CGFloat scaledHeight = targetHeight;

   CGPoint thumbnailPoint = CGPointMake(0.0,0.0);

   if (CGSizeEqualToSize(imageSize, targetSize) == NO) {

      CGFloat widthFactor = targetWidth / width;
      CGFloat heightFactor = targetHeight / height;

      if (widthFactor < heightFactor) 
         scaleFactor = widthFactor;
      else
         scaleFactor = heightFactor;

      scaledWidth  = width * scaleFactor;
      scaledHeight = height * scaleFactor;

      // center the image

      if (widthFactor < heightFactor) {
         thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5; 
      } else if (widthFactor > heightFactor) {
         thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
      }
   }


   // this is actually the interesting part:

   UIGraphicsBeginImageContext(targetSize);

   CGRect thumbnailRect = CGRectZero;
   thumbnailRect.origin = thumbnailPoint;
   thumbnailRect.size.width  = scaledWidth;
   thumbnailRect.size.height = scaledHeight;

   [sourceImage drawInRect:thumbnailRect];

   newImage = UIGraphicsGetImageFromCurrentImageContext();
   UIGraphicsEndImageContext();

   if(newImage == nil) NSLog(@"could not scale image");


   return newImage ;
}


- (UIImage *)imageByScalingToSize:(CGSize)targetSize {

   UIImage *sourceImage = self;
   UIImage *newImage = nil;

   //   CGSize imageSize = sourceImage.size;
   //   CGFloat width = imageSize.width;
   //   CGFloat height = imageSize.height;

   CGFloat targetWidth = targetSize.width;
   CGFloat targetHeight = targetSize.height;

   //   CGFloat scaleFactor = 0.0;
   CGFloat scaledWidth = targetWidth;
   CGFloat scaledHeight = targetHeight;

   CGPoint thumbnailPoint = CGPointMake(0.0,0.0);

   // this is actually the interesting part:

   UIGraphicsBeginImageContext(targetSize);

   CGRect thumbnailRect = CGRectZero;
   thumbnailRect.origin = thumbnailPoint;
   thumbnailRect.size.width  = scaledWidth;
   thumbnailRect.size.height = scaledHeight;

   [sourceImage drawInRect:thumbnailRect];

   newImage = UIGraphicsGetImageFromCurrentImageContext();
   UIGraphicsEndImageContext();

   if(newImage == nil) NSLog(@"could not scale image");


   return newImage ;
}


- (UIImage *)imageRotatedByRadians:(CGFloat)radians
{
   return [self imageRotatedByDegrees:RadiansToDegrees(radians)];
}

- (UIImage *)imageRotatedByDegrees:(CGFloat)degrees 
{   
   // calculate the size of the rotated view's containing box for our drawing space
   UIView *rotatedViewBox = [[UIView alloc] initWithFrame:CGRectMake(0,0,self.size.width, self.size.height)];
   CGAffineTransform t = CGAffineTransformMakeRotation(DegreesToRadians(degrees));
   rotatedViewBox.transform = t;
   CGSize rotatedSize = rotatedViewBox.frame.size;
   [rotatedViewBox release];

   // Create the bitmap context
   UIGraphicsBeginImageContext(rotatedSize);
   CGContextRef bitmap = UIGraphicsGetCurrentContext();

   // Move the origin to the middle of the image so we will rotate and scale around the center.
   CGContextTranslateCTM(bitmap, rotatedSize.width/2, rotatedSize.height/2);

   //   // Rotate the image context
   CGContextRotateCTM(bitmap, DegreesToRadians(degrees));

   // Now, draw the rotated/scaled image into the context
   CGContextScaleCTM(bitmap, 1.0, -1.0);
   CGContextDrawImage(bitmap, CGRectMake(-self.size.width / 2, -self.size.height / 2, self.size.width, self.size.height), [self CGImage]);

   UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
   UIGraphicsEndImageContext();
   return newImage;

}

@end;

Por extraño que parezca, el siguiente código resolvió el problema para mí:

+ (UIImage*)unrotateImage:(UIImage*)image {
    CGSize size = image.size;
    UIGraphicsBeginImageContext(size);
    [image drawInRect:CGRectMake(0,0,size.width ,size.height)];
    UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return newImage;
}

Una función de rotación segura para subprocesos es la siguiente (funciona mucho mejor):

-(UIImage*)imageByRotatingImage:(UIImage*)initImage fromImageOrientation:(UIImageOrientation)orientation
{
CGImageRef imgRef = initImage.CGImage;

CGFloat width = CGImageGetWidth(imgRef);
CGFloat height = CGImageGetHeight(imgRef);

CGAffineTransform transform = CGAffineTransformIdentity;
CGRect bounds = CGRectMake(0, 0, width, height);
CGSize imageSize = CGSizeMake(CGImageGetWidth(imgRef), CGImageGetHeight(imgRef));
CGFloat boundHeight;
UIImageOrientation orient = orientation;
switch(orient) {

    case UIImageOrientationUp: //EXIF = 1
        return initImage;
        break;

    case UIImageOrientationUpMirrored: //EXIF = 2
        transform = CGAffineTransformMakeTranslation(imageSize.width, 0.0);
        transform = CGAffineTransformScale(transform, -1.0, 1.0);
        break;

    case UIImageOrientationDown: //EXIF = 3
        transform = CGAffineTransformMakeTranslation(imageSize.width, imageSize.height);
        transform = CGAffineTransformRotate(transform, M_PI);
        break;

    case UIImageOrientationDownMirrored: //EXIF = 4
        transform = CGAffineTransformMakeTranslation(0.0, imageSize.height);
        transform = CGAffineTransformScale(transform, 1.0, -1.0);
        break;

    case UIImageOrientationLeftMirrored: //EXIF = 5
        boundHeight = bounds.size.height;
        bounds.size.height = bounds.size.width;
        bounds.size.width = boundHeight;
        transform = CGAffineTransformMakeTranslation(imageSize.height, imageSize.width);
        transform = CGAffineTransformScale(transform, -1.0, 1.0);
        transform = CGAffineTransformRotate(transform, 3.0 * M_PI / 2.0);
        break;

    case UIImageOrientationLeft: //EXIF = 6
        boundHeight = bounds.size.height;
        bounds.size.height = bounds.size.width;
        bounds.size.width = boundHeight;
        transform = CGAffineTransformMakeTranslation(0.0, imageSize.width);
        transform = CGAffineTransformRotate(transform, 3.0 * M_PI / 2.0);
        break;

    case UIImageOrientationRightMirrored: //EXIF = 7
        boundHeight = bounds.size.height;
        bounds.size.height = bounds.size.width;
        bounds.size.width = boundHeight;
        transform = CGAffineTransformMakeScale(-1.0, 1.0);
        transform = CGAffineTransformRotate(transform, M_PI / 2.0);
        break;

    case UIImageOrientationRight: //EXIF = 8
        boundHeight = bounds.size.height;
        bounds.size.height = bounds.size.width;
        bounds.size.width = boundHeight;
        transform = CGAffineTransformMakeTranslation(imageSize.height, 0.0);
        transform = CGAffineTransformRotate(transform, M_PI / 2.0);
        break;

    default:
        [NSException raise:NSInternalInconsistencyException format:@"Invalid image orientation"];

}
// Create the bitmap context
CGContextRef    context = NULL;
void *          bitmapData;
int             bitmapByteCount;
int             bitmapBytesPerRow;

// Declare the number of bytes per row. Each pixel in the bitmap in this
// example is represented by 4 bytes; 8 bits each of red, green, blue, and
// alpha.
bitmapBytesPerRow   = (bounds.size.width * 4);
bitmapByteCount     = (bitmapBytesPerRow * bounds.size.height);
bitmapData = malloc( bitmapByteCount );
if (bitmapData == NULL)
{
    return nil;
}

// Create the bitmap context. We want pre-multiplied ARGB, 8-bits
// per component. Regardless of what the source image format is
// (CMYK, Grayscale, and so on) it will be converted over to the format
// specified here by CGBitmapContextCreate.
CGColorSpaceRef colorspace = CGImageGetColorSpace(imgRef);
context = CGBitmapContextCreate (bitmapData,bounds.size.width,bounds.size.height,8,bitmapBytesPerRow,
                                 colorspace, kCGBitmapAlphaInfoMask & kCGImageAlphaPremultipliedLast);

if (context == NULL)
    // error creating context
    return nil;

CGContextScaleCTM(context, -1.0, -1.0);
CGContextTranslateCTM(context, -bounds.size.width, -bounds.size.height);

CGContextConcatCTM(context, transform);

// Draw the image to the bitmap context. Once we draw, the memory
// allocated for the context for rendering will then contain the
// raw image data in the specified color space.
CGContextDrawImage(context, CGRectMake(0,0,width, height), imgRef);

CGImageRef imgRef2 = CGBitmapContextCreateImage(context);
CGContextRelease(context);
free(bitmapData);
UIImage * image = [UIImage imageWithCGImage:imgRef2 scale:initImage.scale orientation:UIImageOrientationUp];
CGImageRelease(imgRef2);
return image;
}

Tuve problemas con todo lo anterior, incluida la respuesta aprobada. Convertí la categoría de Hardy nuevamente en un método ya que todo lo que quería era rotar una imagen. Aquí está el código y el uso:

- (UIImage *)imageRotatedByDegrees:(UIImage*)oldImage deg:(CGFloat)degrees{
// calculate the size of the rotated view's containing box for our drawing space
UIView *rotatedViewBox = [[UIView alloc] initWithFrame:CGRectMake(0,0,oldImage.size.width, oldImage.size.height)];
CGAffineTransform t = CGAffineTransformMakeRotation(degrees * M_PI / 180);
rotatedViewBox.transform = t;
CGSize rotatedSize = rotatedViewBox.frame.size;
// Create the bitmap context
UIGraphicsBeginImageContext(rotatedSize);
CGContextRef bitmap = UIGraphicsGetCurrentContext();

// Move the origin to the middle of the image so we will rotate and scale around the center.
CGContextTranslateCTM(bitmap, rotatedSize.width/2, rotatedSize.height/2);

//   // Rotate the image context
CGContextRotateCTM(bitmap, (degrees * M_PI / 180));

// Now, draw the rotated/scaled image into the context
CGContextScaleCTM(bitmap, 1.0, -1.0);
CGContextDrawImage(bitmap, CGRectMake(-oldImage.size.width / 2, -oldImage.size.height / 2, oldImage.size.width, oldImage.size.height), [oldImage CGImage]);

UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}

Y el uso:

UIImage *image2 = [self imageRotatedByDegrees:image deg:90];

Gracias Hardy!

Girar la imagen 90 grados (en sentido horario / antihorario)

Llamada de función -

 UIImage *rotatedImage = [self rotateImage:originalImage clockwise:YES];

Implementación:

- (UIImage*)rotateImage:(UIImage*)sourceImage clockwise:(BOOL)clockwise
  {
    CGSize size = sourceImage.size;
    UIGraphicsBeginImageContext(CGSizeMake(size.height, size.width));
    [[UIImage imageWithCGImage:[sourceImage CGImage]
                         scale:1.0
                   orientation:clockwise ? UIImageOrientationRight : UIImageOrientationLeft]
                   drawInRect:CGRectMake(0,0,size.height ,size.width)];

   UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
   UIGraphicsEndImageContext();

   return newImage;
  }

Si desea agregar un botón de rotación de fotos que seguirá girando la foto en incrementos de 90 grados, aquí tiene. ( finalImagees un UIImage que ya se ha creado en otro lugar).

- (void)rotatePhoto {
    UIImage *rotatedImage;

    if (finalImage.imageOrientation == UIImageOrientationRight)
        rotatedImage = [[UIImage alloc] initWithCGImage: finalImage.CGImage
                                              scale: 1.0
                                        orientation: UIImageOrientationDown];
    else if (finalImage.imageOrientation == UIImageOrientationDown)
        rotatedImage = [[UIImage alloc] initWithCGImage: finalImage.CGImage
                                              scale: 1.0
                                        orientation: UIImageOrientationLeft];
    else if (finalImage.imageOrientation == UIImageOrientationLeft)
        rotatedImage = [[UIImage alloc] initWithCGImage: finalImage.CGImage
                                              scale: 1.0
                                        orientation: UIImageOrientationUp];
    else
        rotatedImage = [[UIImage alloc] initWithCGImage: finalImage.CGImage
                                                     scale: 1.0
                                               orientation: UIImageOrientationRight];
    finalImage = rotatedImage;
}

Sencillo. Simplemente cambie la bandera de orientación de la imagen.

UIImage *oldImage = [UIImage imageNamed:@"whatever.jpg"];
UIImageOrientation newOrientation;
switch (oldImage.imageOrientation) {
    case UIImageOrientationUp:
        newOrientation = UIImageOrientationLandscapeLeft;
        break;
    case UIImageOrientationLandscapeLeft:
        newOrientation = UIImageOrientationDown;
        break;
    case UIImageOrientationDown:
        newOrientation = UIImageOrientationLandscapeRight;
        break;
    case UIImageOrientationLandscapeRight:
        newOrientation = UIImageOrientationUp;
        break;
    // you can also handle mirrored orientations similarly ...
}
UIImage *rotatedImage = [UIImage imageWithCGImage:oldImage.CGImage scale:1.0f orientation:newOrientation];

Aquí hay una extensión Swift de UIImage que rota la imagen en cualquier ángulo arbitrario. Utilizar de esta manera: let rotatedImage = image.rotated(byDegrees: degree). Utilicé el código Objective-C en una de las otras respuestas y eliminé algunas líneas que incorrectamente (cosas de caja rotadas) y lo convertí en una extensión para UIImage.

extension UIImage {

func rotate(byDegrees degree: Double) -> UIImage {
    let radians = CGFloat(degree*M_PI)/180.0 as CGFloat
    let rotatedSize = self.size
    let scale = UIScreen.mainScreen().scale
    UIGraphicsBeginImageContextWithOptions(rotatedSize, false, scale)
    let bitmap = UIGraphicsGetCurrentContext()
    CGContextTranslateCTM(bitmap, rotatedSize.width / 2, rotatedSize.height / 2);
    CGContextRotateCTM(bitmap, radians);
    CGContextScaleCTM(bitmap, 1.0, -1.0);
    CGContextDrawImage(bitmap, CGRectMake(-self.size.width / 2, -self.size.height / 2 , self.size.width, self.size.height), self.CGImage );
    let newImage = UIGraphicsGetImageFromCurrentImageContext()

    return newImage
}
}

Extensión Swift 3 UIImage:

func fixOrientation() -> UIImage {

    // No-op if the orientation is already correct
    if ( self.imageOrientation == .up ) {
        return self;
    }

    // We need to calculate the proper transformation to make the image upright.
    // We do it in 2 steps: Rotate if Left/Right/Down, and then flip if Mirrored.
    var transform: CGAffineTransform = .identity

    if ( self.imageOrientation == .down || self.imageOrientation == .downMirrored ) {
        transform = transform.translatedBy(x: self.size.width, y: self.size.height)
        transform = transform.rotated(by: .pi)
    }

    if ( self.imageOrientation == .left || self.imageOrientation == .leftMirrored ) {
        transform = transform.translatedBy(x: self.size.width, y: 0)
        transform = transform.rotated(by: .pi/2)
    }

    if ( self.imageOrientation == .right || self.imageOrientation == .rightMirrored ) {
        transform = transform.translatedBy(x: 0, y: self.size.height);
        transform = transform.rotated(by: -.pi/2);
    }

    if ( self.imageOrientation == .upMirrored || self.imageOrientation == .downMirrored ) {
        transform = transform.translatedBy(x: self.size.width, y: 0)
        transform = transform.scaledBy(x: -1, y: 1)
    }

    if ( self.imageOrientation == .leftMirrored || self.imageOrientation == .rightMirrored ) {
        transform = transform.translatedBy(x: self.size.height, y: 0);
        transform = transform.scaledBy(x: -1, y: 1);
    }

    // Now we draw the underlying CGImage into a new context, applying the transform
    // calculated above.
    let ctx: CGContext = CGContext(data: nil, width: Int(self.size.width), height: Int(self.size.height),
                                   bitsPerComponent: self.cgImage!.bitsPerComponent, bytesPerRow: 0,
                                   space: self.cgImage!.colorSpace!,
                                   bitmapInfo: self.cgImage!.bitmapInfo.rawValue)!;

    ctx.concatenate(transform)

    if ( self.imageOrientation == .left ||
        self.imageOrientation == .leftMirrored ||
        self.imageOrientation == .right ||
        self.imageOrientation == .rightMirrored ) {
        ctx.draw(self.cgImage!, in: CGRect(x: 0.0,y: 0.0,width: self.size.height,height: self.size.width))
    } else {
        ctx.draw(self.cgImage!, in: CGRect(x: 0.0,y: 0.0,width: self.size.width,height: self.size.height))
    }

    // And now we just create a new UIImage from the drawing context and return it
    return UIImage(cgImage: ctx.makeImage()!)
}

Versión Swift 4.2 de la respuesta de RawMean :

extension UIImage {

func rotated(byDegrees degree: Double) -> UIImage {
    let radians = CGFloat(degree * .pi) / 180.0 as CGFloat
    let rotatedSize = self.size
    let scale = UIScreen.main.scale
    UIGraphicsBeginImageContextWithOptions(rotatedSize, false, scale)
    let bitmap = UIGraphicsGetCurrentContext()
    bitmap?.translateBy(x: rotatedSize.width / 2, y: rotatedSize.height / 2)
    bitmap?.rotate(by: radians)
    bitmap?.scaleBy(x: 1.0, y: -1.0)
    bitmap?.draw(
        self.cgImage!,
        in: CGRect.init(x: -self.size.width / 2, y: -self.size.height / 2 , width: self.size.width, height: self.size.height))
    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext() // this is needed
    return newImage!
}

}

Intento este código, funciona, y tomé de http://www.catamount.com/blog/1015/uiimage-extensions-for-cutting-scaling-and-rotating-uiimages/

+ (UIImage *)rotateImage:(UIImage*)src byRadian:(CGFloat)radian
{
    // calculate the size of the rotated view's containing box for our drawing space
    UIView *rotatedViewBox = [[UIView alloc] initWithFrame:CGRectMake(0,0, src.size.width, src.size.height)];
    CGAffineTransform t = CGAffineTransformMakeRotation(radian);
    rotatedViewBox.transform = t;
    CGSize rotatedSize = rotatedViewBox.frame.size;

    // Create the bitmap context
    UIGraphicsBeginImageContext(rotatedSize);
    CGContextRef bitmap = UIGraphicsGetCurrentContext();

    // Move the origin to the middle of the image so we will rotate and scale around the center.
    CGContextTranslateCTM(bitmap, rotatedSize.width/2, rotatedSize.height/2);

    //   // Rotate the image context
    CGContextRotateCTM(bitmap, radian);

    // Now, draw the rotated/scaled image into the context
    CGContextScaleCTM(bitmap, 1.0, -1.0);
    CGContextDrawImage(bitmap, CGRectMake(-src.size.width / 2, -src.size.height / 2, src.size.width, src.size.height), [src CGImage]);

    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;
}

Pequeños cambios a las otras respuestas que se basan en el código de Hardy Macia. No es necesario crear un UIViewobjeto completo simplemente para calcular el rectángulo delimitador de la imagen girada. Simplemente aplique una transformación de rotación al rectángulo de la imagen usando CGRectApplyAffineTransform.

static CGFloat DegreesToRadians(CGFloat degrees) {return degrees * M_PI / 180;}
static CGFloat RadiansToDegrees(CGFloat radians) {return radians * 180/M_PI;}


- (CGSize)rotatedImageSize:(CGFloat)degrees
{
    CGAffineTransform t = CGAffineTransformMakeRotation(DegreesToRadians(degrees));
    CGRect originalImageRect = CGRectMake(0, 0, self.size.width, self.size.height);
    CGRect rotatedImageRect = CGRectApplyAffineTransform(originalImageRect, t);
    CGSize rotatedSize = rotatedImageRect.size;

    return rotatedSize;
}

- (UIImage*)imageRotatedByDegrees:(CGFloat)degrees
{
    // calculate the size of the rotated view's containing box for our drawing space
    CGSize rotatedSize = [self rotatedImageSize:degrees];

    // Create the bitmap context
    UIGraphicsBeginImageContext(rotatedSize);
    CGContextRef bitmap = UIGraphicsGetCurrentContext();

    // Move the origin to the middle of the image so we will rotate and scale around the center.
    CGContextTranslateCTM(bitmap, rotatedSize.width/2, rotatedSize.height/2);

    //   // Rotate the image context
    CGContextRotateCTM(bitmap, DegreesToRadians(degrees));

    // Now, draw the rotated/scaled image into the context
    CGContextScaleCTM(bitmap, 1.0, -1.0);
    CGContextDrawImage(bitmap, CGRectMake(-self.size.width / 2, -self.size.height / 2, self.size.width, self.size.height), [self CGImage]);

    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;
}

"tint uiimage grayscale" parece ser el Google-Fu apropiado para este

enseguida me sale:

https://discussions.apple.com/message/8104516?messageID=8104516ꩄ

https://discussions.apple.com/thread/2751445?start=0&tstart=0

¿Cómo teñiría una imagen mediante programación en el iPhone?

Me gusta la simple elegancia de Peter Sarnowskila respuesta, pero puede causar problemas cuando no puede confiar en EXIFmetadatos y similares. En situaciones en las que necesita rotar los datos de la imagen real , recomendaría algo como esto:

- (UIImage *)rotateImage:(UIImage *) img
{
    CGSize imgSize = [img size];
    UIGraphicsBeginImageContext(imgSize);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextRotateCTM(context, M_PI_2);
    CGContextTranslateCTM(context, 0, -640);
    [img drawInRect:CGRectMake(0, 0, imgSize.height, imgSize.width)];
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;
}

El código anterior toma una imagen cuya orientación es Landscape(no recuerdo si es Landscape Lefto Landscape Right) y la gira Portrait. Es un ejemplo que puede modificarse según sus necesidades.

Los argumentos clave con los que tendrías que jugar son CGContextRotateCTM(context, M_PI_2)dónde decides cuánto quieres rotar, pero luego debes asegurarte de que la imagen todavía se dibuja en la pantalla usandoCGContextTranslateCTM(context, 0, -640) . Esta última parte es bastante importante para asegurarse de ver la imagen y no una pantalla en blanco.

Para obtener más información, consulte la fuente .

resize-a-uiimage-the-right-way explica algunos de los problemas que tienen muchos ejemplos de código para hacer esto, y tiene algunos fragmentos de código para ayudar a lidiar con UIImages: el método de ayuda privada en UIImage + resize.m acepta una transformación para permitir rotación, por lo que solo debe exponer eso como una interfaz pública.

// Returns a copy of the image that has been transformed using the given affine transform and scaled to the new size
// The new image's orientation will be UIImageOrientationUp, regardless of the current image's orientation
// If the new size is not integral, it will be rounded up
- (UIImage *)resizedImage:(CGSize)newSize
                transform:(CGAffineTransform)transform
           drawTransposed:(BOOL)transpose
     interpolationQuality:(CGInterpolationQuality)quality {
    CGRect newRect = CGRectIntegral(CGRectMake(0, 0, newSize.width, newSize.height));
    CGRect transposedRect = CGRectMake(0, 0, newRect.size.height, newRect.size.width);
    CGImageRef imageRef = self.CGImage;

    // Build a context that's the same dimensions as the new size
    CGContextRef bitmap = CGBitmapContextCreate(NULL,
                                                newRect.size.width,
                                                newRect.size.height,
                                                CGImageGetBitsPerComponent(imageRef),
                                                0,
                                                CGImageGetColorSpace(imageRef),
                                                CGImageGetBitmapInfo(imageRef));

    // Rotate and/or flip the image if required by its orientation
    CGContextConcatCTM(bitmap, transform);

    // Set the quality level to use when rescaling
    CGContextSetInterpolationQuality(bitmap, quality);

    // Draw into the context; this scales the image
    CGContextDrawImage(bitmap, transpose ? transposedRect : newRect, imageRef);

    // Get the resized image from the context and a UIImage
    CGImageRef newImageRef = CGBitmapContextCreateImage(bitmap);
    UIImage *newImage = [UIImage imageWithCGImage:newImageRef];

    // Clean up
    CGContextRelease(bitmap);
    CGImageRelease(newImageRef);

    return newImage;
}

Esta es la licencia de ese archivo:

// Created by Trevor Harmon on 8/5/09.
// Free for personal or commercial use, with or without modification.
// No warranty is expressed or implied.

Hay una categoría de UIImage extremadamente eficiente llamada NYXImagesKit. Utiliza vDSP, CoreImage y vImage para ser lo más rápido posible. Tiene una categoría UIImage + Rotating que me salvó el día :)

https://github.com/Nyx0uf/NYXImagesKit

Para Swift: Aquí hay una extensión simple para UIImage:

//ImageRotation.swift

import UIKit

extension UIImage {  
    public func imageRotatedByDegrees(degrees: CGFloat, flip: Bool) -> UIImage {
        let radiansToDegrees: (CGFloat) -> CGFloat = {
            return $0 * (180.0 / CGFloat(M_PI))
        }
        let degreesToRadians: (CGFloat) -> CGFloat = {
            return $0 / 180.0 * CGFloat(M_PI)
        }

        // calculate the size of the rotated view's containing box for our drawing space
        let rotatedViewBox = UIView(frame: CGRect(origin: CGPointZero, size: size))
        let t = CGAffineTransformMakeRotation(degreesToRadians(degrees));
        rotatedViewBox.transform = t
        let rotatedSize = rotatedViewBox.frame.size

        // Create the bitmap context
        UIGraphicsBeginImageContext(rotatedSize)
        let bitmap = UIGraphicsGetCurrentContext()

        // Move the origin to the middle of the image so we will rotate and scale around the center.
        CGContextTranslateCTM(bitmap, rotatedSize.width / 2.0, rotatedSize.height / 2.0);

        //   // Rotate the image context
        CGContextRotateCTM(bitmap, degreesToRadians(degrees));

        // Now, draw the rotated/scaled image into the context
        var yFlip: CGFloat

        if(flip){
            yFlip = CGFloat(-1.0)
        } else {
            yFlip = CGFloat(1.0)
        }

        CGContextScaleCTM(bitmap, yFlip, -1.0)
        CGContextDrawImage(bitmap, CGRectMake(-size.width / 2, -size.height / 2, size.width, size.height), CGImage)

        let newImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return newImage
    }
}

( Fuente )

Úselo con:

rotatedPhoto = rotatedPhoto?.imageRotatedByDegrees(90, flip: false) 

El primero rotará una imagen y la volteará si flip se establece en verdadero.