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copied!<p>Check out the simple and awesome code of Hardy Macia at: <a href="http://www.catamount.com/blog/1015/uiimage-extensions-for-cutting-scaling-and-rotating-uiimages/" rel="noreferrer">cutting-scaling-and-rotating-uiimages</a></p> <p>Just call</p> <pre><code>UIImage *rotatedImage = [originalImage imageRotatedByDegrees:90.0]; </code></pre> <p>Thanks Hardy Macia!</p> <p>Header:</p> <ul> <li><strong>(UIImage *)imageAtRect:(CGRect)rect;</strong></li> <li><strong>(UIImage *)imageByScalingProportionallyToMinimumSize:(CGSize)targetSize;</strong></li> <li><strong>(UIImage *)imageByScalingProportionallyToSize:(CGSize)targetSize;</strong></li> <li><strong>(UIImage *)imageByScalingToSize:(CGSize)targetSize;</strong></li> <li><strong>(UIImage *)imageRotatedByRadians:(CGFloat)radians;</strong></li> <li><strong>(UIImage *)imageRotatedByDegrees:(CGFloat)degrees;</strong></li> </ul> <p>Since the link may die, here's the complete code</p> <pre><code>// // 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; </code></pre>

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