一有用的 UIImage 扩展，支持（等比例）放大和旋转可在许多 App 中使用。 UIImage-Extensions.h #import <Foundation/Foundation.h> #import <UIKit/UIKit.h> CGFloat DegreesToRadians(CGFloat degrees); CGFloat RadiansToDegrees(CGFloat radians); @interface UIImage (JQ_Extensions) - (UIImage *)imageAtRect:(CGRect)rect;- (UIImage *)imageByScalingProportionallyToSize:(CGSize)targetSize; - (UIImage *)imageByScalingToSize:(CGSize)targetSize; - (UIImage *)imageRotatedByRadians:(CGFloat)radians; - (UIImage *)imageRotatedByDegrees:(CGFloat)degrees; - (UIImage *)addImage:(UIImage *)image1 toImage:(UIImage *)image2; [objc] view plaincopyprint? - (UIImage *) imageWithBackgroundColor:(UIColor *)bgColor shadeAlpha1:(CGFloat)alpha1 shadeAlpha2:(CGFloat)alpha2 shadeAlpha3:(CGFloat)alpha3 shadowColor:(UIColor *)shadowColor shadowOffset:(CGSize)shadowOffset shadowBlur:(CGFloat)shadowBlur; - (UIImage *)imageWithShadowColor:(UIColor *)shadowColor shadowOffset:(CGSize)shadowOffset shadowBlur:(CGFloat)shadowBlur;<br> - (UIImage *)imageByApplyingAlpha:(CGFloat)alpha; - ( void ) saveToAlbumWithMetadata: ( NSDictionary * ) metadata customAlbumName: ( NSString * ) customAlbumName completionBlock: ( void ( ^ )( void )) completionBlock failureBlock: ( void ( ^ )( NSError * error )) failureBlock @end; UIImage-Extensions.m #import "UIImage-Extensions.h" CGFloat DegreesToRadians(CGFloat degrees) {return degrees * M_PI / 180;}; CGFloat RadiansToDegrees(CGFloat radians) {return radians * 180/M_PI;}; @implementation UIImage (JQ_Extensions) -(UIImage *)imageAtRect:(CGRect)rect { CGImageRef imageRef = CGImageCreateWithImageInRect([self CGImage], rect); UIImage* subImage = [UIImage imageWithCGImage: imageRef]; CGImageRelease(imageRef); return subImage; } - (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; } // Combine two UIImages [objc] view plaincopyprint? - (UIImage *)addImage:(UIImage *)image1 toImage:(UIImage *)image2 { UIGraphicsBeginImageContext(image2.size); // Draw image1 [image1 drawInRect:CGRectMake(0, 0, image1.size.width, image1.size.height)]; // Draw image2 [image2 drawInRect:CGRectMake(0, 0, image2.size.width, image2.size.height)]; UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext();<br> return resultingImage; } [objc] view plaincopyprint? - (UIImage *) imageWithBackgroundColor:(UIColor *)bgColor shadeAlpha1:(CGFloat)alpha1 shadeAlpha2:(CGFloat)alpha2 shadeAlpha3:(CGFloat)alpha3 shadowColor:(UIColor *)shadowColor shadowOffset:(CGSize)shadowOffset shadowBlur:(CGFloat)shadowBlur { UIImage *image = self; CGColorRef cgColor = [bgColor CGColor]; CGColorRef cgShadowColor = [shadowColor CGColor]; CGFloat components[16] = {1,1,1,alpha1,1,1,1,alpha1,1,1,1,alpha2,1,1,1,alpha3}; CGFloat locations[4] = {0,0.5,0.6,1}; CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); CGGradientRef colorGradient = CGGradientCreateWithColorComponents(colorSpace, components, locations, (size_t)4); CGRect contextRect; contextRect.origin.x = 0.0f; contextRect.origin.y = 0.0f; contextRect.size = [image size]; //contextRect.size = CGSizeMake([image size].width+5,[image size].height+5); // Retrieve source image and begin image context UIImage *itemImage = image; CGSize itemImageSize = [itemImage size]; CGPoint itemImagePosition; itemImagePosition.x = ceilf((contextRect.size.width - itemImageSize.width) / 2); itemImagePosition.y = ceilf((contextRect.size.height - itemImageSize.height) / 2); UIGraphicsBeginImageContext(contextRect.size); CGContextRef c = UIGraphicsGetCurrentContext(); // Setup shadow CGContextSetShadowWithColor(c, shadowOffset, shadowBlur, cgShadowColor); // Setup transparency layer and clip to mask CGContextBeginTransparencyLayer(c, NULL); CGContextScaleCTM(c, 1.0, -1.0); CGContextClipToMask(c, CGRectMake(itemImagePosition.x, -itemImagePosition.y, itemImageSize.width, -itemImageSize.height), [itemImage CGImage]); // Fill and end the transparency layer CGContextSetFillColorWithColor(c, cgColor); contextRect.size.height = -contextRect.size.height; CGContextFillRect(c, contextRect); CGContextDrawLinearGradient(c, colorGradient,CGPointZero,CGPointMake(contextRect.size.width*1.0/4.0,contextRect.size.height),0); CGContextEndTransparencyLayer(c); //CGPointMake(contextRect.size.width*3.0/4.0, 0) // Set selected image and end context UIImage *resultImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); CGColorSpaceRelease(colorSpace); CGGradientRelease(colorGradient); return resultImage; } - (UIImage *)imageWithShadowColor:(UIColor *)shadowColor shadowOffset:(CGSize)shadowOffset shadowBlur:(CGFloat)shadowBlur { CGColorRef cgShadowColor = [shadowColor CGColor]; CGColorSpaceRef colourSpace = CGColorSpaceCreateDeviceRGB(); CGContextRef shadowContext = CGBitmapContextCreate(NULL, self.size.width, self.size.height, CGImageGetBitsPerComponent(self.CGImage), 0, colourSpace, kCGImageAlphaPremultipliedLast); CGColorSpaceRelease(colourSpace); // Setup shadow CGContextSetShadowWithColor(shadowContext, shadowOffset, shadowBlur, cgShadowColor); CGRect drawRect = CGRectMake(-shadowBlur, -shadowBlur, self.size.width + shadowBlur, self.size.height + shadowBlur); CGContextDrawImage(shadowContext, drawRect, self.CGImage); CGImageRef shadowedCGImage = CGBitmapContextCreateImage(shadowContext); CGContextRelease(shadowContext); UIImage * shadowedImage = [UIImage imageWithCGImage:shadowedCGImage]; CGImageRelease(shadowedCGImage); return shadowedImage; } - (UIImage *)imageByApplyingAlpha:(CGFloat)alpha { UIGraphicsBeginImageContextWithOptions(self.size, NO, 0.0f); CGContextRef ctx = UIGraphicsGetCurrentContext(); CGRect area = CGRectMake(0, 0, self.size.width, self.size.height); CGContextScaleCTM(ctx, 1, -1); CGContextTranslateCTM(ctx, 0, -area.size.height); CGContextSetBlendMode(ctx, kCGBlendModeMultiply); CGContextSetAlpha(ctx, alpha); CGContextDrawImage(ctx, area, self.CGImage); UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return newImage; } - ( void ) saveToAlbumWithMetadata: ( NSDictionary * ) metadata customAlbumName: ( NSString * ) customAlbumName completionBlock: ( void ( ^ )( void )) completionBlock failureBlock: ( void ( ^ )( NSError * error )) failureBlock { NSData * imageData = UIImagePNGRepresentation ( self ); ALAssetsLibrary * assetsLibrary = [[ ALAssetsLibrary alloc ] init ]; void ( ^ AddAsset )( ALAssetsLibrary * , NSURL * ) = ^ ( ALAssetsLibrary * assetsLibrary , NSURL * assetURL ) { [ assetsLibrary assetForURL : assetURL resultBlock :^ ( ALAsset * asset ) { [ assetsLibrary enumerateGroupsWithTypes : ALAssetsGroupAll usingBlock :^ ( ALAssetsGroup * group , BOOL * stop ) { if ([[ group valueForProperty : ALAssetsGroupPropertyName ] isEqualToString : customAlbumName ]) { [ group addAsset : asset ]; if ( completionBlock ) { completionBlock (); } } } failureBlock :^ ( NSError * error ) { if ( failureBlock ) { failureBlock ( error ); } }]; } failureBlock :^ ( NSError * error ) { if ( failureBlock ) { failureBlock ( error ); } }]; }; [ assetsLibrary writeImageDataToSavedPhotosAlbum : imageData metadata : metadata completionBlock :^ ( NSURL * assetURL , NSError * error ) { if ( customAlbumName ) { [ assetsLibrary addAssetsGroupAlbumWithName : customAlbumName resultBlock :^ ( ALAssetsGroup * group ) { if ( group ) { [ assetsLibrary assetForURL : assetURL resultBlock :^ ( ALAsset * asset ) { [ group addAsset : asset ]; if ( completionBlock ) { completionBlock (); } } failureBlock :^ ( NSError * error ) { if ( failureBlock ) { failureBlock ( error ); } }]; } else { AddAsset ( assetsLibrary , assetURL ); } } failureBlock :^ ( NSError * error ) { AddAsset ( assetsLibrary , assetURL ); }]; } else { if ( completionBlock ) { completionBlock (); } } }]; } @end;