压缩gif文件的二进制NSData

利用CoreGraphics/CoreGraphics.h API转换GIF图片并再次转成符合要求的图片的二进制文件

UIImage+imgZip

- (UIImage *)compressToByte:(NSUInteger)maxLength { // Compress by quality CGFloat compression = 1; NSData *data = UIImageJPEGRepresentation(self, compression); if (data.length < maxLength) return self; CGFloat max = 1; CGFloat min = 0; for (int i = 0; i < 6; ++i) { compression = (max + min) / 2; data = UIImageJPEGRepresentation(self, compression); if (data.length < maxLength * 0.9) { min = compression; } else if (data.length > maxLength) { max = compression; } else { break; } } UIImage *resultImage = [UIImage imageWithData:data]; if (data.length < maxLength) return resultImage; // Compress by size NSUInteger lastDataLength = 0; while (data.length > maxLength && data.length != lastDataLength) { lastDataLength = data.length; CGSize size = CGSizeMake(200, 200); UIGraphicsBeginImageContext(size); [resultImage drawInRect:CGRectMake(0, 0, size.width, size.height)]; resultImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); data = UIImageJPEGRepresentation(resultImage, compression); } resultImage = [UIImage imageWithData:data]; return resultImage; } - (UIImage *)zipSize{ if (self.size.width < 200) { return self; } CGSize size = CGSizeMake(200, 200); UIGraphicsBeginImageContext(size); [self drawInRect:CGRectMake(0, 0, size.width, size.height)]; UIImage *image = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return image; } - (UIImage *)zip{ UIImage *image = [self compressToByte:2*1024*1024]; return [image zipSize]; }

#pragma mark 压缩GIF动图的时候------------------ -(NSData *)zipGIFWithData:(NSData *)data { if (!data) { return nil; } CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFDataRef)data, NULL); size_t count = CGImageSourceGetCount(source); UIImage *animatedImage = nil; NSMutableArray *images = [NSMutableArray array]; NSTimeInterval duration = 0.0f; for (size_t i = 0; i < count; i++) { CGImageRef image = CGImageSourceCreateImageAtIndex(source, i, NULL); duration += [self frameDurationAtIndex:i source:source]; UIImage *ima = [UIImage imageWithCGImage:image scale:[UIScreen mainScreen].scale orientation:UIImageOrientationUp]; ima = [ima zip]; [images addObject:ima]; CGImageRelease(image); if (!duration) { duration = (1.0f / 10.0f) * count; } animatedImage = [UIImage animatedImageWithImages:images duration:duration]; } CFRelease(source); return UIImagePNGRepresentation(animatedImage); }

- (float)frameDurationAtIndex:(NSUInteger)index source:(CGImageSourceRef)source{ float frameDuration = 0.1f; CFDictionaryRef cfFrameProperties = CGImageSourceCopyPropertiesAtIndex(source, index, nil); NSDictionary *frameProperties = (__bridge NSDictionary *)cfFrameProperties; NSDictionary *gifProperties = frameProperties[(NSString *)kCGImagePropertyGIFDictionary]; NSNumber *delayTimeUnclampedProp = gifProperties[(NSString *)kCGImagePropertyGIFUnclampedDelayTime]; if (delayTimeUnclampedProp) { frameDuration = [delayTimeUnclampedProp floatValue]; } else { NSNumber *delayTimeProp = gifProperties[(NSString *)kCGImagePropertyGIFDelayTime]; if (delayTimeProp) { frameDuration = [delayTimeProp floatValue]; } } if (frameDuration < 0.011f) { frameDuration = 0.100f; } CFRelease(cfFrameProperties); return frameDuration; }