UIImageView支持动图（ｇｉｆ）

思路一　给UIImageView　扩展一个Ｃａｔｅｇｏｒｙ
基于Image I/O　CGImageSourceRef、CGImageDestinationRef

• (void)showGifImageWithData:(NSData *)data {
  ／／获取动画时长
  NSTimeInterval duration = [self durationForGifData:data];
  ／／ｉｍａｇｅ　ｓｏｕｒｃｅｓ　
  CGImageSourceRef source = CGImageSourceCreateWithData(toCF data, NULL);
  ／／动画
  [self animatedGIFImageSource:source andDuration:duration];

CFRelease(source);
}

• (NSTimeInterval)durationForGifData:(NSData *)data {

char graphicControlExtensionStartBytes[] = {0x21,0xF9,0x04};

double duration=0;

NSRange dataSearchLeftRange = NSMakeRange(0, data.length);

while(YES){

NSRange frameDescriptorRange = [data rangeOfData:[NSData dataWithBytes:graphicControlExtensionStartBytes

length:3]

options:NSDataSearchBackwards

range:dataSearchLeftRange];

if(frameDescriptorRange.location!=NSNotFound){

NSData *durationData = [data subdataWithRange:NSMakeRange(frameDescriptorRange.location+4, 2)];

unsigned char buffer[2];

[durationData getBytes:buffer];

double delay = (buffer[0] | buffer[1] << 8);

duration += delay;

dataSearchLeftRange = NSMakeRange(0, frameDescriptorRange.location);

}else{

break;

}

}

return duration/100;

}

• (void)animatedGIFImageSource:(CGImageSourceRef) source

andDuration:(NSTimeInterval) duration {

if (!source) return;

size_t count = CGImageSourceGetCount(source);

NSMutableArray *images = [NSMutableArray arrayWithCapacity:count];

for (size_t i = 0; i < count; ++i) {

CGImageRef cgImage = CGImageSourceCreateImageAtIndex(source, i, NULL);

if (!cgImage)

return;

[images addObject:[UIImage imageWithCGImage:cgImage]];

CGImageRelease(cgImage);

}

[self setAnimationImages:images];

[self setAnimationDuration:duration];

[self startAnimating];
}

思路二：已知ｗｅｂｖｉｅｗ　是可以加载ｇｉｆ图的
注意：关闭ｗｅｂｖｉｅｗ的交互。。。