iOS GIF图尺寸过大，无法显示

        NSArray *resources = [PHAssetResource assetResourcesForAsset:cell.model.asset];
        NSURL * pathURL = [(PHAssetResource *)resources.firstObject valueForKey:@"privateFileURL"];
        NSData * data = [NSData dataWithContentsOfURL:pathURL];
        if([pathURL.absoluteString hasSuffix:@".GIF"] ||  data.length>20*1024*1024){//阿里云要求小于20M
            //将GIF图片转换成对应的图片源
            CGImageSourceRef gifSource = CGImageSourceCreateWithData((__bridge CFDataRef)data, NULL);
            //获取其中图片源个数，即由多少帧图片组成
            size_t frameCout = CGImageSourceGetCount(gifSource);
            CFRelease(gifSource);
            if(frameCout > 150){
                [tzImagePickerVc showAlertWithTitle:@"该GIF图尺寸过大，无法发送"];
                return;
            }
        }