异步加载图片-SDWebImage

异步加载图片-SDWebImage

SDWebImage缓存原理

1.UIImageView 加载

//导入<UIImageView+WebCache.h>
#import <UIImageView+WebCache.h>

//placeholderImage加载过程中出现的图片
[_homeImageView sd_setImageWithURL:URL(source.imgUrl) placeholderImage:nil];

2.异步加载获取网络图片

建议使用这个方法的时候单独创建一个公用的方法（例如Block）

// 方法1:只下载图片，不管理图片，不会缓存图片到内存和本地
[[SDWebImageDownloader sharedDownloader] downloadImageWithURL:url options:0 progress:^(NSInteger receivedSize, NSInteger expectedSize) {
// 下载进度block
} completed:^(UIImage *image, NSData *data, NSError *error, BOOL finished) {
// 下载完成block
}];

// 方法2:既下载图片，又管理图片。其实方法2内部也是调用的方法1。只不过方法2会缓存图片，并且管理下载队列。
[[SDWebImageManager sharedManager] downloadImageWithURL:url options:0 progress:^(NSInteger receivedSize, NSInteger expectedSize) {
// 下载进度block
} completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, BOOL finished, NSURL *imageURL) {
// 下载完成block
}];

//定义Block块
typedef void(^ImgBlockType)(UIImage *image);

/**
*  @param urlString 网络请求的图片Url
*/
+ (void)imageUrl:(NSString *)urlString success:(ImgBlockType)imgBlock {

[[SDWebImageManager sharedManager] downloadImageWithURL:URL(urlString) options:0 progress:^(NSInteger receivedSize, NSInteger expectedSize) {

} completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, BOOL finished, NSURL *imageURL) {
imgBlock(image);
}];
}

3.加载Gif

//加载本地Gif
NSString  *name = @"smallCow.gif";
NSString  *filePath = [[NSBundle bundleWithPath:[[NSBundle mainBundle] bundlePath]]pathForResource:name ofType:nil];
NSData  *imageData = [NSData dataWithContentsOfFile:filePath];
loadingImageView.backgroundColor = [UIColor clearColor];

//方法1
loadingImageView.image = [UIImage sd_animatedGIFWithData:imageData];

//方法2
[loadingImageView sd_setImageWithURL:[NSURL fileURLWithPath:filePath]];

[self.view addSubview: loadingImageView];

[loadingImageView sd_setImageWithURL:[NSURL URLWithString:@"http://www.XXXX.gif"]];