GDRSImageCache 介绍
GDRSImageCache 是 iOS 一个非常小型的图片缓存和更改图片大小的开发包。给定一个 URL 后该库会通过后台线程获取图片并在内存中缓存。
使用方法：
UIImageView *anImageView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 40, 40)];
// create the cache
GDRSImageCache *cache = [[GDRSImageCache alloc] initWithCachedImageFilter:^UIImage *(UIImage *sourceImage) {
// resize the image to the image view size and round the image corners;
// this is called by the cache on a background thread
return [sourceImage gdrs_resizedImageToAspectFitSize:anImageView.bounds.size cornerRadius:10];
}];
// set the default image, which will be returned from
// fetchImageWithURL:completionHandler: if an image coresponding to the
// requested url is not cached yet.
cache.defaultImage = [UIImage imageNamed:<#place holder image name#>];
NSURL *imageUrl = <#an url to a image#>;
// fetch an image; the call returns imidiatly and the callback handler
// is called when the image is fetched over the network
anImageView.image = [cache fetchImageWithURL:imageUrl completionHandler:^(UIImage *image, NSError *error) {
anImageView.image = image;
}];