Sdwebimage source code comb 4 ＃ introduce several usages of existing code

Usage examples ：

BJCAImageView As UIImageView An alternative

The most common use is and UITableView Combined use of ：

• - stay Interface Builder Lieutenant general UIImageView As UITableViewCell The child views ;
• - In the identification panel , Set the class name to BJCAWebImageView;
• - from bundle Set a picture as a bitmap ;
• - stay tableview:cellForRowAtIndexPath: In the method , Download the pictures url By calling setImageWithURL The method is passed in ,

Everything will be handled , From parallel download to cache management .

Asynchronous Image Downloader

It can be used independently and inherited from NSOperation Image Downloader for . Just create one BJCAWebImageDownloader example , Use its constructor ：

downloader = [BJCAWebImageDownloader downloaderWithURL:url target:self action:@selector(downloadFinishedWithImage:)];

The download will be queued immediately ,downloadFinishedWithImage: Method will be called after the image download is completed , We need to pay attention to , It may be in a non main thread .

Asynchronous image storage

You can use singular numbers based on NSOperation Image cache storage .BJCAImageCache There is a memory cache and an optional disk cache . Disk cache writes are performed asynchronously , Not to UI Add unnecessary delays .

BJCAImageCache Class for convenience , Created a singleton method , But if you want to have your own cache namespace , You can create instances of this class by yourself .

To find cached images , have access to imageForKey: Method . If you return nil, It means that the cache does not currently own images . therefore , We need to generate and cache it . Cache key key Is the unique identification of the application of the image to be cached . It is usually the absolute of the image URL.

UIImage *cachedImage = [[BJCAImageCache sharedImageCache] imageFromKey:[url absoluteString]];

By default , Image not found in cache , Will continue to look in the disk , It can also be used directly -(UIImage *)imageFromKey:(NSString *)key fromDisk:(BOOL)fromDisk; Method .

Store pictures in cache , have access to -(void)storeImage:(UIImage *)image forKey:(NSString *)key; Method .

By default , Images will be stored in memory and asynchronously on disk . If you only want memory cache, you can use -(void)storeImage:(UIImage *)image foeKey:(NSString *)key toDisk:(BOOL)toDisk; Method , take toDisk The parameter is set to NO.