对UIImageView+WebCache的封装

UIImageView+SDWebImage.h

#import <UIKit/UIKit.h>

typedef void(^DownloadImageSuccessBlock)(UIImage *image);
typedef void(^DownloadImageFailedBlock)(NSError *error);
typedef void(^DownloadImageProgressBlock)(CGFloat progress);

@interface UIImageView (SDWebImage)

/**
 异步加载图片

 @param url 图片地址
 @param imageName 占位图片名
 */
- (void)downloadImage:(NSString *)url placeholder:(NSString *)imageName;

/**
 异步加载图片，可以监听下载进度，成功或失败

 @param url 图片地址
 @param imageName 占位图片名
 @param success 下载成功
 @param failed 下载失败
 @param progress 下载进度
 */
- (void)downloadImage:(NSString *)url
          placeholder:(NSString *)imageName
              success:(DownloadImageSuccessBlock)success
               failed:(DownloadImageFailedBlock)failed
             progress:(DownloadImageProgressBlock)progress;

@end

UIImageView+SDWebImage.m

#import "UIImageView+SDWebImage.h"

#import "UIImageView+WebCache.h"

@implementation UIImageView (SDWebImage)

- (void)downloadImage:(NSString *)url placeholder:(NSString *)imageName {
    
    [self sd_setImageWithURL:[NSURL URLWithString:url] placeholderImage:[UIImage imageNamed:imageName] options:SDWebImageRetryFailed | SDWebImageLowPriority];
}

- (void)downloadImage:(NSString *)url placeholder:(NSString *)imageName success:(DownloadImageSuccessBlock)success failed:(DownloadImageFailedBlock)failed progress:(DownloadImageProgressBlock)progress {
    
    [self sd_setImageWithURL:[NSURL URLWithString:url] placeholderImage:[UIImage imageNamed:imageName] options:SDWebImageRetryFailed | SDWebImageLowPriority progress:^(NSInteger receivedSize, NSInteger expectedSize, NSURL * _Nullable targetURL) {
        
        progress(receivedSize * 1.0 / expectedSize);
        
    } completed:^(UIImage * _Nullable image, NSError * _Nullable error, SDImageCacheType cacheType, NSURL * _Nullable imageURL) {
        
        if (error) {
            
            failed(error);
        } else {
            
            self.image = image;
            success(image);
        }
    }];
    
}

@end