根据网络状态加载图片

外部引用

/** 小图 */
@property (nonatomic, copy) NSString *image0;
/** 中图 */
@property (nonatomic, copy) NSString *image2;
/** 大图 */
@property (nonatomic, copy) NSString *image1;


    [self.imageView SH_setOriginImage:topic.image1 thumbnailImage:topic.image0 placeholder:nil];

代码

#import 

@interface UIImageView (Download)
- (void)SH_setOriginImage:(NSString *)originImageURL thumbnailImage:(NSString *)thumbnailImageURL placeholder:(UIImage *)placeholder;
@end

#import "UIImageView+Download.h"
#import 
#import 

@implementation UIImageView (Download)
- (void)SH_setOriginImage:(NSString *)originImageURL thumbnailImage:(NSString *)thumbnailImageURL placeholder:(UIImage *)placeholder
{
//    [[SDWebImageManager sharedManager]setCacheKeyFilter:^(NSURL *url) {
//        // 所有缓存图片的key后面都有个-SH后缀
//        return [NSString stringWithFormat:@"%@-SH", url.absoluteString];
//    }];
    
    // 根据网络状态来加载图片
    AFNetworkReachabilityManager *mgr = [AFNetworkReachabilityManager sharedManager];
    // 获得原图（SDWebImage的图片缓存是用图片的url字符串作为key）
    UIImage *originImage = [[SDImageCache sharedImageCache] imageFromDiskCacheForKey:originImageURL];
    if (originImage) { // 原图已经被下载过
        self.image = originImage;
    } else { // 原图并未下载过
        if (mgr.isReachableViaWiFi) {
            [self sd_setImageWithURL:[NSURL URLWithString:originImageURL] placeholderImage:placeholder];
        } else if (mgr.isReachableViaWWAN) {
#warning downloadOriginImageWhen3GOr4G配置项的值需要从沙盒里面获取
            // 3G\4G网络下时候要下载原图
            BOOL downloadOriginImageWhen3GOr4G = YES;
            if (downloadOriginImageWhen3GOr4G) {
                [self sd_setImageWithURL:[NSURL URLWithString:originImageURL] placeholderImage:placeholder];
            } else {
                [self sd_setImageWithURL:[NSURL URLWithString:thumbnailImageURL] placeholderImage:placeholder];
            }
        } else { // 没有可用网络
            UIImage *thumbnailImage = [[SDImageCache sharedImageCache] imageFromDiskCacheForKey:thumbnailImageURL];
            if (thumbnailImage) { // 缩略图已经被下载过
                self.image = thumbnailImage;
            } else { // 没有下载过任何图片
                // 占位图片;
                self.image = placeholder;
            }
        }
    }
}

}
@end