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  1. 1. 1.封装网络(使用SDWebImage和AFNetworking框架)下载图片

1.封装网络(使用SDWebImage和AFNetworking框架)下载图片

程序启动的时候就会调用,需要先在这个方法中开始监测网络

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- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
	// 监控网络状况
    [[AFNetworkReachabilityManager sharedManager] startMonitoring];
}
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#import <UIKit/UIKit.h>
#import <UIImageView+WebCache.h>
@interface UIImageView (Download)
- (void)xy_setOriginImage:(NSString *)originImageURL thumbnailImage:(NSString *)thumbnailImageURL placeholder:(UIImage *)placeholder completed:(SDWebImageCompletionBlock)completedBlock;
- (void)xy_setHeader:(NSString *)headerUrl;
@end
#import "UIImageView+Download.h"
#import <AFNetworkReachabilityManager.h>
#import <UIImageView+WebCache.h>
@implementation UIImageView (Download)
- (void)xy_setOriginImage:(NSString *)originImageURL thumbnailImage:(NSString *)thumbnailImageURL placeholder:(UIImage *)placeholder completed:(SDWebImageCompletionBlock)completedBlock
{
    // 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 sd_setImageWithURL:[NSURL URLWithString:originImageURL] placeholderImage:placeholder completed:completedBlock];
    } else { // 原图并未下载过
        if (mgr.isReachableViaWiFi) {
            [self sd_setImageWithURL:[NSURL URLWithString:originImageURL] placeholderImage:placeholder completed:completedBlock];
        } else if (mgr.isReachableViaWWAN) {
            // 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 completed:completedBlock];
            } else {
                [self sd_setImageWithURL:[NSURL URLWithString:thumbnailImageURL] placeholderImage:placeholder completed:completedBlock];
            }
        } 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 sd_setImageWithURL:[NSURL URLWithString:thumbnailImageURL] placeholderImage:placeholder completed:completedBlock];
            } else { // 没有下载过任何图片
                // 占位图片;
                [self sd_setImageWithURL:nil placeholderImage:placeholder completed:completedBlock];
            }
        }
    }
}
- (void)xy_setHeader:(NSString *)headerUrl
{
    UIImage *placeholder = [UIImage xy_circleImageNamed:@"defaultUserIcon"];
    [self sd_setImageWithURL:[NSURL URLWithString:headerUrl] placeholderImage:placeholder options:0 completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, NSURL *imageURL) {
        // 图片下载失败，直接返回，按照它的默认做法
        if (!image) return;
        
        self.image = [image xy_circleImage];
    }];
}
@end
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  1. 1. 1.封装网络(使用SDWebImage和AFNetworking框架)下载图片