利用afn进行网络下载 文件 货不多说 上代码

import "ViewController.h"

import "AFNetworking.h"

{
    // 下载操作
    NSURLSessionDownloadTask *_downloadTask;
}
@end

@implementation ViewController

• (void)downFileFromServer{

  NSURL *URL = [NSURL URLWithString:@"http://www.baidu.com/img/bdlogo.png"];

  NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];

  //AFN3.0+基于封住URLSession的句柄
  AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:configuration];

  //请求
  NSURLRequest *request = [NSURLRequest requestWithURL:URL];

  //下载Task操作
  _downloadTask = [manager downloadTaskWithRequest:request progress:^(NSProgress * _Nonnull downloadProgress) {

    // @property int64_t totalUnitCount;  需要下载文件的总大小
    // @property int64_t completedUnitCount; 当前已经下载的大小
    
    // 给Progress添加监听 KVO
    NSLog(@"%f",1.0 * downloadProgress.completedUnitCount / downloadProgress.totalUnitCount);
    // 回到主队列刷新UI
    dispatch_async(dispatch_get_main_queue(), ^{
        self.progressView.progress = 1.0 * downloadProgress.completedUnitCount / downloadProgress.totalUnitCount;
    });
  

  } destination:^NSURL * _Nonnull(NSURL * _Nonnull targetPath, NSURLResponse * _Nonnull response) {

    //- block的返回值, 要求返回一个URL, 返回的这个URL就是文件的位置的路径
  
    NSString *cachesPath = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
    NSString *path = [cachesPath stringByAppendingPathComponent:response.suggestedFilename];
    return [NSURL fileURLWithPath:path];
  

  } completionHandler:^(NSURLResponse * _Nonnull response, NSURL * _Nullable filePath, NSError * _Nullable error) {
  // filePath就是你下载文件的位置，你可以解压，也可以直接拿来使用

    NSString *imgFilePath = [filePath path];// 将NSURL转成NSString
    UIImage *img = [UIImage imageWithContentsOfFile:imgFilePath];
    self.imageView.image = img;
  

  }];
  }

• (void)viewDidLoad {
  [super viewDidLoad];

  //网络监控句柄
  AFNetworkReachabilityManager *manager = [AFNetworkReachabilityManager sharedManager];

  //要监控网络连接状态，必须要先调用单例的startMonitoring方法
  [manager startMonitoring];

  [manager setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status) {
  //status:
  //AFNetworkReachabilityStatusUnknown = -1, 未知
  //AFNetworkReachabilityStatusNotReachable = 0, 未连接
  //AFNetworkReachabilityStatusReachableViaWWAN = 1, 3G
  //AFNetworkReachabilityStatusReachableViaWiFi = 2, 无线连接
  NSLog(@"%d", status);
  }];

  //准备从远程下载文件. -> 请点击下面开始按钮启动下载任务
  [self downFileFromServer];

}

• (IBAction)stopDownloadBtnClick:(id)sender {
  //暂停下载
  [_downloadTask suspend];
  }
• (IBAction)startDownloadBtnClick:(id)sender {
  //开始下载
  [_downloadTask resume];
  }