利用afn進行網絡下載 文件 貨不多說 上代碼

import "ViewController.h"

import "AFNetworking.h"

{
    // 下載操作
    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];

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

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

    // @property int64_t totalUnitCount;  需要下載文件的總大小
    // @property int64_t completedUnitCount; 當前已經下載的大小
    
    // 給Progress添加監聽 KVO
    NSLog(@"%f",1.0 * downloadProgress.completedUnitCount / downloadProgress.totalUnitCount);
    // 回到主隊列刷新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, 要求返回一個URL, 返回的這個URL就是文件的位置的路徑
  
    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就是你下載文件的位置，你可以解壓，也可以直接拿來使用

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

  }];
  }

• (void)viewDidLoad {
  [super viewDidLoad];

  //網絡監控句柄
  AFNetworkReachabilityManager *manager = [AFNetworkReachabilityManager sharedManager];

  //要監控網絡連接狀態，必須要先調用單例的startMonitoring方法
  [manager startMonitoring];

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

  //準備從遠程下載文件. -> 請點擊下面開始按鈕啟動下載任務
  [self downFileFromServer];

}

• (IBAction)stopDownloadBtnClick:(id)sender {
  //暫停下載
  [_downloadTask suspend];
  }
• (IBAction)startDownloadBtnClick:(id)sender {
  //開始下載
  [_downloadTask resume];
  }