ios - 如何在标签中显示 GET 请求

Question

我的 get 请求仅在命令行 NSLog 中有效。我需要在标签中显示数据，但它不起作用。

-(void)getRequest{

  NSURLSessionConfiguration *getConfigObject = [NSURLSessionConfiguration defaultSessionConfiguration];
  NSURLSession *getSession = [NSURLSession sessionWithConfiguration: getConfigObject delegate: self delegateQueue: [NSOperationQueue mainQueue]];
  NSURL * getUrl = [NSURL URLWithString:@"http://localhost:3000/get"];
  NSURLSessionDataTask * getDataTask = [getSession dataTaskWithURL:getUrl completionHandler:^(NSData *getData, NSURLResponse *getResponse, NSError *getError) {
    if(getError == nil){
       NSString * getString = [[NSString alloc] initWithData: getData encoding: NSUTF8StringEncoding];
       [self.label setText:getString];// doesn't work!
       NSLog(@"Data = %@",getString);}//  it works!!
       MainViewController*l=[[MainViewController alloc]init];

       [l getRequest];
    }
 ];

 [getDataTask resume];
}

Answer 1

dataTaskWithURL 未在主线程上运行，这是更新您的 UI 所必需的。

if (getError == nil) {
    NSString * getString = [[NSString alloc] initWithData: getData encoding: NSUTF8StringEncoding];

    dispatch_async(dispatch_get_main_queue(), ^{
        [self.label setText: getString];
        NSLog(@"Data = %@", getString);

    });

    }

此代码适合您。

您还可以使用:

[[NSOperationQueue mainQueue] addOperationWithBlock:^{
    [self.label setText:getString];       
}];

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