ios - 从 nsurlconnection 委托(delegate)方法返回响应数据

Question

您好，我正在使用网络服务进行注册，我创建了一个单独的类来访问网络服务并在 View 类上返回响应。

这是我的代码 在按钮上

-(IBAction)placeOrder:(id)sender
 {               
 url = [[NSURL alloc]initWithString:@"http://54.25fdg.239.126/tfl/index.php/service/register"];
 NSString *str = [NSString stringWithFormat:@"name=%@&phoneNumber=%@&emailAddress=%@&password=%@&addressLine1=%@&addressLine2=%@&city=%@&pincode=%@&landmark=%@&specialInstruction=%@",txtUserName.text,txtPhone.text,txtEmail.text,txtPassword.text,addressLine1Tf.text,addressLine2Tf.text,cityTf.text,pinCodeTf.text,landMarkTf.text,specialInstrTv.text];
 WebServices *webservice = [[WebServices alloc]init];
 [webservice getDataFromService:url data:str];
 responseDictionary = [webservice returnResponseData];
 }

在调用 getDataFromService 方法后，它会调用 returnRespnoseData 方法。然后它调用从 getDataFromService 调用的连接方法。所以我从 returnResponseData 得到了 nil 响应。任何人都可以告诉我如何管理它或如何将 didfinishloading 方法的响应返回到主视图类？在 webservice.m

-(void)getDataFromService:(NSURL *)url data:(NSString *)parameterString
 {
  NSData *postData = [parameterString dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
  NSString *postLength = [NSString stringWithFormat:@"%lu",(unsigned long)[postData length]];
  NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
  [request setURL:url];
  [request setHTTPMethod:@"POST"];
  [request setValue:postLength forHTTPHeaderField:@"Content-Length"];
  [request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
  [request setHTTPBody:postData];
  NSURLConnection *conn = [[NSURLConnection alloc]initWithRequest:request delegate:self];
  [conn start];
 }

在连接的最后一个方法中，我在字典中得到了作为 jsonDec 的响应。

 -(void)connectionDidFinishLoading:(NSURLConnection *)connection
{
NSError* error ;
 _jsonDec = [NSJSONSerialization JSONObjectWithData:_responseData options:NSJSONReadingAllowFragments error:&error];
}

将 jsonDec 返回给 View 类

-(NSDictionary *)returnResponseData
{
 return _jsonDec;
}

Answer 1

为确保应用程序在响应到达后将 jsondata 返回给 viewclass，请在您的类的 .h 文件中定义一个 block :

typedef void(^getDataBlock)(id jsonObject);

那么您的 getDataFromService 方法可能如下所示:

-(void)getDataFromService:(NSURL *)url data:(NSString *)parameterString getDataBlock:(getDataBlock)returnBlock{
NSLog(@"Getting Data");
NSData *postData = [parameterString dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
NSString *postLength = [NSString stringWithFormat:@"%lu",(unsigned long)[postData length]];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
[request setURL:url];
[request setHTTPMethod:@"POST"];
[request setValue:postLength forHTTPHeaderField:@"Content-Length"];
[request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
[request setHTTPBody:postData];
[NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
    NSError *error = [[NSError alloc] init];
    id jsonDec = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingAllowFragments error:&error];
    returnBlock(jsonDec);
}];
}

在您的 View 类中，您现在可以这样做:

-(void)test{
//Insert the right name for your class where you do the request and insert the right values
[backendClass getDataFromService:[NSURL URLWithString:@"www.google.de"] data:@"blablabla" getDataBlock:^(id jsonObject) {
   //Make sure you're on the mainthread for UI-updates
    dispatch_async(dispatch_get_main_queue(), ^{
        self.titleLabel.text = [jsonObject objectForKey:@"title"];
    });
}];
}