ios - NSURLConnection 之前应该调用 connectionDidFinishLoading 吗？

我正在开发一个触发几个 NSURL 请求的 iOS 应用程序。我创建了一个实现 didReceiveData 的 WebService 类，如下所示:

- (void)connectionNSURLConnection *)connection didReceiveDataNSData *)data {
    // Append the new data to the instance variable you declared
    [_responseData appendData:data];
}

其中 _responseData 是 NSMutableData* 属性。然后我创建了几个子类来创建它们的特定请求并实现 connectionDidFinishLoading。具体来说，我有一个 RegisterService 类，它像这样实现它:

- (void)connectionDidFinishLoadingNSURLConnection *)connection {
    // The request is complete and data has been received
    // You can parse the stuff in your instance variable now
    NSError *error = nil;
    _parsedData = [NSJSONSerialization JSONObjectWithData:_responseData options:kNilOptions error:&error];
    NSLog(@"register data: %@",_parsedData);
    registerAnswer serverAnswer = [[_parsedData objectForKey"success"] integerValue];

    if (serverAnswer == REGISTER_SUCCESS) {
        // Give data to delegate to handle
        [self.delegate successRegister];
    }
    else { // serverAnswer == REGISTER_FAIL
        NSLog(@"register message: %@",[[_parsedData objectForKey"message"] stringValue]);
        [self.delegate failedRegister];
    }
}

我有 2 个使用此服务的不同 View Controller 。其中一个是这样调用它的:

self.personRegistering.username = self.txtUsername.text;
self.personRegistering.password = self.txtPassword.text;
if (self.personRegistering.isCustomer) {
    // register customer
    DGRegisterService* myRegisterService = [[DGRegisterService alloc] initWithDelegate:self];
    [myRegisterService registerPerson:self.personRegistering];
}
else {
    // continue to get picture
    [self performSegueWithIdentifier"RegisterPageThreeToFour" sender:self];
}

而且效果很好。另一个(第四页)让用户在注册之前拍照。代码如下:

- (IBAction)btnTakePictureid)sender {
    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
        // Camera is available
        UIImagePickerController* myCamera = [[UIImagePickerController alloc] init];
        myCamera.sourceType = UIImagePickerControllerSourceTypeCamera;
        myCamera.delegate = self;
        [self presentViewController:myCamera animated:YES completion:NULL];
    }
}

#pragma mark - UIImagePicker Delegate

- (void) imagePickerControllerUIImagePickerController *)picker didFinishPickingMediaWithInfoNSDictionary *)info {
    [picker dismissViewControllerAnimated:YES completion:NULL];
    // Register person first
    DGRegisterService* myRegisterService = [[DGRegisterService alloc] initWithDelegate:self];
    [myRegisterService registerPerson:self.personRegistering];

//    // Now send pic
//    UIImage* picture = [info objectForKey:UIImagePickerControllerOriginalImage];
//    DGUploadService* myUploadService = [[DGUploadService alloc]     initWithDelegate:self];
//    [myUploadService uploadImage:picture forUsername:self.personRegistering.username];
}

现在，第二个发送请求并且服务器正确处理它，发回这个 JSON 对象:

{"success":1,"message":"Account successfully created."}

这是我所期望的。但是，两个 NSLog 语句都显示“(null)”。有时，应用程序崩溃是因为 objectForKey 被发送到不响应它的实例。有时，在我在 XCode 上点击“停止”后，控制台会显示 JSON 对象。其余时间它不会崩溃或显示对象。

由于此页面使用相机，我只能在 iPhone 上进行测试，而不是模拟器。另一个页面在模拟器和 iPhone 中每次都正确显示 JSON 对象。我使用的 iPhone 是 iOS7.1.1 的 4S。

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Best Answer-推荐答案

如果你的意思是NSLog在下面几行:

NSError *error = nil;
_parsedData = [NSJSONSerialization JSONObjectWithData:_responseData options:kNilOptions error:&error];
NSLog(@"register data: %@",_parsedData);

有时会打印“(null)”，这可能是由 JSONObjectWithData 调用中的错误引起的。

我建议添加

NSLog(@"received data: %@", _responseData);

检查数据是否一切正常，并且

NSLog(@"register data: %@ -- (error: %@)",_parsedData, [error localizedDescription]);

查看是否返回错误。

关于ios - NSURLConnection 之前应该调用 connectionDidFinishLoading 吗？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/24460482/