Question

我有一个iOS应用程序，用户必须在使用该应用程序之前注册。我在Storyboard中创建了UI，我正在从UITextfields中读取用户详细信息。然后，我将详细信息发送到Register API，发送回JSON响应。我正在使用NSURLConnection进行通信。

以下是我从测试网址收到的回复 - 仅用于测试目的：的 {＆＃34;用户名＆＃34;：＆＃34;汉斯＆＃34;＆＃34;密码＆＃34;：＆＃34;汉斯＆＃34;}

然而，当我尝试读取密码以确保用户不存在时（再次，仅用于测试目的），我返回nil以返回密码值。

在我的.h文件中，我声明了数据和连接：

@interface RegisterViewController : UIViewController <NSURLConnectionDataDelegate>
{
    // Conform to the NSURLConnectionDelegate protocol and declare an instance variable to hold the response data
    NSMutableData *buffer;
    NSURLConnection *myNSURLConnection;
}

在我的.m文件中，当有人点击REGISTER按钮时，我创建请求并启动连接，如下所示。我在示例中给出了一个虚拟URL，但我收到的响应是：的 {＆＃34;用户名＆＃34;：＆＃34;汉斯＆＃34;＆＃34;密码＆＃34;：＆＃34;汉斯＆＃34;}

- (IBAction)registerButtonClicked:(id)sender
{
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"http://myDummyURL/Login.php"]];

    // Construct the JSON Data
    NSDictionary *stringDataDictionary = @{@"firstname": firstname, @"lastname": lastname, @"email": email, @"password" : password, @"telephone" : telephone};
    NSError *error;
    NSData *requestBodyData = [NSJSONSerialization dataWithJSONObject:stringDataDictionary options:0 error:&error];

    // Specify that it will be a POST request
    [request setHTTPMethod:@"POST"];

    // Set header fields
    [request setValue:@"text/plain" forHTTPHeaderField:@"Accept"];
    [request setValue:@"application/json; charset=utf-8" forHTTPHeaderField:@"Content-Type"];

    //NSData *requestBodyData = [stringData dataUsingEncoding:NSUTF8StringEncoding];
    [request setHTTPBody:requestBodyData];

    myNSURLConnection = [NSURLConnection connectionWithRequest:request delegate:self];

    // Ensure the connection was created
    if (myNSURLConnection)
    {
        // Initialize the buffer
        buffer = [NSMutableData data];

        // Start the request
        [myNSURLConnection start];
    }
}

此处创建连接没有问题。

在我的.m文件中，我实现了委托方法，在connectionDidFinishLoading（）中，我尝试读取返回的JSON。以下是我正在使用的代码。

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    // Dispatch off the main queue for JSON processing
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

        NSError *error = nil;
        NSString *jsonString = [[NSJSONSerialization JSONObjectWithData:buffer options:0 error:&error] description];

        // Dispatch back to the main queue for UI
        dispatch_async(dispatch_get_main_queue(), ^{

            // Check for a JSON error
            if (!error)
            {
                NSError *error = nil;
                NSArray *jsonArray = [NSJSONSerialization JSONObjectWithData:[jsonString dataUsingEncoding:NSUTF8StringEncoding] options:NSJSONReadingMutableContainers error:&error];
                NSDictionary *dictionary = [jsonArray objectAtIndex:0];
                NSString *test = [dictionary objectForKey:@"password"];
                NSLog(@"Test is: %@", test);
            }
            else
            {
                NSLog(@"JSON Error: %@", [error localizedDescription]);
            }

            // Stop animating the Progress HUD

        });
    });
}

从下面的日志屏幕抓取，您可以看到返回的jsonString具有值，但jsonArray始终为nil。错误读取：错误NSError * domain：@＆＃34; NSCocoaErrorDomain＆＃34; - 代码：3840 0x00007ff158498be0

提前致谢。

Answer 1

您的jsonString实际上是由NSDictionary创建的NSJSONSerialization对象 - 您正在寻找，没有数组。在JSON字符串中，花括号{}表示字典，方括号[]表示数组

试试这个

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
  // Dispatch off the main queue for JSON processing
  dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

    NSError *error = nil;
    NSDictionary *dictionary = [NSJSONSerialization JSONObjectWithData:buffer options:0 error:&error];

    // Dispatch back to the main queue for UI
    dispatch_async(dispatch_get_main_queue(), ^{

        // Check for a JSON error
        if (!error)
        {
            NSString *test = [dictionary objectForKey:@"password"];
            NSLog(@"Test is: %@", test);
        }
        else
        {
            NSLog(@"JSON Error: %@", [error localizedDescription]);
        }

        // Stop animating the Progress HUD

    });
  });
}

修改：我忽略了description行末尾的NSJSONSerialization方法。当然必须删除。

Answer 2

您的代码有两个问题：

您正在将JSON服务器响应转换为NSString。
您的JSON数据确实是NSDictionary。

这必须解决您的问题：

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
  // Dispatch off the main queue for JSON processing
  dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

    NSError *error = nil;
    NSDictionary *dictionary = [NSJSONSerialization JSONObjectWithData:buffer options:0 error:&error];

    // Dispatch back to the main queue for UI
    dispatch_async(dispatch_get_main_queue(), ^{

        // Check for a JSON error
        if (!error)
        {
            NSString *test = [dictionary objectForKey:@"password"];
            NSLog(@"Test is: %@", test);
        }
        else
        {
            NSLog(@"JSON Error: %@", [error localizedDescription]);
        }

        // Stop animating the Progress HUD

    });
  });
}

NSURLConnection上返回的JSON数据

2 个答案: