如何使用NSURLRequest在Http请求中发送json数据

Question

我是Objective-c的新手，从最近开始，我就在请求/响应中投入了大量精力。我有一个工作示例，可以调用url（通过http
GET）并解析返回的json。

下面的工作示例

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    [responseData setLength:0];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
    [responseData appendData:data];
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
  NSLog([NSString stringWithFormat:@"Connection failed: %@", [error description]]);
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
    [connection release];
  //do something with the json that comes back ... (the fun part)
}

- (void)viewDidLoad
{
  [self searchForStuff:@"iPhone"];
}

-(void)searchForStuff:(NSString *)text
{
  responseData = [[NSMutableData data] retain];
    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.whatever.com/json"]];
    [[NSURLConnection alloc] initWithRequest:request delegate:self];
}

我的第一个问题是-这种方法会扩大规模吗？还是这不是异步的（意味着我在应用程序等待响应时阻止了UI线程）

我的第二个问题是-如何修改请求的一部分以执行POST而不是GET？是否只是像这样修改HttpMethod？

[request setHTTPMethod:@"POST"];

最后-如何将一组json数据作为简单字符串添加到此帖子中（例如）

{
    "magic":{
               "real":true
            },
    "options":{
               "happy":true,
                "joy":true,
                "joy2":true
              },
    "key":"123"
}

先感谢您

Answer 1

这是我的工作（请注意，发送到我的服务器的JSON必须是一个字典，其中包含key = question..ie {：question =>
{dictionary}}}的一个值（另一个字典））：

NSArray *objects = [NSArray arrayWithObjects:[[NSUserDefaults standardUserDefaults]valueForKey:@"StoreNickName"],
  [[UIDevice currentDevice] uniqueIdentifier], [dict objectForKey:@"user_question"],     nil];
NSArray *keys = [NSArray arrayWithObjects:@"nick_name", @"UDID", @"user_question", nil];
NSDictionary *questionDict = [NSDictionary dictionaryWithObjects:objects forKeys:keys];

NSDictionary *jsonDict = [NSDictionary dictionaryWithObject:questionDict forKey:@"question"];

NSString *jsonRequest = [jsonDict JSONRepresentation];

NSLog(@"jsonRequest is %@", jsonRequest);

NSURL *url = [NSURL URLWithString:@"https://xxxxxxx.com/questions"];

NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url
             cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60.0];


NSData *requestData = [jsonRequest dataUsingEncoding:NSUTF8StringEncoding];

[request setHTTPMethod:@"POST"];
[request setValue:@"application/json" forHTTPHeaderField:@"Accept"];
[request setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
[request setValue:[NSString stringWithFormat:@"%d", [requestData length]] forHTTPHeaderField:@"Content-Length"];
[request setHTTPBody: requestData];

NSURLConnection *connection = [[NSURLConnection alloc]initWithRequest:request delegate:self];
if (connection) {
 receivedData = [[NSMutableData data] retain];
}

然后，receivedData由以下方式处理：

NSString *jsonString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSDictionary *jsonDict = [jsonString JSONValue];
NSDictionary *question = [jsonDict objectForKey:@"question"];

这不是100％清楚的，需要重新阅读，但是所有内容都应该在这里，以帮助您入门。据我所知，这是异步的。进行这些调用时，我的UI未被锁定。希望有帮助。