AFNetworking 如何POST一个JSON数据到服务器

NSString *pathStr=@"http://www.baidu.com" ;

AFHTTPClient *httpClient = [[AFHTTPClient
alloc] initWithBaseURL:[NSURL
URLWithString:@""]];//这里要将url设置为空

httpClient.parameterEncoding =
AFJSONParameterEncoding;

[httpClient setDefaultHeader:@"Accept"
value:@"text/json"];

NSMutableDictionary *params=[[NSMutableDictionary
alloc] init]; // 要传递的json数据是一个字典

[params setObject:UserID
forKey:@"userId"];

[params setObject:[self.contDic
objectForKey:@"weiboId" ]
forKey:@"operateId"];

[params setObject:@"8d0ce196d0eafa27780cc3a7217de71d92474021dc0a4fc593d4f9b9eda320ca"
forKey:@"key"];

// httpClient 的postPath就是上文中的pathStr，即你要访问的URL地址，这里是向服务器提交一个数据请求，

[httpClient postPath:pathStr
parameters:params
success:^(AFHTTPRequestOperation *operation,
id responseObject) {

NSLog(@"data====%@",params);

NSString *responseStr = [[NSString
alloc] initWithData:responseObject
encoding:NSUTF8StringEncoding];

NSLog(@"Request Successful, response '%@'", responseStr);

[responseStr release];

} failure:^(AFHTTPRequestOperation *operation,
NSError *error) {

NSLog(@"[HTTPClient Error]: %@", error);

}];