iphone – Objective-C相当于curl请求

curl -u username:password "http://www.example.com/myapi/getdata"

我实现了以下内容,我得到一个数据获取错误Domain = kCFErrorDomainCFNetwork Code = 303 with NSErrorFailingURLKey = http://www.example.com/myapi/getdata：

// Make a call to the API to pull out the categories
NSURL *url = [NSURL URLWithString:@"http://www.example.com/myapi/getdata"];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];

// Create the username:password string for the request
NSString *loginString = [NSString stringWithFormat:@"%@:%@",API_USERNAME,API_PASSWORD];

// Create the authorisation string from the username password string
NSData *postData = [loginString dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES];
NSString *postLength = [NSString stringWithFormat:@"%d",[postData length]];

[request setURL:url];
[request setHTTPMethod:@"GET"];
[request setValue:postLength forHTTPHeaderField:@"Content-Length"];
[request setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
[request setHTTPBody:postData];

NSError *error;
NSURLResponse *response;
NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];

我希望有人能够找到我操作卷曲请求并指向正确方向的错误.有什么明显的东西我错过了吗？ API返回的数据采用JSON格式.