oc调用rest api

   1: - (IBAction)callapi:(id)sender {

   2:     NSURL *url=[NSURL URLWithString:@"http://..."];

   3:     NSURLRequest *request=[NSURLRequest requestWithURL:url];

   4:     [NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {

   5:         //json

   6:         NSDictionary *r=[NSJSONSerialization JSONObjectWithData:data options:0 error:NULL];

   7:         int cnt=[r count];

   8:         NSLog(@"%d",cnt);

   9:         [self resultlbl].text=[NSString stringWithFormat:@"%d",cnt];

  10:  

  11:         //string

  12:         //NSString *str=[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

  13:         //NSLog(str);

  14:         //[self resultlbl].text=r[0][0];

  15:     }];

  16: }