iOS webapiからのデータ取得

iOS - Web APIの叩き方いろいろ - Qiita
iOS7から追加されたNSURLSessionを使うパターン。や、NSURLConnectionをつかうパターンとか。

- (void)viewDidLoad
{
  [super viewDidLoad];

  NSURLSessionConfiguration *urlSessionConfiguration;
  urlSessionConfiguration = [NSURLSessionConfiguration defaultSessionConfiguration];
  NSURLSession *urlSession = [NSURLSession sessionWithConfiguration:urlSessionConfiguration];
  NSURL *url = [NSURL URLWithString:kEventUrl];

  [UIApplication sharedApplication].networkActivityIndicatorVisible = YES;

  NSURLSessionDataTask *urlSessionDataTask;
  urlSessionDataTask = [urlSession dataTaskWithURL:url
                                 completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
                                   _events = [NSJSONSerialization JSONObjectWithData:data
                                                                             options:NSJSONReadingAllowFragments
                                                                               error:nil];
                                   dispatch_async(dispatch_get_main_queue(), ^{
                                     [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
                                     [self.tableView reloadData];
                                   });
                                 }];
  [urlSessionDataTask resume];
}

inter-arteq :: interaction between art and technology » Blog Archive » iOSでWebAPIからJSONを取得
これもNSURLConnectionを使うパターン。