ios 弹出用户提示框

iOS9

UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"Title" message:[error localizedDescription] preferredStyle:UIAlertControllerStyleAlert];
    UIAlertAction *actionOk = [UIAlertAction actionWithTitle:@"OK"   style:UIAlertActionStyleDefault   handler:nil];
    [alertController addAction:actionOk];
    [self presentViewController:alertController animated:YES completion:nil];