- (void)viewDidLoad {
    // 單擊的 Recognizer
    UITapGestureRecognizer* singleRecognizer;
    singleRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleSingleTapFrom)];
    singleTapRecognizer.numberOfTapsRequired = 1; // 單擊
    [self.view addGestureRecognizer:singleRecognizer];
    
    // 雙擊的 Recognizer
    UITapGestureRecognizer* double;
    doubleRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleDoubleTapFrom)];
    doubleTapRecognizer.numberOfTapsRequired = 2; // 雙擊
    [self.view addGestureRecognizer:doubleRecognizer];
    
    // 關鍵在這一行，如果雙擊確定偵測失敗才會觸發單擊
    [singleRecognizer requireGestureRecognizerToFail:doubleRecognizer];
    [singleRecognizer release];
    [doubleRecognizer release];
}