首先新增手勢方法

  // 長按手勢
- (void)addLongGes
{
    UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(actionLongPress:)];
    // 最短長按時間
    longPress.minimumPressDuration = 1;
    [_imageLeftIV addGestureRecognizer:longPress];
}

  // 長按手勢 （常用）
- (void)actionLongPress:(UILongPressGestureRecognizer *)longPress
{
// 根據手勢的狀態判斷，只有第一次執行時是UIGestureRecognizerStateBegan，其餘都是UIGestureRecognizerStateEnd狀態。
    if (longPress.state == UIGestureRecognizerStateBegan) { 
    // 長按 換張圖片
    // 獲取到長按的view
    UIImageView *imageView = (UIImageView *)longPress.view;
    imageView.image = [UIImage imageNamed:@"Selected"];
    }
}