StackOverflow 文档 iOS 教程 UIGestureRecognizer UIGestureRecognizer UITapGestureRecognizer UITapGestureRecognizer（双击） 在 Interface Builder 中添加手势识别器 UILongPressGestureRecognizer UISwipeGestureRecognizer UIPinchGestureRecognizer UIRotationGestureRecognizer UIPanGestureRecognizer UITapGestureRecognizer