长按后如何跟踪按钮选择？

Question

我试图模仿键盘的长按提示 UIButton 控件的字母。我要做的是长按 UIButton，在按住按钮后显示 3 个新按钮并选择这 3 个新按钮之一。就像键盘字母建议一样。

我该怎么做？任何的想法？ 谢谢

Answer 1

你有UIControl 只是为了那个UILongPressGestureRecognizer 并且可以通过minimumPressDuration属性设置发稿时间

如果您希望UIButton 上的这种行为，您必须将此手势识别器添加到按钮并处理第一次调用（单击）。

Answer 2

您在 UIControl 上有一套完整的事件（UIButton 是它的子类）来处理您需要的所有触摸事件：

enum {
   UIControlEventTouchDown           = 1 <<  0,
   UIControlEventTouchDownRepeat     = 1 <<  1,
   UIControlEventTouchDragInside     = 1 <<  2,
   UIControlEventTouchDragOutside    = 1 <<  3,
   UIControlEventTouchDragEnter      = 1 <<  4,
   UIControlEventTouchDragExit       = 1 <<  5,
   UIControlEventTouchUpInside       = 1 <<  6,
   UIControlEventTouchUpOutside      = 1 <<  7,
   UIControlEventTouchCancel         = 1 <<  8,

   UIControlEventValueChanged        = 1 << 12,

   UIControlEventEditingDidBegin     = 1 << 16,
   UIControlEventEditingChanged      = 1 << 17,
   UIControlEventEditingDidEnd       = 1 << 18,
   UIControlEventEditingDidEndOnExit = 1 << 19,

   UIControlEventAllTouchEvents      = 0x00000FFF,
   UIControlEventAllEditingEvents    = 0x000F0000,
   UIControlEventApplicationReserved = 0x0F000000,
   UIControlEventSystemReserved      = 0xF0000000,
   UIControlEventAllEvents           = 0xFFFFFFFF
};

• UIControlEventTouchDown 将在您触摸按钮时触发
• 如果您继续按住按钮，UIControlEventTouchDownRepeat 将触发（请注意，此事件将触发多次，因此您应该只处理第一个） - 在这里您应该显示弹出框
• UIControlEventTouchDragExit 将在您将手指从按钮中拖出时触发 - 您应该在此处隐藏弹出框
• UIControlEventTouchDragEnter 将在您将手指拖入按钮时触发 - 在这里您应该显示弹出框
• 当您从按钮上抬起手指时，UIControlEventTouchUpInside、UIControlEventTouchUpOutside 和 UIControlEventTouchCancel 将触发 - 您应该在此处隐藏弹出框
• 等

更新
不过，您将需要实现一些逻辑来处理在弹出框内拖动手指（因为您将从按钮中拖出）。

Answer 3

这已经很老了，但是因为我遇到了同样的问题，所以我会提出我的解决方案。

我的键盘由类 Keyboard 布局和创建，派生自 UIView 每个字母按钮都是从 UIButton 派生的 LetterButton 类。 键盘实现了一个协议，该协议处理来自按钮的 KeyPressed 事件。

对于主键盘的每个按钮，都会应用一个 UILongPressGestureRecognizer：

let longTouchRecognizer = UILongPressGestureRecognizer(target: self, action: #selector(onButtonLongPressed))
longTouchRecognizer.cancelsTouchesInView = false
button.addGestureRecognizer(longTouchRecognizer)
button.delegate = self

与

@objc func onButtonLongPressed (_ sender: UIGestureRecognizer)
{
    if (sender.state == .began)
    {
        guard let tag = sender.view?.tag else { return }
        createPopupView(button: buttons[tag])
    }
}

必须将 cancelsTouchesInView 设置为 false，否则我们将不会收到任何进一步的事件！

在一个按钮上长按时，会创建一个弹出视图，在所触摸的按钮上方有一个或多个按钮。我们可以直接从触摸的按钮滑动到这些按钮。

LetterButton类的实现：

class LetterButton : UIButton
{
  var delegate : LetterButtonDelegate?
  var isInside = false

这是从键盘类调用的：

  func setIsInside(val: Bool)
  {
    if (val)
    {
        if (!isInside)
        {
            setBackgroundColor(UIColor.lightGray, for: .normal)
        }
    }
    else
    {
        if (!isInside)
        {
            setBackgroundColor(UIColor.white, for: .normal)
       }
    }
    isInside = val
}

其实我这里只需要Keyboard类的按钮

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?)
{
    if let touch = touches.first
    {
        let point = touch.location(in: self)
        delegate?.onBegan(button: self, point: point)
    }

    super.touchesBegan(touches, with: event)
}

只要我们将触摸移到按钮之外，移动信息就会发送到Keyboard类：

override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?)
{
    if let touch = touches.first
    {
        let point = touch.location(in: self)
        if !bounds.contains(point)
        {
            delegate?.onMoved(point: convert(point, to: superview))
            return
        }
    }

    super.touchesMoved(touches, with: event)
}

这是实际处理按钮字母的地方

override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?)
{
    if let touch = touches.first
    {
        let point = touch.location(in: self)
        delegate?.onEnded(point: convert(point, to: superview))
    }

    super.touchesEnded(touches, with: event)
}
}

正如我们所见，LetterButton 类建立了以下需要由 Keyboard 类实现的协议：

protocol LetterButtonDelegate
{
    func onBegan(button: LetterButton, point: CGPoint)
    func onMoved(point: CGPoint)
    func onEnded(point: CGPoint)
}

Keyboard 类中的协议实现如下：

最初被触摸的按钮存储在这里

func onBegan(button: LetterButton, point: CGPoint)
{
    buttonPressed = button
}

为我们滑动的按钮处理背景颜色变化

func onMoved(point: CGPoint)
{
    let _ = findPopupButton(point: point)
}

触摸结束的处理

func onEnded(point: CGPoint)
{
    // Check if touch ended on a popup button
    if let button = findPopupButton(point: point)
    {
        // yes, let the keyboard process the key
        delegate?.KeyPressed(key: button.title(for: .normal)!)
        button.setIsInside(val: false)

        // remove popupbuttons
        popupView?.removeFromSuperview()
        popupView = nil
    }
    else
    {
        // remove popup buttons if touch ended anywhere else
        if popupView != nil
        {
            popupView!.removeFromSuperview()
            popupView = nil

        }

        // buttons is an array of all normal keyboard buttons
        // we use it to check if the button, where the touch ended is the same where the touch began
        for button in buttons
        {
            if (button.frame.contains(point))
            {
                if (button.button.tag == buttonPressed?.tag)
                {
                    // Still on same button, process the key
                    delegate?.KeyPressed(key: button.button.title(for: .normal)!)              break
                }
            }
        }


    }
}


// Let's see if we are moving within the bounds of a popup button
func findPopupButton (point: CGPoint) -> LetterButton?
{
    var result : LetterButton? = nil

    if (popupView != nil)
    {
        if (popupView!.frame.contains(point))
        {
            for sub in popupView!.subviews
            {
                if (sub.isKind(of: LetterButton.self))
                {
                    let button = sub as! LetterButton
                    let frame = popupView!.convert(button.frame, to: self)

                    if (frame.contains(point))
                    {
                        button.setIsInside(val: true)
                        result = button
                    }
                    else
                    {
                        button.setIsInside(val: false)
                    }
                }
            }
        }
    }

    return result
}