Swift 添加到文本字段的手势识别器在成为第一响应者后无法操作？

Question

我在 swift 中的文本字段中添加了点击和双击手势识别器，因此单击执行功能但双击实际上使文本字段成为第一响应者。虽然在文本字段第一次成为第一响应者后它停止工作。也就是说，文本字段通过单击而不是双击成为第一响应者来正常运行。关于如何让我的手势识别器正常工作有什么想法吗？

Answer 1

从逻辑上讲，如果您改为执行以下步骤会更容易：

将 texField 设置为 "editable" false
在 doubleTap 操作实现上使文本字段可编辑为 true 并调用 becomeFirstResponder 以便用户可以键入。
实施文本字段委托方法 -textFieldDidEndEditing 并通过将 "editable" 属性设置为 false 再次使该文本字段不可编辑。

Answer 2

另一种方法：

只需在文本字段顶部创建一个 'invisible' 视图并向其中添加手势识别器

    import UIKit

    class ViewController: UIViewController, UITextFieldDelegate {

        @IBOutlet weak var textField: UITextField!

        override func viewDidLoad() {
            super.viewDidLoad()
            textField.delegate = self;
        }

        override func viewDidAppear(animated: Bool) {
            let tap1 = UITapGestureRecognizer(target: self, action: "onSingleTap")
            let tap2 = UITapGestureRecognizer(target: self, action: "onDoubleTap")
            tap2.numberOfTapsRequired = 2

            // create a view and put it on top of the textfield
            // here created at viewDidAppear for example but you can do it better

            var dummieView = UIView(frame: self.textField.frame)
            dummieView.backgroundColor = UIColor(red: 1.0, green: 0.0, blue: 0.0, alpha: 0.25)
            self.view.addSubview(dummieView)
            dummieView.addGestureRecognizer(tap1)
            dummieView.addGestureRecognizer(tap2)
        }

        func onSingleTap(){
            println("custom single tap")
            if self.textField.isFirstResponder() {
                self.textField.resignFirstResponder()
            }
        }

        func onDoubleTap(){
            println("double tap")
            self.textField.becomeFirstResponder()
        }

        func textFieldShouldReturn(textField: UITextField) -> Bool {
            if self.textField.isFirstResponder() {
                self.textField.resignFirstResponder()
            }
            return true
        }


    }

Answer 3

我有类似的问题，想要通过单击来交替显示和隐藏 UIPicker。

问题是 UITextField 添加了自己的手势识别器。因此，subclass UITextField 并添加您自己的，但不允许添加默认手势识别器。

class MyTextField: UITextField
{
    fileprivate var tap1Gesture: UITapGestureRecognizer?
    fileprivate var tap2Gesture: UITapGestureRecognizer?

    required init?( coder aDecoder: NSCoder )
    {
        super.init( coder: aDecoder )

        gestureRecognizers = nil
        tap1Gesture = UITapGestureRecognizer( target: self, action: #selector( tapped1( _: ) ) )
        addGestureRecognizer( tap1Gesture! )
        tap2Gesture = UITapGestureRecognizer( target: self, action: #selector( tapped2( _: ) ) )
        tap2Gesture.numberOfTapsRequired = 2
        addGestureRecognizer( tap2Gesture! )
    }

    override func addGestureRecognizer(_ gestureRecognizer: UIGestureRecognizer)
    {
        if gestureRecognizer == tap1Gesture || gestureRecognizer == tap2Gesture
        {
            super.addGestureRecognizer( gestureRecognizer )
        }
    }

    internal func tapped1( _ sender: UITapGestureRecognizer )
    {
        // Do your "performs a function"
    }

    internal func tapped2( _ sender: UITapGestureRecognizer )
    {
        if self.isFirstResponder
        {
            _ = self.resignFirstResponder()
        }
        else
        {
            self.becomeFirstResponder()
        }
    }
}

如果您想隐藏文本选择，您还可以将以下内容添加到派生的 class（借助帮助 http://www.b2cloud.com.au/tutorial/disabling-the-caret-and-text-entry-in-uitextfields/）：

extension MyTextField
{
    override var selectedTextRange: UITextRange?
    {
        get { return nil }
        set { return }
    }

    override func canPerformAction( _ action: Selector, withSender sender: Any? ) -> Bool
    {
        return false
    }

    override func caretRect( for position: UITextPosition ) -> CGRect
    {
        return .zero
    }
}

Swift 添加到文本字段的手势识别器在成为第一响应者后无法操作？

Swift Gesture recognizers added to textfield inoperable after becomes first responder?

tap

uitextfield

uigesturerecognizer

swift