如何在 Swift 中修复 textView.resignFirstResponder() 崩溃

Question

非常简单的程序，它会显示一个数字键盘，当用户单击它时，我想将其关闭。

我有 ViewController： UIViewController， UITextFieldDelegate

inputField.delegate = self

和

inputField.resignFirstResponder() inside of touchesBegan

但是，每当我在数字键盘之外触摸时，该应用程序都会在模拟器中崩溃。

我尝试将inputField.resignFirstResponder((放在按钮操作中，该操作现在也会触发崩溃(仅当数字键盘首次被打开时(。

import UIKit
class ViewController: UIViewController, UITextFieldDelegate {
    override func viewDidLoad() {
        super.viewDidLoad()
        inputField.delegate = self
        // Do any additional setup after loading the view.
    }
    @IBOutlet weak var inputField: UITextField!
    @IBOutlet weak var outputLabel: UILabel!
    @IBAction func buttonPress(_ sender: UIButton) {
        inputField.resignFirstResponder()
        outputLabel.text = "Your stamp duty will be: £1,750"
    }
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        inputField.resignFirstResponder()
    }
}

我在调试器中得到以下内容：

2019-06-08 17:23:19.945120+0100 StampDutyCalc[2104:180233] [MC] Reading from private effective user settings.
2019-06-08 17:23:19.976471+0100 StampDutyCalc[2104:180233] Can't find keyplane that supports type 4 for keyboard iPhone-PortraitTruffle-NumberPad; using 20615_PortraitTruffle_iPhone-Simple-Pad_Default
2019-06-08 17:23:20.834475+0100 StampDutyCalc[2104:180233] -[StampDutyCalc.ViewController inputField:]: unrecognized selector sent to instance 0x7fb26c517040
2019-06-08 17:23:20.844880+0100 StampDutyCalc[2104:180233] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[StampDutyCalc.ViewController inputField:]: unrecognized selector sent to instance 0x7fb26c517040'

Answer 1

您可能不想覆盖touchesBegan。您可能只想使用UITapGestureRecognizer .

这是我用来在用户点击其他地方时关闭键盘的扩展：

extension UIViewController {
    /// Hides the keyboard when you tap anywhere in the view that doesnt have its own tap recognizer. Ex: the view behind a button or text field.
    func hideKeyboardWhenTappedAround() {
        let tap: UITapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(UIViewController.dismissKeyboard))
        tap.cancelsTouchesInView = false
        view.addGestureRecognizer(tap)
    }
    @objc func dismissKeyboard() {
        view.endEditing(true)
    }
}

现在只需致电：

MyViewController.hideKeyboardWhenTappedAround()

或者，您可以直接在 VC 上应用该代码，但我喜欢使用扩展进行重用。