Swift - 不为空时自动跳转到下一个文本字段

Question

我正在开发一款游戏，用户必须在其中输入动词的过去式。我的 View 包含只接受一个字符的小文本框。截至目前，当前者包含字母时，我正在尝试自动跳转到下一个文本字段。

我想一直这样做，直到所有的盒子都被填满。用户还应该能够使用键盘上的返回按钮返回一个框。

下面是我目前正在使用的代码，但它没有跳转到下一个文本字段。我做错了什么？

 var game: Game? {
    didSet {

        if var answerContent = game?.answer {

            let views = (0..<answerContent.characters.count).map { _ in UITextField(frame: CGRect(x: 0, y: 0, width: 40, height: 40)) }

            for textField in views {
                textField.backgroundColor = UIColor.white
                textField.textColor = Constants.MAIN_THEME_COLOR
                textField.textAlignment = NSTextAlignment.center
                textField.delegate = self
                textField.returnKeyType = .next
                textField.tag = views.index(of: textField)! + 1
                self.container.addArrangedSubview(textField)

                views.first?.becomeFirstResponder()
            }
        }
    }
}

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    guard let text = textField.text else { return true }
    let textLength = text.characters.count + string.characters.count - range.length

    return textLength <= 1
}

func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        if let nextField = textField.superview?.viewWithTag(textField.tag + 1) as? UITextField {
            print("Test")
            nextField.becomeFirstResponder()
        } else {
            print("Test2")
            textField.resignFirstResponder()
        }

    return false
}

更新代码 (24-04-2017) - 尝试跳转到下一个文本字段时返回 nil

var game: Game? {
    didSet {

if var answerContent = game?.answer {

            let views = (0..<answerContent.characters.count).map { _ in UITextField(frame: CGRect(x: 0, y: 0, width: 40, height: 40)) }

            for textField in views {
                textField.backgroundColor = UIColor.white
                textField.textColor = Constants.MAIN_THEME_COLOR
                textField.textAlignment = NSTextAlignment.center
                textField.delegate = self
                textField.addTarget(self, action: #selector(textChanged), for: .editingChanged)
                textField.tag = views.index(of: textField)! + 1
                self.container.addArrangedSubview(textField)
            }

            views.first?.becomeFirstResponder()
        }
    }
}

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    guard let text = textField.text else { return true }
    let textLength = text.characters.count + string.characters.count - range.length

    return textLength <= 1
}

func textChanged(sender: UITextField) {
    if (sender.text?.characters.count)! > 0 {
        print("Entered")
        let nextField = textField?.superview?.viewWithTag(textField.tag + 1) as UIResponder!

        if (nextField != nil) {
            nextField?.becomeFirstResponder()
        } else {
            print("Error: nil found")
        }
    } else {
        print("Removed")
        textField?.resignFirstResponder()
    }
}

回答:

var index: NSInteger = 0
for textField in views {
    textField.backgroundColor = UIColor.white
    textField.textColor = Constants.MAIN_THEME_COLOR
    textField.textAlignment = NSTextAlignment.center
    textField.autocapitalizationType = UITextAutocapitalizationType.none
    textField.delegate = self
    textField.addTarget(self, action: #selector(textChanged), for: .editingChanged)
    textField.tag = index
    self.container.addArrangedSubview(textField)

    index+=1
}

func textChanged(sender: UITextField) {
    if (sender.text?.characters.count)! > 0 {
        let nextField = sender.superview?.viewWithTag(sender.tag + 1) as UIResponder!
        nextField?.becomeFirstResponder()
    } else {
        sender.resignFirstResponder()
    }
}

Answer 1

我建议你应该给控制事件添加一个目标.valueChanged:

// for each text field
textField.addTarget(self, action: #selector(textChanged), for: .valueChanged)

按如下方式实现textChanged:

func textChanged(sender: UITextField) {
    if sender.text.characters.length > 0 {
        let nextField = textField.superview?.viewWithTag(textField.tag + 1) as? UITextField
        nextField?.becomeFistResponder()
    }
}