Swift - 不为空时自动跳转到下一个文本字段

Question

我正在开发一个游戏，用户必须输入动词的过去时。我的视图包含只接受一个字符的小文本框。截至目前，当前者包含一个字母时，我正试图自动跳转到下一个文本字段。

我想继续这样做，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。

下面是我当前使用的代码，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()
    }
}

答案：

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

我建议你应该在控制事件.valueChanged中添加一个目标：

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

如下实现textChanged：

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

Answer 2

关注代码：

import UIKit

// used this to set max characters of UITextField in the storyboard
private var __maxLengths = [UITextField: Int]()
extension UITextField {
    @IBInspectable var maxLength: Int {
        get {
            guard let l = __maxLengths[self] else {
                return 150 // (global default-limit. or just, Int.max)
            }
            return l
        }
        set {
            __maxLengths[self] = newValue
            addTarget(self, action: #selector(fix), for: .editingChanged)
        }
    }
    func fix(textField: UITextField) {
        let t = textField.text
        textField.text = t?.safelyLimitedTo(length: maxLength)
    }
}

extension String
{
    func safelyLimitedTo(length n: Int)->String {
        let c = self.characters
        if (c.count <= n) { return self }
        return String( Array(c).prefix(upTo: n) )
    }
}


class ViewController: UIViewController {

  @IBOutlet var input1: UITextField!
  @IBOutlet var input2: UITextField!
  @IBOutlet var input3: UITextField!
  @IBOutlet var input4: UITextField!
  @IBOutlet var input5: UITextField!
  @IBOutlet var input6: UITextField!

  override func viewDidLoad() {
        super.viewDidLoad()

        setup()
        // Do any additional setup after loading the view.
  }

  func setup() {
        input1.tag = 1
        input2.tag = 2
        input3.tag = 3
        input4.tag = 4
        input5.tag = 5
        input6.tag = 6

        input1.addTarget(self, action: #selector(textChanged), for: .editingChanged)
        input2.addTarget(self, action: #selector(textChanged), for: .editingChanged)
        input3.addTarget(self, action: #selector(textChanged), for: .editingChanged)
        input4.addTarget(self, action: #selector(textChanged), for: .editingChanged)
        input5.addTarget(self, action: #selector(textChanged), for: .editingChanged)
        input6.addTarget(self, action: #selector(textChanged), for: .editingChanged)
  }

  func textChanged(sender: UITextField) {
        if (sender.text?.characters.count)! ==  1 {

            let nextField = sender.superview?.viewWithTag(sender.tag + 1) as UIResponder!
            nextField?.becomeFirstResponder()
        } else if (sender.text?.characters.count)! ==  0 {
            let nextField = sender.superview?.viewWithTag(sender.tag - 1) as UIResponder!
            nextField?.becomeFirstResponder()
        }


    }


}

Answer 3

Swift 4 更新

在viewDidLoad() 中为每个文本字段，

textField.addTarget(self, action: #selector(textChanged), for: .editingChanged)

然后，添加这个函数，

@objc func textChanged(sender: UITextField) {
    if (sender.text?.count)! > 0 {
        let nextField = self.view.viewWithTag(sender.tag + 1) as? UITextField
        nextField?.becomeFirstResponder()
    }
}