ios - 用户打字时覆盖变暗

Question

当用户点击文本字段时，我想使屏幕的其余部分(文本框下方、键盘上方的所有内容)变暗，以明确他们应该做什么。我相信它涉及放下透明的 UI View 并向其添加手势识别器，但我不太确定该怎么做。

当用户到达屏幕时，我有以下代码。这是我要添加新 UI View 的地方吗？

override func viewWillAppear(animated: Bool) {
  super.viewWillAppear(animated)
  textField.becomeFirstResponder()
}

谢谢!

Answer 1

我创建了 UIView 的子类有两个原因:

• 你可以给它添加一个手势识别器
• 你可以给它添加一个委托(delegate)

因为添加到 View 的最后一个 subview 在顶部，所以我首先添加深色层，然后调用 bringSubviewToFront(textview) 这会将深色层放在相关的 textview 和其他所有内容之间。

我创建了一个只有一个功能的协议(protocol)。此函数由手势识别器调用，并将 DarkView 的实例返回给委托(delegate)。委托(delegate)(您的 ViewController)然后可以将其从其 super View 中删除。您可以在没有委托(delegate)函数的情况下执行此操作，但您还必须在文本字段上调用 ​​resignFirstResponder()。

不要忘记在您的 ViewController 中设置 DarkView 的委托(delegate)。

只是一个带有一些文本字段的 VC。

class FirstViewController: UIViewController, DarkViewDelegate, UITextFieldDelegate {

    var masterView : UIView!

    override func viewDidLoad() {

        super.viewDidLoad()

        masterView = UIView(frame: self.view.frame)
        masterView.backgroundColor = UIColor.whiteColor()

        let textField1 = UITextField(frame: CGRect(x: 50, y: 20, width: 300, height: 20))
        let textField2 = UITextField(frame: CGRect(x: 50, y: 60, width: 300, height: 20))
        let textField3 = UITextField(frame: CGRect(x: 50, y: 100, width: 300, height: 20))
        let textField4 = UITextField(frame: CGRect(x: 50, y: 140, width: 300, height: 20))

        func styleTextField(field : UITextField) {
            field.layer.borderColor = UIColor.blackColor().CGColor
            field.layer.borderWidth = 2
            field.layer.cornerRadius = field.frame.size.height / 2
            field.backgroundColor = UIColor.whiteColor()
            field.delegate = self
            masterView.addSubview(field)
        }

        styleTextField(textField1)
        styleTextField(textField2)
        styleTextField(textField3)
        styleTextField(textField4)

        self.view.addSubview(masterView)
        // Do any additional setup after loading the view, typically from a nib.

    }

    // delegate function of a textfield 
    func textFieldDidBeginEditing(textField: UITextField) {
        focusUserOn(textField) // darken everything else
    }

    // delegate function of DarkView undarken everything
    func tappedDark(view: DarkView) {

        guard let superV = view.superview else {
            return
        }

        if let textField = superV.subviews.last as? UITextField {
            textField.resignFirstResponder() // also stop editing
        }

        view.removeFromSuperview()
    }

    func focusUserOn(textfield: UITextField) {

        guard let superV = textfield.superview else {
            return
        }

        let darkArea = DarkView(frame: superV.bounds)
        darkArea.delegate = self
        superV.addSubview(darkArea)// add DarkView (everything is dark now)

        superV.bringSubviewToFront(textfield) // bring the textview back to the front.
    }

}

带有手势识别器的 UIView 的简单子(monad)类

class DarkView : UIView, UIGestureRecognizerDelegate {

    weak var delegate : DarkViewDelegate?

    override init(frame: CGRect) {
        super.init(frame: frame)
        backgroundColor = UIColor(red: 0.0, green: 0.0, blue: 0.0, alpha: 0.4)
        let tap = UITapGestureRecognizer(target: self, action: Selector("tapped"))
        tap.delegate = self
        self.addGestureRecognizer(tap)
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    deinit {
        print("deinit dark")
    }

    func tapped() {
        guard let del = self.delegate else {
            return
        }
        del.tappedDark(self)
    }
}

当 DarkView 被点击到 VC 时传递 DarkView 的协议(protocol)

protocol DarkViewDelegate : class {

    func tappedDark(view:DarkView)

}

深思熟虑

func textFieldDidEndEditing(textField: UITextField) {
    guard let superV = view.superview else {
        return
    }

    for subview in superV.subviews {

        if subview is DarkView {
            subview.removeFromSuperview()
        }

    }
}