在 Swift 中选择时如何将子视图置于前面？

Question

所以我有两个视图，都以编程方式添加到超级视图中：

//First added view to my superView (baseView)
let imageViewOne = UIImageView(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
baseView.addSubview(imageViewOne)
//Second added view to my superView (baseView)
let imageViewTwo = UIImageView(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
baseView.addSubview(imageViewTwo)

我想在选中其中一个视图时将其置于最前面，因为当您添加新视图时，它会与前一个视图重叠。适用于“选择”或“触摸”的东西。

Answer 1

使用这个：

baseView.bringSubview(toFront: imageViewOne)

Answer 2

您可以通过 UITapGestureRecognizer 通过从界面生成器设置恢复 ID 来完成此操作

func tapOneAct(sender: UITapGestureRecognizer) {
    if(sender.view!.restorationIdentifier == "view1") 
    // view1 is `Restoration ID` of imageViewOne
    {
        view.bringSubview(toFront: imageViewOne)
    }
    if(sender.view!.restorationIdentifier == "view2")
    // view2 is `Restoration ID` of 2nd view
    {
        view.bringSubview(toFront: imageViewTwo)
    }
}

Answer 3

如果我理解正确，那么您想检查所选视图的状态并将其置于视图层次结构的前面。 在这种情况下，您必须执行以下操作：

1) 曲目选择状态，在代码sn-p中设为var isSelected: Bool

2) 当视图被选中时，为一个动作保持回调（你可以使用例如UIButton 来观察点击事件）

在下面的代码 sn-p 中，您可以检查触摸视图时的选择状态。

BaseView 实现了检查SelectionView 状态的逻辑。

import UIKit

final class SelectionView<T: UIView>: UIView {

    var onTap: ((_ isSelected: Bool) -> ())?

    // MARK: - Private

    private let view: T
    private let button = UIButton(type: .custom)
    private var isSelected: Bool = false

    // MARK: - Init

    init(view: T) {
        self.view = view

        super.init(frame: .zero)

        setUp()
    }

    // MARK: - Private

    private func setUp() {
        addSubview(view)
        addSubview(button)

        button.addTarget(self, action: #selector(onButtonTap), for: .touchUpInside)
    }

    @objc private func onButtonTap() {
        isSelected = !isSelected

        onTap?(isSelected)
    }

    // MARK: - Layout

    override func layoutSubviews() {
        super.layoutSubviews()

        view.frame = bounds
        button.frame = bounds
    }

    override func sizeThatFits(_ size: CGSize) -> CGSize {
        return view.sizeThatFits(size)
    }

    // MARK: - Unused

    override init(frame: CGRect) {
        fatalError("init(frame:) has not been implemented")
    }

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

final class BaseView: UIView {

    init() {
        super.init(frame: .zero)

        let views = [SelectionView(view: UIView()), SelectionView(view: UIView())]
        for view in views {
            view.onTap = { [weak self, weak view] isSelected in
                guard let selectedView = view
                    else { return }

                if isSelected {
                    self?.bringSubview(toFront: selectedView)
                }
            }
        }
    }

    // MARK: - Unused

    override init(frame: CGRect) {
        fatalError("init(frame:) has not been implemented")
    }

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