Question

我想设置视图如何从屏幕底部滑动。但我不能这样做，而是从中心获得改变几何的动画。它看起来像这样

https://i.stack.imgur.com/aIYwC.gif

以下是

的观点

class Notes: UIView {

var topConstraint: NSLayoutConstraint?

lazy var overlay: UIView = {
    let view = UIView(frame: UIScreen.main.bounds)
    view.backgroundColor = .black
    view.alpha = 0.7
    view.autoresizingMask = [.flexibleWidth, .flexibleHeight]
    return view
}()

lazy var contentView: UIView = {
    let view = UIView()
    view.backgroundColor = .white
    view.alpha = 1
    view.translatesAutoresizingMaskIntoConstraints = false
    view.layer.cornerRadius = 5
    return view
}()

override init(frame: CGRect) {
    super.init(frame: UIScreen.main.bounds)

    setupViews()
}

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

func setupViews() {
    addSubview(overlay)
    addSubview(contentView)

    contentView.leftAnchor.constraint(equalTo: self.leftAnchor, constant: 16).isActive = true
    contentView.rightAnchor.constraint(equalTo: self.rightAnchor, constant: -16).isActive = true
    contentView.heightAnchor.constraint(equalToConstant: 400).isActive = true
    topConstraint = contentView.topAnchor.constraint(equalTo: self.topAnchor, constant: 800)

    topConstraint?.isActive = true
}

func animate() {

    self.topConstraint?.constant = 80

    UIView.animate(withDuration: 0.3, animations: {
        self.contentView.layoutIfNeeded()
    })
}

}

这就是我开球的方式

guard let window = UIApplication.shared.keyWindow else { return }
let notes = Notes()
window.addSubview(notes)
notes.animate()

我做错了什么？

Answer 1

您没有以正确的方式激活约束，也无法再次调用错误的布局视图

class Notes: UIView {

var topConstraint: NSLayoutConstraint?

lazy var overlay: UIView = {
    let view = UIView(frame: UIScreen.main.bounds)
    view.backgroundColor = .black
    view.alpha = 0.7
    view.autoresizingMask = [.flexibleWidth, .flexibleHeight]
    return view
}()

lazy var contentView: UIView = {
    let view = UIView()
    view.backgroundColor = .green
    view.alpha = 1
    view.translatesAutoresizingMaskIntoConstraints = false
    view.layer.cornerRadius = 5
    return view
}()

override init(frame: CGRect) {
    super.init(frame: UIScreen.main.bounds)

    setupViews()
}

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

func setupViews() {
    addSubview(overlay)
    addSubview(contentView)

    topConstraint = contentView.topAnchor.constraint(equalTo: self.topAnchor, constant: 800)
    // you can activate your constraints directly like this
    // I changed left and right to leading and trailing but that's a matter of choice
    // remember if your supporting left to right languages in your app then not use left and right better use Leading and Trailing
    NSLayoutConstraint.activate([
        contentView.leadingAnchor.constraint(equalTo: self.leadingAnchor, constant: 16),
        contentView.trailingAnchor.constraint(equalTo: self.trailingAnchor, constant: -16),
        contentView.heightAnchor.constraint(equalToConstant: 400),
        topConstraint!
        ])

}

func animate() {

    self.topConstraint?.constant = 80

    UIView.animate(withDuration: 0.3, animations: {
        // here you should call self.layoutIfNeeded so self which is a UIView should layout again
        self.layoutIfNeeded()
    })
  }



}

Answer 2

在self.layoutIfNeeded()功能结束时致电setupViews()。
在您的动画函数self.layoutIfNeeded()中，而不是内容视图。

休息一切都很好。

class Notes: UIView {

    var topConstraint: NSLayoutConstraint?

    lazy var overlay: UIView = {
        let view = UIView(frame: UIScreen.main.bounds)
        view.backgroundColor = .black
        view.alpha = 0.7
        view.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        return view
    }()

    lazy var contentView: UIView = {
        let view = UIView()
        view.backgroundColor = .white
        view.alpha = 1
        view.translatesAutoresizingMaskIntoConstraints = false
        view.layer.cornerRadius = 5
        return view
    }()

    override init(frame: CGRect) {
        super.init(frame: UIScreen.main.bounds)

        setupViews()
    }

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

    func setupViews() {
        addSubview(overlay)
        addSubview(contentView)

        contentView.leftAnchor.constraint(equalTo: self.leftAnchor, constant: 16).isActive = true
        contentView.rightAnchor.constraint(equalTo: self.rightAnchor, constant: -16).isActive = true
        contentView.heightAnchor.constraint(equalToConstant: 400).isActive = true
        topConstraint = contentView.topAnchor.constraint(equalTo: self.topAnchor, constant: 800)

        topConstraint?.isActive = true
        self.layoutIfNeeded()
    }

    func animate() {

        self.topConstraint?.constant = 80

        UIView.animate(withDuration: 0.3, animations: {
            self.layoutIfNeeded()
        })
    }
}

错误的约束动画

2 个答案: