我使用NSLayout锚创建了一个高度为100的视图。当我尝试更新按钮单击时,它不起作用。
我已经尝试了下面的代码,但是没有用。
class ViewController: UIViewController {
@IBOutlet weak var button: UIButton!
let viewAnimate = UIView()
var isHidden = false
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(viewAnimate)
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
viewAnimate.translatesAutoresizingMaskIntoConstraints = false
viewAnimate.leadingAnchor.constraint(equalTo: self.view.leadingAnchor, constant: 8).isActive = true
viewAnimate.trailingAnchor.constraint(equalTo: self.view.trailingAnchor, constant: -8).isActive = true
viewAnimate.topAnchor.constraint(equalTo: self.view.topAnchor, constant: 100).isActive = true
viewAnimate.heightAnchor.constraint(equalToConstant: 100).isActive = true
viewAnimate.backgroundColor = UIColor.red
}
@IBAction func show() {
if !isHidden {
viewAnimate.topAnchor.constraint(equalTo: self.view.topAnchor, constant: 200).isActive = true
button.setTitle("Show", for: .normal)
} else {
button.setTitle("Hide", for: .normal)
viewAnimate.topAnchor.constraint(equalTo: self.view.topAnchor, constant: 100).isActive = true
}
UIView.animate(withDuration: 1) {
self.viewAnimate.layoutIfNeeded()
}
isHidden = !isHidden
}
}
视图应根据高度限制更改高度
最佳答案
您的当前代码会产生冲突,因为像viewAnimate.topAnchor.constraint(equalTo:
这样的每一行都会添加一个新约束,创建一个变量
var topCon:NSLayoutConstraint!
topCon = viewAnimate.topAnchor.constraint(equalTo: self.view.topAnchor, constant: 100)
topCon.isActive = true
@IBAction func show() {
if !isHidden {
topCon.constant = 200
button.setTitle("Show", for: .normal)
} else {
button.setTitle("Hide", for: .normal)
topCon.constant = 100
}
UIView.animate(withDuration: 1) {
self.view.layoutIfNeeded()
}
isHidden = !isHidden
}
关于ios - 更新布局 anchor 无法正常工作,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/57868174/