我有一个视图，上面有一个按钮，下面有一个textview作为子视图，我试图让按钮展开并显示textview或者折叠并隐藏它（像show/hide）
我在这里使用了解决方案，它有点帮助，除了子视图（文本视图）仍然显示并且与其他视图重叠，所以它只隐藏了主UIView。
这里我将height约束初始化为25，以便为按钮留出空间:heightConstraint=detailView.heightanchor.constraint（equaltoConstant:25）
基于高度约束展开/折叠视图的操作函数
@objc func expandViewPressed(sender: UIButton) {
if isAnimating { return }
let shouldCollapse = detailView.frame.height > 25
animateView(isCollapsed: shouldCollapse)
}
动画功能
private func animateView(isCollapsed: Bool) {
heightConstraint[enter image description here][1].isActive = isCollapsed
isAnimating = true
UIView.animate(withDuration: 1, animations: {
self.detailText.isHidden = isCollapsed
self.view.layoutIfNeeded()
}) { (_) in
self.isAnimating = false
}
}
-
展开视图
谢尔比尼。 请确保已为子视图添加了适当的约束。 确保不要在任何子视图上添加高度限制。
还要确保添加了view.clipstobounds==true
希望对你有用。
有各种方法来处理这个问题。
一种方法是使用两个“底”约束:
DetailViewDetailText的底部到DetailView然后根据视图应该“折叠”还是“展开”设置每个视图的约束优先级。
下面是一个完整的实现，供您尝试:
class ExpandViewController: UIViewController {
let myButton: UIButton = {
let v = UIButton()
v.translatesAutoresizingMaskIntoConstraints = false
v.setTitle("Collapse", for: [])
v.backgroundColor = .red
return v
}()
let detailText: UITextView = {
let v = UITextView()
v.translatesAutoresizingMaskIntoConstraints = false
v.text = "This is text in the text view."
return v
}()
let detailView: UIView = {
let v = UIView()
v.translatesAutoresizingMaskIntoConstraints = false
v.backgroundColor = UIColor(red: 0.25, green: 0.5, blue: 1.0, alpha: 1.0)
v.clipsToBounds = true
return v
}()
var isAnimating: Bool = false
var collapsedConstraint: NSLayoutConstraint!
var expandedConstraint: NSLayoutConstraint!
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = UIColor(red: 0.0, green: 0.75, blue: 0.0, alpha: 1.0)
detailView.addSubview(myButton)
detailView.addSubview(detailText)
view.addSubview(detailView)
let g = view.safeAreaLayoutGuide
// when collapsed, we want button bottom to constrain detailView bottom
collapsedConstraint = myButton.bottomAnchor.constraint(equalTo: detailView.bottomAnchor, constant: -12.0)
// when expanded, we want textView bottom to constrain detailView bottom
expandedConstraint = detailText.bottomAnchor.constraint(equalTo: detailView.bottomAnchor, constant: -12.0)
// we'll start in Expanded state
expandedConstraint.priority = .defaultHigh
collapsedConstraint.priority = .defaultLow
NSLayoutConstraint.activate([
// constrain detailView Top / Leading / Trailing
detailView.topAnchor.constraint(equalTo: g.topAnchor, constant: 20.0),
detailView.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 40.0),
detailView.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -40.0),
// no Height or Bottom constraint for detailView
// constrain button Top / Center / Width
myButton.topAnchor.constraint(equalTo: detailView.topAnchor, constant: 12.0),
myButton.centerXAnchor.constraint(equalTo: detailView.centerXAnchor),
myButton.widthAnchor.constraint(equalToConstant: 200.0),
// constrain detailText Top / Leading / Trailing
detailText.topAnchor.constraint(equalTo: myButton.bottomAnchor, constant: 12.0),
detailText.leadingAnchor.constraint(equalTo: detailView.leadingAnchor, constant: 12.0),
detailText.trailingAnchor.constraint(equalTo: detailView.trailingAnchor, constant: -12.0),
// constrain detailText's Height
detailText.heightAnchor.constraint(equalToConstant: 200.0),
expandedConstraint,
collapsedConstraint,
])
myButton.addTarget(self, action: #selector(self.expandViewPressed(sender:)), for: .touchUpInside)
}
@objc func expandViewPressed(sender: UIButton) {
if isAnimating { return }
animateView()
}
private func animateView() {
isAnimating = true
// if it's expanded
if expandedConstraint.priority == .defaultHigh {
expandedConstraint.priority = .defaultLow
collapsedConstraint.priority = .defaultHigh
} else {
collapsedConstraint.priority = .defaultLow
expandedConstraint.priority = .defaultHigh
detailText.isHidden = false
}
UIView.animate(withDuration: 1, animations: {
self.view.layoutIfNeeded()
}) { (_) in
self.detailText.isHidden = self.expandedConstraint.priority == .defaultLow
self.isAnimating = false
self.myButton.setTitle(self.detailText.isHidden ? "Expand" : "Collapse", for: [])
}
}
}
