不要害怕这里的巨大代码.您可以将代码段复制并粘贴到新的单一视图应用程序中,以查看其行为.该问题位于与旋转动画一起执行的动画完成块内的某处.
import UIKit
let sizeConstant: CGFloat = 60
class ViewController: UIViewController {
let topView = UIView()
let backgroundView = UIView()
let stackView = UIStackView()
let lLayoutGuide = UILayoutGuide()
let bLayoutGuide = UILayoutGuide()
var bottomConstraints = [NSLayoutConstraint]()
var leftConstraints = [NSLayoutConstraint]()
var bLayoutHeightConstraint: NSLayoutConstraint!
var lLayoutWidthConstraint: NSLayoutConstraint!
override func viewDidLoad() {
super.viewDidLoad()
print(UIScreen.main.bounds)
// self.view.layer.masksToBounds = true
let views = [
UIButton(type: .infoDark),UIButton(type: .contactAdd),UIButton(type: .detailDisclosure)
]
views.forEach(self.stackView.addArrangedSubview)
self.backgroundView.backgroundColor = UIColor.red
self.backgroundView.translatesAutoresizingMaskIntoConstraints = false
self.view.addSubview(self.backgroundView)
self.topView.backgroundColor = UIColor.green
self.topView.translatesAutoresizingMaskIntoConstraints = false
self.view.addSubview(self.topView)
self.stackView.axis = isPortrait() ? .horizontal : .vertical
self.stackView.distribution = .fillEqually
self.stackView.translatesAutoresizingMaskIntoConstraints = false
self.backgroundView.addSubview(self.stackView)
self.topView.topAnchor.constraint(equalTo: self.topLayoutGuide.bottomAnchor).isActive = true
self.topView.leadingAnchor.constraint(equalTo: self.view.leadingAnchor).isActive = true
self.topView.trailingAnchor.constraint(equalTo: self.view.trailingAnchor).isActive = true
self.topView.heightAnchor.constraint(equalToConstant: 46).isActive = true
self.view.addLayoutGuide(self.lLayoutGuide)
self.view.addLayoutGuide(self.bLayoutGuide)
self.bLayoutGuide.bottomAnchor.constraint(equalTo: self.view.bottomAnchor).isActive = true
self.bLayoutGuide.leadingAnchor.constraint(equalTo: self.view.leadingAnchor).isActive = true
self.bLayoutGuide.trailingAnchor.constraint(equalTo: self.view.trailingAnchor).isActive = true
self.bLayoutHeightConstraint = self.bLayoutGuide.heightAnchor.constraint(equalToConstant: isPortrait() ? sizeConstant : 0)
self.bLayoutHeightConstraint.isActive = true
self.lLayoutGuide.topAnchor.constraint(equalTo: self.topView.bottomAnchor).isActive = true
self.lLayoutGuide.bottomAnchor.constraint(equalTo: self.view.bottomAnchor).isActive = true
self.lLayoutGuide.leadingAnchor.constraint(equalTo: self.view.leadingAnchor).isActive = true
self.lLayoutWidthConstraint = self.lLayoutGuide.widthAnchor.constraint(equalToConstant: isPortrait() ? 0 : sizeConstant)
self.lLayoutWidthConstraint.isActive = true
self.stackView.topAnchor.constraint(equalTo: self.backgroundView.topAnchor).isActive = true
self.stackView.bottomAnchor.constraint(equalTo: self.backgroundView.bottomAnchor).isActive = true
self.stackView.leadingAnchor.constraint(equalTo: self.backgroundView.leadingAnchor).isActive = true
self.stackView.trailingAnchor.constraint(equalTo: self.backgroundView.trailingAnchor).isActive = true
self.bottomConstraints = [
self.backgroundView.topAnchor.constraint(equalTo: self.bLayoutGuide.topAnchor),self.backgroundView.leadingAnchor.constraint(equalTo: self.bLayoutGuide.leadingAnchor),self.backgroundView.trailingAnchor.constraint(equalTo: self.bLayoutGuide.trailingAnchor),self.backgroundView.heightAnchor.constraint(equalToConstant: sizeConstant)
]
self.leftConstraints = [
self.backgroundView.topAnchor.constraint(equalTo: self.lLayoutGuide.topAnchor),self.backgroundView.bottomAnchor.constraint(equalTo: self.lLayoutGuide.bottomAnchor),self.backgroundView.trailingAnchor.constraint(equalTo: self.lLayoutGuide.trailingAnchor),self.backgroundView.widthAnchor.constraint(equalToConstant: sizeConstant)
]
if isPortrait() {
NSLayoutConstraint.activate(self.bottomConstraints)
} else {
NSLayoutConstraint.activate(self.leftConstraints)
}
}
override func viewWillTransition(to size: CGSize,with coordinator: UIViewControllerTransitionCoordinator) {
let willBePortrait = size.width < size.height
coordinator.animate(alongsideTransition: {
context in
let halfDuration = context.transitionDuration / 2.0
UIView.animate(withDuration: halfDuration,delay: 0,options: .overrideInheritedDuration,animations: {
self.bLayoutHeightConstraint.constant = 0
self.lLayoutWidthConstraint.constant = 0
self.view.layoutIfNeeded()
},completion: {
_ in
// HERE IS THE ISSUE!
// Putting this inside `performWithoutAnimation` did not helped
if willBePortrait {
self.stackView.axis = .horizontal
NSLayoutConstraint.deactivate(self.leftConstraints)
NSLayoutConstraint.activate(self.bottomConstraints)
} else {
self.stackView.axis = .vertical
NSLayoutConstraint.deactivate(self.bottomConstraints)
NSLayoutConstraint.activate(self.leftConstraints)
}
self.view.layoutIfNeeded()
UIView.animate(withDuration: halfDuration) {
if willBePortrait {
self.bLayoutHeightConstraint.constant = sizeConstant
} else {
self.lLayoutWidthConstraint.constant = sizeConstant
}
self.view.layoutIfNeeded()
}
})
})
super.viewWillTransition(to: size,with: coordinator)
}
func isPortrait() -> Bool {
let size = UIScreen.main.bounds.size
return size.width < size.height
}
}
以下是我无法解决的问题的几个截图.仔细观察角落：
我会假设在重新激活不同的约束阵列和强制重新计算之后,视图将立即捕捉到布局指南,但如图所示.此外,我不明白为什么红色视图与堆栈视图不同步,即使stackview应该始终遵循它的superview,这是红色视图.
PS：测试它的最好方法是iPhone X Plus模拟器.
解决方法
使用大小类
一个完全不同的方法来平滑地动画化工具栏动画是利用autoLayout大小类,特别是hR(高度常规)和hC(高度紧凑),并为每个类别创建不同的约束.
>进一步的改进是实际使用两个不同的工具栏,一个用于垂直显示,一个用于水平显示.这并不意味着一个要求,但它解决了工具栏本身的大小(†).
>最后的改进是在Interface Builder中实现这些更改,只产生0行代码,这当然也不是强制的.
零行代码
UIViewControllerTransitionCoordinator所提出的解决方案都没有改进,这不仅大大简化了源代码开发和维护,而且还不需要依靠硬编码的值或支持的实用程序.您还可以在Interface Builder中预览.一旦在IB中完成,您仍然可以将逻辑转换为运行时编程,如果它是绝对要求.
>请注意,UIStackView嵌入在工具栏中,因此遵循动画.您可以通过常数来控制工具栏的摆动量;我选择1024,以便他们快速移出屏幕,只有在转换结束时才会重新出现.
>(†)进一步利用Interface Builder和大小类,您仍然可以使用单个工具栏,但如果这样做,它将在转换过程中调整大小.再次,UIStackView是嵌入式的,并且它的方向也是依赖于大小类,并且操作系统处理所有动画,而不需要创建协调器：
►在GitHub查找此解决方案,并在Swift Recipes上查看更多详细信息.
