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如果您只是呈现另一个视图控制器的视图，将动画更改为翻转的简单解决方案是在目标视图控制器中设置modalTransitionStyle。您可以完全在界面生成器中的 segue 属性下完成此操作。
如果您想以编程方式执行此操作，则可以在目标控制器中在 Swift 3 中执行以下操作：
override func viewDidLoad() {
super.viewDidLoad()
modalTransitionStyle = .flipHorizontal // use `.FlipHorizontal` in Swift 2
}
然后，当您调用show/showViewController 或present/presentViewController 时，您的演示文稿将进行水平翻转。而且，当您关闭视图控制器时，动画会自动为您反转。
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如果您需要更多控制，在 iOS 7 及更高版本中，您将使用自定义动画过渡，您可以在其中指定 modalPresentationStyle 或 .custom。例如，在 Swift 3 中：
class SecondViewController: UIViewController {
let customTransitionDelegate = TransitioningDelegate()
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
modalPresentationStyle = .custom // use `.Custom` in Swift 2
transitioningDelegate = customTransitionDelegate
}
...
}
指定将实例化动画控制器的UIViewControllerTransitioningDelegate。例如，在 Swift 3 中：
class TransitioningDelegate: NSObject, UIViewControllerTransitioningDelegate {
func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
return AnimationController(transitionType: .presenting)
}
func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
return AnimationController(transitionType: .dismissing)
}
}
如果在 Swift 3 中关闭，动画控制器会简单地执行 .transitionFlipFromRight 或 .transitionFlipFromLeft：
class AnimationController: NSObject, UIViewControllerAnimatedTransitioning {
enum TransitionType {
case presenting
case dismissing
}
var animationTransitionOptions: UIViewAnimationOptions
init(transitionType: TransitionType) {
switch transitionType {
case .presenting:
animationTransitionOptions = .transitionFlipFromRight
case .dismissing:
animationTransitionOptions = .transitionFlipFromLeft
}
super.init()
}
func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
//let inView = transitionContext.containerView
let toView = transitionContext.viewController(forKey: .to)?.view
let fromView = transitionContext.viewController(forKey: .from)?.view
UIView.transition(from: fromView!, to: toView!, duration: transitionDuration(using: transitionContext), options: animationTransitionOptions.union(.curveEaseInOut)) { finished in
transitionContext.completeTransition(true)
}
}
func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
return 1.0
}
}
有关 iOS 7 中引入的自定义过渡的更多信息，请参阅 WWDC 2013 视频Custom Transitions Using View Controllers。
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如果应该承认上面的AnimationController实际上是一个过度简化，因为我们使用的是transform(from:to:...)。这会导致动画无法取消（如果您使用的是交互式过渡）。它还删除了“来自”视图本身，从 iOS 8 开始，这实际上是演示控制器的工作。
所以，您真的很想使用UIView.animate API 来制作翻转动画。我很抱歉，因为以下涉及在关键帧动画中使用一些不直观的CATransform3D，但它会导致翻转动画，然后可以进行可取消的交互式过渡。
所以，在 Swift 3 中：
class AnimationController: NSObject, UIViewControllerAnimatedTransitioning {
enum TransitionType {
case presenting
case dismissing
}
let transitionType: TransitionType
init(transitionType: TransitionType) {
self.transitionType = transitionType
super.init()
}
func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
let inView = transitionContext.containerView
let toView = transitionContext.view(forKey: .to)!
let fromView = transitionContext.view(forKey: .from)!
var frame = inView.bounds
func flipTransform(angle: CGFloat, offset: CGFloat = 0) -> CATransform3D {
var transform = CATransform3DMakeTranslation(offset, 0, 0)
transform.m34 = -1.0 / 1600
transform = CATransform3DRotate(transform, angle, 0, 1, 0)
return transform
}
toView.frame = inView.bounds
toView.alpha = 0
let transformFromStart: CATransform3D
let transformFromEnd: CATransform3D
let transformFromMiddle: CATransform3D
let transformToStart: CATransform3D
let transformToMiddle: CATransform3D
let transformToEnd: CATransform3D
switch transitionType {
case .presenting:
transformFromStart = flipTransform(angle: 0, offset: inView.bounds.size.width / 2)
transformFromEnd = flipTransform(angle: -.pi, offset: inView.bounds.size.width / 2)
transformFromMiddle = flipTransform(angle: -.pi / 2)
transformToStart = flipTransform(angle: .pi, offset: -inView.bounds.size.width / 2)
transformToMiddle = flipTransform(angle: .pi / 2)
transformToEnd = flipTransform(angle: 0, offset: -inView.bounds.size.width / 2)
toView.layer.anchorPoint = CGPoint(x: 0, y: 0.5)
fromView.layer.anchorPoint = CGPoint(x: 1, y: 0.5)
case .dismissing:
transformFromStart = flipTransform(angle: 0, offset: -inView.bounds.size.width / 2)
transformFromEnd = flipTransform(angle: .pi, offset: -inView.bounds.size.width / 2)
transformFromMiddle = flipTransform(angle: .pi / 2)
transformToStart = flipTransform(angle: -.pi, offset: inView.bounds.size.width / 2)
transformToMiddle = flipTransform(angle: -.pi / 2)
transformToEnd = flipTransform(angle: 0, offset: inView.bounds.size.width / 2)
toView.layer.anchorPoint = CGPoint(x: 1, y: 0.5)
fromView.layer.anchorPoint = CGPoint(x: 0, y: 0.5)
}
toView.layer.transform = transformToStart
fromView.layer.transform = transformFromStart
inView.addSubview(toView)
UIView.animateKeyframes(withDuration: self.transitionDuration(using: transitionContext), delay: 0, options: [], animations: {
UIView.addKeyframe(withRelativeStartTime: 0, relativeDuration: 0.0) {
toView.alpha = 0
fromView.alpha = 1
}
UIView.addKeyframe(withRelativeStartTime: 0, relativeDuration: 0.5) {
toView.layer.transform = transformToMiddle
fromView.layer.transform = transformFromMiddle
}
UIView.addKeyframe(withRelativeStartTime: 0.5, relativeDuration: 0.0) {
toView.alpha = 1
fromView.alpha = 0
}
UIView.addKeyframe(withRelativeStartTime: 0.5, relativeDuration: 0.5) {
toView.layer.transform = transformToEnd
fromView.layer.transform = transformFromEnd
}
}, completion: { finished in
toView.layer.transform = CATransform3DIdentity
fromView.layer.transform = CATransform3DIdentity
toView.layer.anchorPoint = CGPoint(x: 0.5, y: 0.5)
fromView.layer.anchorPoint = CGPoint(x: 0.5, y: 0.5)
transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
})
}
func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
return 1.0
}
}
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仅供参考，iOS 8 使用演示控制器扩展了自定义过渡模型。更多信息，请参见 WWDC 2014 视频A Look Inside Presentation Controllers。
无论如何，如果在过渡结束时，“来自”视图不再可见，您会指示您的演示控制器将其从视图层次结构中删除，例如：
class PresentationController: UIPresentationController {
override var shouldRemovePresentersView: Bool { return true }
}
而且，很明显，你必须通知你的 TransitioningDelegate 这个演示控制器：
class TransitioningDelegate: NSObject, UIViewControllerTransitioningDelegate {
...
func presentationController(forPresented presented: UIViewController, presenting: UIViewController?, source: UIViewController) -> UIPresentationController? {
return PresentationController(presentedViewController: presented, presenting: presenting)
}
}