参照：iOS 自定义页面的切换动画与交互动画 By Swift
oc 版切换动画
一、自定义导航栏的Push/Pop动画
为了在基于UINavigationController下做自定义的动画切换，
1、先建立一个简单的工程，建一个UINavigationController的子类LSNavigationController，另外两个VC viewController和secondViewController，注意：viewController是一个UINavigationController。在这两个页面中先做一些准备工作就是各有一个按钮，一个做push操作，一个做pop操作。
2、LSNavigationController ，用来实现UINavigationControllerDelegate```协议。在类中实现代理函数
func navigationController(_ navigationController: UINavigationController, animationControllerFor operation: UINavigationControllerOperation, from fromVC: UIViewController, to toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? {
if operation == UINavigationControllerOperation.push {
return LSPushAnimation.init()
}else if operation == UINavigationControllerOperation.pop {
return LSPopAnimation.init()
}
return nil
}
上面的协议函数会在push和pop时返回已经实现了动画方法的类LSPushAnimation和LSPopAnimation。
在viewController的viewDidLoad中self.navigationController?.delegate = self，因为导航器的第一个页面一直存在，所以只需要在这里设置就可。
3、编写动画类，由于pop和push实现方式类似，只拿push为例：
在LSPushAnimation中实现UIViewControllerAnimatedTransitioning协议。 UIViewControllerAnimatedTransitioning是苹果新增加的一个协议，其目的是在需要使用自定义动画的同时，又不影响视图的其他属性，让你把焦点集中在动画实现的本身上，然后通过在这个协议的回调里编写自定义的动画代码，即“切换中应该会发生什么”，负责切换的具体内容，任何实现了这一协议的对象被称之为动画控制器。
实现两个协议函数
//UIViewControllerAnimatedTransitioning
func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
return 0.4
}
func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
let containerView = transitionContext.containerView
let toViewController = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.to)
let fromViewController = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.from)
var destView: UIView!
var destTransform: CGAffineTransform!
containerView.insertSubview((toViewController?.view)!, aboveSubview: (fromViewController?.view)!)
destView = toViewController?.view
destView.transform = CGAffineTransform(scaleX: 0.1, y: 0.1)
destTransform = CGAffineTransform(scaleX: 1, y: 1)
UIView.animate(withDuration: transitionDuration(using: transitionContext), animations: {
destView.transform = destTransform
}, completion: ({completed in
transitionContext.completeTransition(true)
}))
}
上面第一个方法返回动画持续的时间，而下面这个方法才是具体需要实现动画的地方。UIViewControllerAnimatedTransitioning的协议都包含一个对象：transitionContext，通过这个对象能获取到切换时的上下文信息，比如从哪个VC切换到哪个VC等。我们从transitionContext获取containerView，这是一个特殊的容器，切换时的动画将在这个容器中进行；UITransitionContextFromViewControllerKey和UITransitionContextToViewControllerKey就是从哪个VC切换到哪个VC，容易理解；除此之外，还有直接获取view的UITransitionContextFromViewKey和UITransitionContextToViewKey等。
我按Push和Pop把动画简单的区分了一下，Push时scale由小变大，Pop时scale由大变小，不同的操作，toViewController的视图层次也不一样。最后，在动画完成的时候调用completeTransition，告诉transitionContext你的动画已经结束，这是非常重要的方法，必须调用。在动画结束时没有对containerView的子视图进行清理（比如把fromViewController的view移除掉）是因为transitionContext会自动清理，所以我们无须在额外处理。
4、这样，只需在
注意一点，这样一来会发现原来导航栏的交互式返回效果没有了，如果你想用原来的交互式返回效果的话，在返回动画控制器的delegate方法里返回nil，如：
if operation == UINavigationControllerOperation.Push {
navigationOperation = operation
return self
}
return nil
然后在LSNavigationController的viewDidLoad里，Objective-C直接self.navigationController.interactivePopGestureRecognizer.delegat ＝ self就行了，Swift除了要navigationController.interactivePopGestureRecognizer.delegate = self之外，还要在self上声明实现了UIGestureRecognizerDelegate这个协议，虽然实际上你并没有实现。
一个简单的自定义导航栏Push/Pop动画就完成了。
二、自定义Modal的Present/Dismiss动画
自定义Modal的Present与Dismiss动画与之前类似，都需要提供一个动画管理器，我们用详情页面来展示一个Modal页面，详情页面就作为动画管理器：
为了方便，我依然在LSViewController操作(实际开发中，只需要在有特殊需要的页面中实现即可)，
1、 LSViewController实现协议UIViewControllerTransitioningDelegate,这个协议与之前的UINavigationControllerDelegate协议具有相似性，都是返回一个动画管理器，
func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
return LSPresentAnimation.init()
}
func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
return LSDismissAnimation.init()
}
其中LSPresentAnimation和LSDismissAnimation也是实现了UIViewControllerAnimatedTransitioning协议的用来实现具体的动画。直接上代码。
//UIViewControllerAnimatedTransitioning
func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
return 0.6
}
func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
let containerView = transitionContext.containerView
let toViewController = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.to)
let fromViewController = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.from)
var destView: UIView!
var destTransfrom = CGAffineTransform()
let screenHeight = UIScreen.main
.bounds.size.height
destView = toViewController?.view
destView.transform = CGAffineTransform(translationX: 0, y: screenHeight)
containerView.addSubview((toViewController?.view)!)
UIView.animate(withDuration: transitionDuration(using: transitionContext), delay: 0, usingSpringWithDamping: 0.6, initialSpringVelocity: 0,
options: UIViewAnimationOptions.curveLinear, animations: {
destView.transform = destTransfrom
}, completion: {completed in
transitionContext.completeTransition(true)
})
}
3、在 LSViewController中self.transitioningDelegate = self(之所以让viewController和secondViewcontroller继承LSViewController是因为懒，都写在一起了，不然需要在两个VC中实现)
这样present就会有动画，想要dismiss也实现我们自己的动画需要在viewControllerpresent按钮中将 secondViewController定位动画管理器。
三、自定义导航栏的交互式动画
与动画控制器类似，我们把实现了*** UIViewControllerInteractiveTransitioning 协议的对象称之为交互控制器***，最常用的就是把交互控制器应用到导航栏的Back手势返回上，而如果要实现一个自定义的交互式动画，我们有两种方式来完成：实现一个交互控制器，或者使用iOS提供的UIPercentDrivenInteractiveTransition类作交互控制器。
使用
UIPercentDrivenInteractiveTransition
我们这里就用UIPercentDrivenInteractiveTransition来完成导航栏的交互式动画。先看下UIPercentDrivenInteractiveTransition的定义：
open class UIPercentDrivenInteractiveTransition : NSObject, UIViewControllerInteractiveTransitioning {
/// This is the non-interactive duration that was returned when the
/// animators transitionDuration: method was called when the transition started.
open var duration: CGFloat { get }
/// The last percentComplete value specified by updateInteractiveTransition:
open var percentComplete: CGFloat { get }
/// completionSpeed defaults to 1.0 which corresponds to a completion duration of
/// (1 - percentComplete)*duration. It must be greater than 0.0. The actual
/// completion is inversely proportional to the completionSpeed. This can be set
/// before cancelInteractiveTransition or finishInteractiveTransition is called
/// in order to speed up or slow down the non interactive part of the
/// transition.
open var completionSpeed: CGFloat
/// When the interactive part of the transition has completed, this property can
/// be set to indicate a different animation curve. It defaults to UIViewAnimationCurveEaseInOut.
/// Note that during the interactive portion of the animation the timing curve is linear.
open var completionCurve: UIViewAnimationCurve
/// For an interruptible animator, one can specify a different timing curve provider to use when the
/// transition is continued. This property is ignored if the animated transitioning object does not
/// vend an interruptible animator.
@available(iOS 10.0, *)
open var timingCurve: UITimingCurveProvider?
/// Set this to NO in order to start an interruptible transition non
/// interactively. By default this is YES, which is consistent with the behavior
/// before 10.0.
@available(iOS 10.0, *)
open var wantsInteractiveStart: Bool
/// Use this method to pause a running interruptible animator. This will ensure that all blocks
/// provided by a transition coordinator's notifyWhenInteractionChangesUsingBlock: method
/// are executed when a transition moves in and out of an interactive mode.
@available(iOS 10.0, *)
open func pause()
// These methods should be called by the gesture recognizer or some other logic
// to drive the interaction. This style of interaction controller should only be
// used with an animator that implements a CA style transition in the animator's
// animateTransition: method. If this type of interaction controller is
// specified, the animateTransition: method must ensure to call the
// UIViewControllerTransitionParameters completeTransition: method. The other
// interactive methods on UIViewControllerContextTransitioning should NOT be
// called. If there is an interruptible animator, these methods will either scrub or continue
// the transition in the forward or reverse directions.
open func update(_ percentComplete: CGFloat)
open func cancel()
open func finish()
}
实际上这个类就是实现了UIViewControllerInteractiveTransitioning协议的交互控制器，我们使用它就能够轻松地为动画控制器添加一个交互动画。调用update更新进度；调用cancel取消交互，返回到切换前的状态；调用finish通知上下文交互已完成，同completeTransition一样。我们把交互动画应用到详情页面Back回主页面的地方，由于之前的动画管理器的角色是主页面担任的，Navigation Controller的delegate同一时间只能有一个。
首先我们需要创建一个交互控制器。新建一个Cocoa Touch Class文件，命名为LSPercentDrivenInteractiveTransition，让它继承自UIPercentDrivenInteractiveTransition。
打开LSNavigationController.swift，在类定义的最开始添加下面这些属性：
var interactionInProgress = false //用于指示交互是否在进行中。
///交互控制器
private var interactivePopTransition : LSPercentDrivenInteractiveTransition!
在viewDidLoad：中添加
self.delegate = self
let gesture = UIScreenEdgePanGestureRecognizer(target:self,action:#selector(handleGesture(gestureRecognizer:)))
gesture.edges = .left
self.view.addGestureRecognizer(gesture)
并实现手势的方法：
// 以下----使用UIPercentDrivenInteractiveTransition交互控制器
func handleGesture(gestureRecognizer: UIScreenEdgePanGestureRecognizer) {
var progress = gestureRecognizer.translation(in: gestureRecognizer.view?.superview).x / self.view.bounds.size.width
progress = min(1.0, max(0.0, progress))
// let translation = gestureRecognizer.translation(in: gestureRecognizer.view?.superview)
// var progress = Float(translation.x / 200)
// progress = fminf(fmaxf(progress, 0.0), 1.0)
print("\(progress)")
if gestureRecognizer.state == UIGestureRecognizerState.began {
print("Began")
self.interactivePopTransition = LSPercentDrivenInteractiveTransition()
interactionInProgress = true
self.popViewController(animated: true)
} else if gestureRecognizer.state == UIGestureRecognizerState.changed {
self.interactivePopTransition.update(CGFloat(progress))
print("Changed")
} else if gestureRecognizer.state == UIGestureRecognizerState.ended || gestureRecognizer.state == UIGestureRecognizerState.cancelled {
if progress > 0.5 {
self.interactivePopTransition.finish()
print("finished")
} else {
self.interactivePopTransition.cancel()
print("canceled")
}
interactionInProgress = false
self.interactivePopTransition = nil
}
}
- 手势开始后，我们初始化交互控制器self.interactivePopTransition，调整interactionInProgress的值并触发关闭视图控制器的操作。
- 手势进行时，我们不断调用update方法更新进度。它是UIPercentDrivenInteractiveTransition的一个方法，根据你传入的百分比值更新过渡动画。
- 如果手势被取消，更新interactionInProgress的值，并回滚过渡动画。
- 手势完成后，根据当前进度判断是取消还是完成过渡动画。
在LSNavigationController中实现UINavigationControllerDelegate协议，
/// UINavigationControllerDelegate 以下两个协议均实现时，以第二个为准，
func navigationController(_ navigationController: UINavigationController, animationControllerFor operation: UINavigationControllerOperation, from fromVC: UIViewController, to toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? {
if operation == UINavigationControllerOperation.push {
return LSPushAnimation.init()
}else if operation == UINavigationControllerOperation.pop {
return LSPopAnimation.init()
}
return nil
}
/// 当返回值为nil时，上面的协议返回的push和pop动画才会有作用
func navigationController(_ navigationController: UINavigationController, interactionControllerFor animationController: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning? {
if interactivePopTransition != nil {
return interactivePopTransition
}
return nil
}
这里的第一个方法前面已经用过，第二个是返回交互控制器，因为如果交互控制器不为空的话，就会调用控制器来控制交互，这样就使上面的push和pop失去的效果，所以只有在需要自定义交互控制器时才会返回，不然则返回nil即可（就像自定义滑动返回手势）。所以在上面的手势处理中才会在开始时初始化控制器，在结束后制为nil。
使用UIPercentDrivenInteractiveTransition的Demo
自定义交互控制器
在上面的demo基础上修改。
LSPercentDrivenInteractiveTransition需要自己实现UIViewControllerInteractiveTransitioning协议。
UIViewControllerInteractiveTransitioning协议总共有三个方法，其中startInteractiveTransition:是必须实现的方法，我们在里面初始化动画的状态：
///以下是自定义交互控制器
///先初始化需要的变量
var transitionContext : UIViewControllerContextTransitioning!
var transitingView : UIView!
/// 以下----自定义交互控制器
override func startInteractiveTransition(_ transitionContext: UIViewControllerContextTransitioning) {
self.transitionContext = transitionContext
let containerView = transitionContext.containerView
let toViewController = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.to)
let fromViewController = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.from)
containerView.insertSubview((toViewController?.view)!, belowSubview: (fromViewController?.view)!)
self.transitingView = fromViewController?.view
}
override func update(_ percentComplete: CGFloat) {
let scale = CGFloat(fabsf(Float(percentComplete - CGFloat(1.0))))
transitingView?.transform = CGAffineTransform(scaleX: scale, y: scale)
transitionContext?.updateInteractiveTransition(percentComplete)
}
func finishBy(cancelled: Bool) {
if cancelled {
UIView.animate(withDuration: 0.4, animations: {
self.transitingView!.transform = CGAffineTransform(scaleX: 1, y: 1)
}, completion: {completed in
self.transitionContext!.cancelInteractiveTransition()
self.transitionContext!.completeTransition(false)
})
} else {
UIView.animate(withDuration: 0.4, animations: {
print(self.transitingView)
self.transitingView!.transform = CGAffineTransform(scaleX: 0.1, y: 0.1)
print(self.transitingView)
}, completion: {completed in
self.transitionContext!.finishInteractiveTransition()
self.transitionContext!.completeTransition(true)
})
}
}
update:方法用来更新view的transform属性，finishBy:方法主要用来判断是进入下一个页面还是返回到之前的页面，并告知transitionContext目前的状态，以及对当前正在scale的view做最后的动画。这里的transitionContext和transitingView可以在前面的处理手势识别代码中取得，因此手势的处理中变成了：
///以下是自定义交互器
func handleGesture(gestureRecognizer: UIScreenEdgePanGestureRecognizer) {
var progress = gestureRecognizer.translation(in: gestureRecognizer.view?.superview).x / self.view.bounds.size.width
progress = min(1.0, max(0.0, progress))
// let translation = gestureRecognizer.translation(in: gestureRecognizer.view?.superview)
// var progress = Float(translation.x / 200)
// progress = fminf(fmaxf(progress, 0.0), 1.0)
print("\(progress)")
if gestureRecognizer.state == UIGestureRecognizerState.began {
print("Began")
self.interactivePopTransition = LSPercentDrivenInteractiveTransition()
interactionInProgress = true
self.popViewController(animated: true)
} else if gestureRecognizer.state == UIGestureRecognizerState.changed {
interactivePopTransition.update(progress)
print("Changed")
} else if gestureRecognizer.state == UIGestureRecognizerState.ended || gestureRecognizer.state == UIGestureRecognizerState.cancelled {
interactivePopTransition.finishBy(cancelled: progress < 0.5)
interactionInProgress = false
self.interactivePopTransition = nil
}
}
这样就完成了自定义交互控制器的全部内容。
注意，视图控制器的这些同样适用于model视图的动画（连接中包括三个工程，其中一个是图片浏览，swift代码还不太熟悉，需要改善）。
