我把最終的Demo稍做修改，算是找了一個合適的應用場景，另外配上幾張美圖，拉拉人氣
。
雖然是Swift的Demo，但是轉成Objective-C相當容易。
最終效果預覽：
自定義導航欄的Push/Pop動畫
爲了在基於UINavigationController下做自定義的動畫切換，先建立一個簡單的工程，這個工程的rootViewController是一個UINavigationController，UINavigationController的rootViewController是一個簡單的UIViewController（稱之爲主頁面），通過這個UIViewController上的一個Button能進入到下一個UIViewController中（稱之爲詳情頁面），我們先在主頁面的ViewController上實現兩個協議：UINavigationControllerDelegate和UIViewControllerAnimatedTransitioning，然後在ViewDidLoad裏面把navigationController的delegate設爲self，這樣在導航欄Push和Pop的時候我們就知道了，然後用一個屬性記下是Push還是Pop，就像這樣：
func navigationController(navigationController: UINavigationController!, animationControllerForOperation operation: UINavigationControllerOperation, fromViewController fromVC: UIViewController!, toViewController toVC: UIViewController!) -> UIViewControllerAnimatedTransitioning! {
navigationOperation = operation
return self
}
這是iOS7的新方法，這個方法需要你提供一個UIViewControllerAnimatedTransitioning，那UIViewControllerAnimatedTransitioning到底是什麼呢？
UIViewControllerAnimatedTransitioning是蘋果新增加的一個協議，其目的是在需要使用自定義動畫的同時，又不影響視圖的其他屬性，讓你把焦點集中在動畫實現的本身上，然後通過在這個協議的回調裏編寫自定義的動畫代碼，即“切換中應該會發生什麼”，負責切換的具體內容，任何實現了這一協議的對象被稱之爲動畫控制器。你可以藉助協議能被任何對象實現的這一特性，從而把各種動畫效果封裝到不同的類中，只要方便使用和管理，你可以發揮一切手段。我在這裏讓主頁面實現動畫控制器也是可以的，因爲它是導航欄的rootViewController，會一直存在，我只要在裏面編寫自定義的Push和Pop動畫代碼就可以了：
//UIViewControllerTransitioningDelegate
func transitionDuration(transitionContext: UIViewControllerContextTransitioning!) -> NSTimeInterval {
return 0.4
}
func animateTransition(transitionContext: UIViewControllerContextTransitioning!) {
let containerView = transitionContext.containerView()
let toViewController = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey)
let fromViewController = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey)
var destView: UIView!
var destTransform: CGAffineTransform!
if navigationOperation == UINavigationControllerOperation.Push {
containerView.insertSubview(toViewController.view, aboveSubview: fromViewController.view)
destView = toViewController.view
destView.transform = CGAffineTransformMakeScale(0.1, 0.1)
destTransform = CGAffineTransformMakeScale(1, 1)
} else if navigationOperation == UINavigationControllerOperation.Pop {
containerView.insertSubview(toViewController.view, belowSubview: fromViewController.view)
destView = fromViewController.view
// 如果IDE是Xcode6 Beta4+iOS8SDK，那麼在此處設置爲0，動畫將不會被執行(不確定是哪裏的Bug)
destTransform = CGAffineTransformMakeScale(0.1, 0.1)
}
UIView.animateWithDuration(transitionDuration(transitionContext), animations: {
destView.transform = destTransform
}, completion: ({completed in
transitionContext.completeTransition(true)
}))
}
上面第一個方法返回動畫持續的時間，而下面這個方法纔是具體需要實現動畫的地方。UIViewControllerAnimatedTransitioning的協議都包含一個對象：transitionContext，通過這個對象能獲取到切換時的上下文信息，比如從哪個VC切換到哪個VC等。我們從transitionContext獲取containerView，這是一個特殊的容器，切換時的動畫將在這個容器中進行；UITransitionContextFromViewControllerKey和UITransitionContextToViewControllerKey就是從哪個VC切換到哪個VC，容易理解；除此之外，還有直接獲取view的UITransitionContextFromViewKey和UITransitionContextToViewKey等。
我按Push和Pop把動畫簡單的區分了一下，Push時scale由小變大，Pop時scale由大變小，不同的操作，toViewController的視圖層次也不一樣。最後，在動畫完成的時候調用completeTransition，告訴transitionContext你的動畫已經結束，這是非常重要的方法，必須調用。在動畫結束時沒有對containerView的子視圖進行清理（比如把fromViewController的view移除掉）是因爲transitionContext會自動清理，所以我們無須在額外處理。
注意一點，這樣一來會發現原來導航欄的交互式返回效果沒有了，如果你想用原來的交互式返回效果的話，在返回動畫控制器的delegate方法裏返回nil，如：
if operation == UINavigationControllerOperation.Push {
navigationOperation = operation
return self
}
return nil
一個簡單的自定義導航欄Push/Pop動畫就完成了。
自定義Modal的Present/Dismiss動畫
func transitionDuration(transitionContext: UIViewControllerContextTransitioning!) -> NSTimeInterval {
return 0.6
}
func animateTransition(transitionContext: UIViewControllerContextTransitioning!) {
let containerView = transitionContext.containerView()
let toViewController = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey)
let fromViewController = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey)
var destView: UIView!
var destTransfrom = CGAffineTransformIdentity
let screenHeight = UIScreen.mainScreen().bounds.size.height
if modalPresentingType == ModalPresentingType.Present {
destView = toViewController.view
destView.transform = CGAffineTransformMakeTranslation(0, screenHeight)
containerView.addSubview(toViewController.view)
} else if modalPresentingType == ModalPresentingType.Dismiss {
destView = fromViewController.view
destTransfrom = CGAffineTransformMakeTranslation(0, screenHeight)
containerView.insertSubview(toViewController.view, belowSubview: fromViewController.view)
}
UIView.animateWithDuration(transitionDuration(transitionContext), delay: 0, usingSpringWithDamping: 0.6, initialSpringVelocity: 0,
options: UIViewAnimationOptions.CurveLinear, animations: {
destView.transform = destTransfrom
}, completion: {completed in
transitionContext.completeTransition(true)
})
}
func animationControllerForPresentedController(presented: UIViewController!, presentingController presenting: UIViewController!, sourceController source: UIViewController!) -> UIViewControllerAnimatedTransitioning! {
modalPresentingType = ModalPresentingType.Present
return self
}
func animationControllerForDismissedController(dismissed: UIViewController!) -> UIViewControllerAnimatedTransitioning! {
modalPresentingType = ModalPresentingType.Dismiss
return self
}
override func prepareForSegue(segue: UIStoryboardSegue!, sender: AnyObject!) {
let modal = segue.destinationViewController as UIViewController
modal.transitioningDelegate = self
}
自定義導航欄的交互式動畫
使用UIPercentDrivenInteractiveTransition
實際上這個類就是實現了UIViewControllerInteractiveTransitioning協議的交互控制器，我們使用它就能夠輕鬆地爲動畫控制器添加一個交互動畫。調用updateInteractiveTransition:更新進度；調用cancelInteractiveTransition取消交互，返回到切換前的狀態；調用finishInteractiveTransition通知上下文交互已完成，同completeTransition一樣。我們把交互動畫應用到詳情頁面Back回主頁面的地方，由於之前的動畫管理器的角色是主頁面擔任的，Navigation Controller的delegate同一時間只能有一個，那在這裏交互控制器的角色也由主頁面來擔任。首先添加一個手勢識別器：
let popRecognizer = UIScreenEdgePanGestureRecognizer(target: self, action: Selector("handlePopRecognizer:"))
popRecognizer.edges = UIRectEdge.Left
self.navigationController.view.addGestureRecognizer(popRecognizer)
func handlePopRecognizer(popRecognizer: UIScreenEdgePanGestureRecognizer) {
var progress = popRecognizer.translationInView(navigationController.view).x / navigationController.view.bounds.size.width
progress = min(1.0, max(0.0, progress))
println("\(progress)")
if popRecognizer.state == UIGestureRecognizerState.Began {
println("Began")
self.interactivePopTransition = UIPercentDrivenInteractiveTransition()
self.navigationController.popViewControllerAnimated(true)
} else if popRecognizer.state == UIGestureRecognizerState.Changed {
self.interactivePopTransition?.updateInteractiveTransition(progress)
println("Changed")
} else if popRecognizer.state == UIGestureRecognizerState.Ended || popRecognizer.state == UIGestureRecognizerState.Cancelled {
if progress > 0.5 {
self.interactivePopTransition?.finishInteractiveTransition()
} else {
self.interactivePopTransition?.cancelInteractiveTransition()
}
println("Ended || Cancelled")
self.interactivePopTransition = nil
}
}
現在我們已經有了交互控制器對象，只需要把它給告知給Navigation Controller就行了，我們實現UINavigationControllerDelegate的另一個方法：
func navigationController(navigationController: UINavigationController!, interactionControllerForAnimationController animationController: UIViewControllerAnimatedTransitioning!) -> UIViewControllerInteractiveTransitioning! {
return self.interactivePopTransition
}
我們從詳情頁面通過自定義的交互動畫返回到上一個頁面的工作就完成了。
Demo效果預覽：
使用UIPercentDrivenInteractiveTransition的Demo
自定義交互控制器
func startInteractiveTransition(transitionContext: UIViewControllerContextTransitioning!) {
self.transitionContext = transitionContext
let containerView = transitionContext.containerView()
let toViewController = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey)
let fromViewController = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey)
containerView.insertSubview(toViewController.view, belowSubview: fromViewController.view)
self.transitingView = fromViewController.view
}
func updateWithPercent(percent: CGFloat) {
let scale = CGFloat(fabsf(Float(percent - CGFloat(1.0))))
transitingView?.transform = CGAffineTransformMakeScale(scale, scale)
transitionContext?.updateInteractiveTransition(percent)
}
func finishBy(cancelled: Bool) {
if cancelled {
UIView.animateWithDuration(0.4, animations: {
self.transitingView!.transform = CGAffineTransformIdentity
}, completion: {completed in
self.transitionContext!.cancelInteractiveTransition()
self.transitionContext!.completeTransition(false)
})
} else {
UIView.animateWithDuration(0.4, animations: {
print(self.transitingView)
self.transitingView!.transform = CGAffineTransformMakeScale(0, 0)
print(self.transitingView)
}, completion: {completed in
self.transitionContext!.finishInteractiveTransition()
self.transitionContext!.completeTransition(true)
})
}
}
func handlePopRecognizer(popRecognizer: UIScreenEdgePanGestureRecognizer) {
var progress = popRecognizer.translationInView(navigationController.view).x / navigationController.view.bounds.size.width
progress = min(1.0, max(0.0, progress))
println("\(progress)")
if popRecognizer.state == UIGestureRecognizerState.Began {
println("Began")
isTransiting = true
//self.interactivePopTransition = UIPercentDrivenInteractiveTransition()
self.navigationController.popViewControllerAnimated(true)
} else if popRecognizer.state == UIGestureRecognizerState.Changed {
//self.interactivePopTransition?.updateInteractiveTransition(progress)
updateWithPercent(progress)
println("Changed")
} else if popRecognizer.state == UIGestureRecognizerState.Ended || popRecognizer.state == UIGestureRecognizerState.Cancelled {
//if progress > 0.5 {
// self.interactivePopTransition?.finishInteractiveTransition()
//} else {
// self.interactivePopTransition?.cancelInteractiveTransition()
//}
finishBy(progress < 0.5)
println("Ended || Cancelled")
isTransiting = false
//self.interactivePopTransition = nil
}
}
func navigationController(navigationController: UINavigationController!, interactionControllerForAnimationController animationController:
UIViewControllerAnimatedTransitioning!) -> UIViewControllerInteractiveTransitioning! {
if !self.isTransiting {
return nil
}
return self
}
最終效果:
@availability(iOS, introduced=7.0)
func snapshotViewAfterScreenUpdates(afterUpdates: Bool) -> UIView
最後附上一張圖，這個圖比較容易區分那幾個名稱相近的協議：
UPDATED:
原文轉之：http://blog.csdn.net/zhangao0086/article/details/38459937