iOS9中將轉場動畫和ViewController剝離,可以自定義Segue,從而復用.
Segues默認有幾種方式:

• Show: 從Navigation Controller push一個頁面.
• Show Detail: 向上彈出一個新的頁面.
• Present Modally: 在當前頁面覆蓋一個新的頁面.
• Popover: iPad彈出個小界面iPhone全屏以Model形式彈出一個界面.
• Custom:自定義Segue
  關于不同Segue的區別和用法可以參考這里 那里和最后這篇
  iOS8中已經不建議使用以前Segue的Push Modal Popover和Replace了.
  我們要來創建一個如下圖的轉場效果:

ScaleTransition.png

Segue有三個重要的協議:

• UIViewControllerTransitioningDelegate
• UIViewControllerAnimatedTransitioning
• UIViewControllerContextTransitioning
  我們創建一個ScaleSegue文件:

class ScaleSegue: UIStoryboardSegue {
  
  override func perform() {
    destinationViewController.transitioningDelegate = self
    super.perform()
  }
}

定義轉場動畫:

extension ScaleSegue: UIViewControllerTransitioningDelegate {
  func animationControllerForPresentedController(presented: UIViewController,
     presentingController presenting: UIViewController,
     sourceController source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
    return ScalePresentAnimator()
  }
}

class ScalePresentAnimator: NSObject, UIViewControllerAnimatedTransitioning {
  func transitionDuration(transitionContext: UIViewControllerContextTransitioning?) -> NSTimeInterval {
    return 2.0
  }
  
  func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
    var fromViewController = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey)!
    if let fromNC = fromViewController as? UINavigationController {
      if let controller = fromNC.topViewController {
        fromViewController = controller
      }
    }
    let fromView = transitionContext.viewForKey(UITransitionContextFromViewKey)
    
    let toViewController = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey)!
    let toView = transitionContext.viewForKey(UITransitionContextToViewKey)

    if let toView = toView {
      transitionContext.containerView()?.addSubview(toView)
    }
    
    var startFrame = CGRect.zero
    if let fromViewController = fromViewController as? ViewScaleable {
      startFrame = fromViewController.scaleView.frame
    } else {
      print("Warning: Controller \(fromViewController) does not conform to ViewScaleable")
    }
    toView?.frame = startFrame
    toView?.layoutIfNeeded()
    
    let duration = transitionDuration(transitionContext)
    let finalFrame = transitionContext.finalFrameForViewController(toViewController)
    
    UIView.animateWithDuration(duration, animations: {
      toView?.frame = finalFrame
      toView?.layoutIfNeeded()
      fromView?.alpha = 0.0
      }, completion: {
        finished in
        fromView?.alpha = 1.0
        transitionContext.completeTransition(true)
    })
  }

最后設置下Segue class:

segueclass.png