前言: 自定義轉場動畫其實並不難, 關鍵在於能夠明白思路, 也就是操作步驟. 本篇博客主要以present轉場動畫為例, 進行分析, 操作, 如有錯誤歡迎簡信與我交流.

不進行修改的話, presentViewController:animated:completion:相信這個方法很多人都是用過, 稱作模態推出界面, 默認都是從屏幕下方推出新的控制器.
自定義的目的就是為了修改固定的推出方式, 同時加上你想要的動畫.

一個關鍵的概念: UIViewControllerAnimatedTransitioning控制動畫的協議, 需要自己實現這個. 下面來一看看代碼如何進行實現.

 

@interface ViewController ()

跳轉點擊方法

- (void)click:(UIButton *)sender
{
  ModelViewController *modalViewController = [ModelViewController new];
    // 指定代理
  modalViewController.transitioningDelegate = self;
    // Style = 自定義方式
  modalViewController.modalPresentationStyle = UIModalPresentationCustom;
  [self presentViewController:modalViewController
                      animated:YES
                     completion:NULL];
}

UIViewControllerTransitioningDelegate

// 修改動畫的兩個相關的協議方法, 建議仔細查看UIViewControllerTransitioningDelegate裡面的注釋
-(id)animationControllerForPresentedController:(UIViewController *)presented
                                 presentingController:(UIViewController *)presenting
                                   sourceController:(UIViewController *)source
{
    // 推出動畫 - 下面會給出代碼 我參照POP動畫Demo寫的.
  return [PresentAnimator new];
}

- (id)animationControllerForDismissedController:(UIViewController *)dismissed
{
    // 退出 
  return [DismissAnimator new];
}
// 想要實現手勢控制可在這個方法中進行修改
-(id)interactionControllerForDismissal:(id)animator {

}

關鍵在於動畫如何實現 分別進行的實現PresentAnimator, DismissAnimator的實現.

UIViewControllerAnimatedTransitioning使用這個協議進行修改.

@interface PresentAnimator : NSObject 

PresentAnimator.m

// 交互所用時間
- (NSTimeInterval)transitionDuration:(id )transitionContext
{
  return 0.5f;
}
// 具體動畫方式, 上面提到的POP
- (void)animateTransition:(id )transitionContext
{
    // 這裡拿到即將新推出的VC的View
  UIView *toView = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey].view;
    // 這裡設置退出view具體如何設置
  toView.frame = CGRectMake(0,0, SCREEN_WIDTH, SCREEN_HEIGHT);
  toView.center = CGPointMake(transitionContext.containerView.center.x, -transitionContext.containerView.center.y);
 
  [transitionContext.containerView addSubview:toView];
    // pop動畫 
  POPSpringAnimation *positionAnim = [POPSpringAnimation animationWithPropertyNamed:kPOPLayerPositionY];
  positionAnim.toValue = @(transitionContext.containerView.center.y);
  positionAnim.springBounciness = 10;
  [positionAnim setCompletionBlock:^(POPAnimation *anim, BOOL finished) {
    [transitionContext completeTransition:YES];
  }];
  POPSpringAnimation *scaleAnim = [POPSpringAnimation animationWithPropertyNamed:kPOPLayerScaleXY];
  scaleAnim.springBounciness = 20;
  scaleAnim.fromValue = [NSValue valueWithCGPoint:CGPointMake(1.2, 1.4)];
 
  [toView.layer pop_addAnimation:positionAnim forKey:@"positionAnimation"];
  [toView.layer pop_addAnimation:scaleAnim forKey:@"scaleAnimation"];
}

DismissAnimator.m

- (NSTimeInterval)transitionDuration:(id )transitionContext
{
  return 0.5f;
}

- (void)animateTransition:(id )transitionContext
{
    // fromVC 很好理解吧?? 就是從哪個控制器推過來回到哪裡去.
  UIViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
  POPBasicAnimation *offscreenAnimation = [POPBasicAnimation animationWithPropertyNamed:kPOPLayerPositionY];
  offscreenAnimation.toValue = @(-fromVC.view.layer.position.y);
  [offscreenAnimation setCompletionBlock:^(POPAnimation *anim, BOOL finished) {
    [transitionContext completeTransition:YES];
  }];
  [fromVC.view.layer pop_addAnimation:offscreenAnimation forKey:@"offscreenAnimation"];
}

順便值得一提的是UINavigationController轉場的動畫也是可以自定義的. 通過這個
UINavigationControllerDelegate來完成

    // 簽訂這個協議
  self.navigationController.delegate = self;

- (id) navigationController:(UINavigationController *)navigationController animationControllerForOperation:(UINavigationControllerOperation)operation fromViewController:(UIViewController *)fromVC toViewController:(UIViewController *)toVC
{
 
  if (operation == UINavigationControllerOperationPush) {
        // 動畫的方式不變
    return [PresentAnimator new];
  }else{
    return nil;
  }
}