How to use UIViewControllerAnimatedTransitioning w

问题:

How can I get custom transitions (iOS7) when pushing a view controller onto UINavigationController? I tried setting the TransitioningDelegate both in the UINavigationController and also on the controller I'm pushing The methods never get called.

All examples I find use custom transitions when presenting modally.

回答1:

@rounak has the right idea, but sometimes it helps to have code ready without having to download from github.

Here are the steps that I took:

1. Make your FromViewController.m conform to UINavigationControllerDelegate. Other sample code out there tells you to conform to UIViewControllerTransitioningDelegate, but that's only if you're presenting the ToViewController.

   @interface ViewController : UIViewController

2. Return your custom transition animator object in the delegate callback method in FromViewController:

   - (id <UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController
                                  animationControllerForOperation:(UINavigationControllerOperation)operation
                                               fromViewController:(UIViewController *)fromVC
                                                 toViewController:(UIViewController *)toVC {
       TransitionAnimator *animator = [TransitionAnimator new];
       animator.presenting = (operation == UINavigationControllerOperationPush);
       return animator;
   }
   

3. Create your custom animator class and paste these sample methods:

   - (NSTimeInterval)transitionDuration:(id <UIViewControllerContextTransitioning>)transitionContext {
       return 0.5f;
       }
   
   - (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext     {
   // Grab the from and to view controllers from the context
   UIViewController *fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
   UIViewController *toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
   
   // Set our ending frame. We'll modify this later if we have to
   CGRect endFrame = CGRectMake(80, 280, 160, 100);
   
   if (self.presenting) {
       fromViewController.view.userInteractionEnabled = NO;
   
       [transitionContext.containerView addSubview:fromViewController.view];
       [transitionContext.containerView addSubview:toViewController.view];
   
       CGRect startFrame = endFrame;
       startFrame.origin.x += 320;
   
       toViewController.view.frame = startFrame;
   
       [UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^{
           fromViewController.view.tintAdjustmentMode = UIViewTintAdjustmentModeDimmed;
           toViewController.view.frame = endFrame;
       } completion:^(BOOL finished) {
           [transitionContext completeTransition:YES];
       }];
   }
   else {
       toViewController.view.userInteractionEnabled = YES;
   
       [transitionContext.containerView addSubview:toViewController.view];
       [transitionContext.containerView addSubview:fromViewController.view];
   
       endFrame.origin.x += 320;
   
       [UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^{
           toViewController.view.tintAdjustmentMode = UIViewTintAdjustmentModeAutomatic;
           fromViewController.view.frame = endFrame;
       } completion:^(BOOL finished) {
           [transitionContext completeTransition:YES];
       }];
   }
   }
   

Essentially, the animator is the object doing the heavy lifting. Of course, you can make your UINavigationControllerDelegate be a separate object, but that depends on how your architect your app.

回答2:

objc.io's post on view controller transitions are specifically for pushing and popping view controllers. http://objc.io/issue-5/view-controller-transitions.html

I've done this animation (http://i.imgur.com/1qEyMu3.gif) solely based on the objc.io post.

In short you have to have a class(es) implementing UINavigationControllerDelegate, and UIViewControllerAnimatedTransitioning with the required methods for returning the correct animator, and performing the animations.

回答3:

You can look at my demo project which demonstrates using custom transitions in UINavigationController. Look at https://github.com/Vaberer/BlurTransition.

回答4:

EDIT: Just realised this might not answer your question. But it is an alternative.

If you're using a storyboard you can do a custom transition by creating a custom segue. In the attributes inspector change the segue class name to your custom transition class e.g. MySegue. Then create the MySegue class and implement the -(void)perform method to perform your transition.

- (void) perform{
      UIViewController *source = self.sourceViewController;
      UIViewController *destination = self.destinationViewController;
      [UIView transitionFromView:source.view
                          toView:destination.view
                        duration:0.50f
                         options:UIViewAnimationOptionTransitionFlipFromTop
                      completion:nil];
}