Custom UIViewTransition Example

gistfile1.m

- (void)transitionFromViewController:(UIViewController *)fromViewController 
                    toViewController:(UIViewController *)toViewController 
                   withAnimationType:(EPBUIViewAnimationTransition)animation 
                      fromFrame:(CGRect)aFrame
                    withOverLayImage:(NSString *)overlayName {
  
  static NSInteger standardImageTag = 9999;
  
  if (fromViewController == toViewController) {
		return;
  }

  /**
   * Need to take in account the navbar
   */
	
  toViewController.view.frame = CGRectOffset(self.view.frame, 0, kTopViewOffset);

  self.selectedViewController = toViewController;
  
	/**
   * notify fromViewController
   */

	[fromViewController willMoveToParentViewController:nil];
  
	[self addChildViewController:toViewController];

  /**
   * Static completion animation block for inital anitmation
   *
   * Standard animation block that starts transition
   */

  void (^vt_animation_block)(void)                       = ^(void){};

  /**
   * Animation block is triggered once the inital animation has 
   * completed.
   */

  void (^vt_completion_animation_block)(void)            = ^(void){};

  /**
   * Completion block for animation trigged by inital animation completion.
   * I know...it is a mouth full
   */

  void (^vt_completion_animation_completion_block)(BOOL) = ^(BOOL finished){};
  
  switch (animation) {
    case EPBUIViewAnimationTransitionFadeIn: {
      
      [toViewController.view addImageSubview:overlayName
                                   withFrame:CGRectZero 
                                         tag:standardImageTag];
      
      [toViewController.view viewWithTag:standardImageTag].frame = aFrame;
      
      vt_animation_block = ^{
      
        fromViewController.view.alpha = 0.0f;

        [toViewController.view viewWithTag:standardImageTag].frame = toViewController.view.bounds;
      };
      
      vt_completion_animation_block = ^{
        [toViewController.view viewWithTag:standardImageTag].alpha = 0.0f;
      };
      
      vt_completion_animation_completion_block = ^(BOOL finished) {

        [[toViewController.view viewWithTag:standardImageTag] removeFromSuperview];
        
        [toViewController didMoveToParentViewController:self];
        [fromViewController removeFromParentViewController];
      };
      
      break;
    }
    case EPBUIViewAnimationTransitionFadeOut: {
      
      [fromViewController.view addImageSubview:overlayName
                                     withFrame:fromViewController.view.frame 
                                           tag:standardImageTag];
      
      vt_animation_block = ^{
        
        toViewController.view.alpha = 1.0f;
       
        [fromViewController.view viewWithTag:standardImageTag].frame = self.originalImageFrame;
      };
      
      vt_completion_animation_block = ^{
        [fromViewController.view viewWithTag:standardImageTag].alpha = 0.0f;
      };
      
      vt_completion_animation_completion_block = ^(BOOL finished) {

        [[fromViewController.view viewWithTag:standardImageTag] removeFromSuperview];
        
        [toViewController didMoveToParentViewController:self];
        [fromViewController removeFromParentViewController];
      };

      break;
    }
    default: {
      _transitionType = EPBUIViewAnimationTransitionNone;
      break;
    }
  }
  
	/**
   * transition
   */

	[self transitionFromViewController:fromViewController
                    toViewController:toViewController
                            duration:0.5
                             options:UIViewAnimationOptionAllowAnimatedContent
                          animations:vt_animation_block
                          completion:^(BOOL finished) {
                            
                            [UIView animateWithDuration:0.5
                                             animations:vt_completion_animation_block
                                             completion:vt_completion_animation_completion_block
                            ];
                          }];
}