Add/Remove a single child ViewController

[CustomContainers]SingleChildAnimated.m

// Add Remove child controllers to a custom container controller with Animations
// ADD THE CHILD CONTROLLER   
self.childController = theChildController;
self.childController.view.frame = setupInitialChildControllerFrame();
[self addChildViewController:self.childController];
[self.view addSubview:self.childController.view];
[self.childController didMoveToParentViewController:self];

[UIView animateWithDuration:1.0
                      delay:0.0
     usingSpringWithDamping:0.6
      initialSpringVelocity:0.3
                    options:UIViewAnimationOptionCurveEaseIn
                 animations:^{

                     self.childController.view.frame = setupFinalChildControllerFrame();

                 } completion:nil
 ];
   



// REMOVE THE CHILD CONTROLLER    
[self.childController willMoveToParentViewController:nil];

[UIView animateWithDuration:0.8
                      delay:0.0
     usingSpringWithDamping:0.6
      initialSpringVelocity:0.3
                    options:UIViewAnimationOptionCurveEaseIn
                 animations:^{
 
                     self.childController.view.frame = setupInitialChildControllerFrame();

                 } completion:^(BOOL complete){

                     [self.childController removeFromParentViewController];
                     self.childController = nil;
}];