transitionFromViewControllertoViewControllerdurationoptionscompletion

The `transitionFromViewController:toViewController:duration:options:completion:` method is a powerful tool within the UIKit framework for animating the transition between two view controllers on the same parent view controller. It allows for custom presentation styles beyond the standard push or modal transitions.

This method is part of the `UIViewController` class and is typically invoked when a parent view controller needs to swap out one of its child view controllers for another. The core parameters dictate the behavior of the animation. The `duration` parameter specifies how long the transition will take in seconds. The `options` parameter accepts a bitmask that modifies the animation's timing curve and style. Common options include `.curveEaseInOut` for a smooth acceleration and deceleration, and `.transitionFlipFromLeft` for a flipping effect. The `completion` parameter is a block of code that is executed once the animation has finished, allowing for any necessary post-transition setup or cleanup.

When this method is called, the source view controller is removed from its superview, and the destination view controller is added to the superview. The animation is then applied to this change. It's important to manage the view controller containment hierarchy correctly when using this method, ensuring that the parent view controller is properly set as the container for both the source and destination view controllers. This method is often used for creating custom tab bar interfaces or complex page-turning effects.