TRANSITIONTYPE.md

Creating a custom TransitionType

To create a custom TransitionType you have to modify an existing PresentrAnimation or create your own. Then initialize a .custom TransitionType with your animation.

Modify an existing one

Here we get the existing CoverVerticalAnimation and modify it to create a CoverVerticalWithSpring transition.

let animation = CoverVerticalAnimation(options: .spring(duration: 2.0,
                                                        delay: 0,
                                                        damping: 0.5,
                                                        velocity: 0))
                                                        
let coverVerticalWithSpring = TransitionType.custom(animation)

presenter.transitionType = coverVerticalWithSpring
presenter.dismissTransitionType = coverVerticalWithSpring

You can initialize any PresentrAnimation subclass with an AnimationOptions enum that sets the UIView animation settings to be used.

public enum AnimationOptions {

    case normal(duration: TimeInterval)
    case spring(duration: TimeInterval, delay: TimeInterval, damping: CGFloat, velocity: CGFloat)

}

For example, if you wanted to modify the CrossDissolve transition to be much slower, you would do it like so:

let slowCrossDissolve = CrossDissolveAnimation(options: .normal(duration: 2.0))
presenter.transitionType = TransitionType.custom(slowCrossDissolve)

These are the included PresentrAnimation's mapped to their PresentationType.

func animation() -> PresentrAnimation {
    switch self {
    case .crossDissolve:
        return CrossDissolveAnimation()
    case .coverVertical:
        return CoverVerticalAnimation()
    case .coverVerticalFromTop:
        return CoverVerticalFromTopAnimation()
    case .coverHorizontalFromRight:
        return CoverHorizontalAnimation(fromRight: true)
    case .coverHorizontalFromLeft:
        return CoverHorizontalAnimation(fromRight: false)
    ...
    }
}

Create your own custom PresentrAnimation

• Create a class that inherits from PresentrAnimation.

Then, either:

• Override the transform method. It receives the Container Frame and Final Frame of the presented view controller. You need to return the Initial frame you want for the view controller, that way you can create a simple movement animation.

class ExpandFromCornerAnimation: PresentrAnimation {

    override func transform(containerFrame: CGRect, finalFrame: CGRect) -> CGRect {
        return CGRect(x: 0, y: 0, width: 10, height: 10)
    }

}

OR

• Override both beforeAnimation and performAnimation, and optionally, afterAnimation. Take the built-in CrossDissolveAnimation as an example.

public class CrossDissolveAnimation: PresentrAnimation {

    override public func beforeAnimation(using transitionContext: PresentrTransitionContext) {
        transitionContext.animatingView?.alpha = transitionContext.isPresenting ? 0.0 : 1.0
    }

    override public func performAnimation(using transitionContext: PresentrTransitionContext) {
        transitionContext.animatingView?.alpha = transitionContext.isPresenting ? 1.0 : 0.0
    }

    override public func afterAnimation(using transitionContext: PresentrTransitionContext) {
        transitionContext.animatingView?.alpha = 1.0
    }

}

The framework gives you all you need via the PresentrTransitionContext struct which is a wrapper which gives you all you need for the animation.

public struct PresentrTransitionContext {

    let containerView: UIView

    let initialFrame: CGRect

    let finalFrame: CGRect

    let isPresenting: Bool

    let fromViewController: UIViewController?

    let toViewController: UIViewController?

    let fromView: UIView?

    let toView: UIView?

    let animatingViewController: UIViewController?
    
    let animatingView: UIView?
    
}

Finally, create a custom TransitionType with your custom animation.

presenter.transitionType = .custom(ExpandFromCornerAnimation())