custom transition doesn't work when modal with transparent background

[chaiyixiao]

I was trying to implement a transparent modal in my project referencing to your tutorial(Thanks for sharing: ] ), as it's doesn't cover full screen, In addition to destinationViewController.transitioningDelegate = self destinationViewController.interactor = interaction, I need to add self.definesPresentationContext = true(<- Important) destinationViewController.modalPresentationStyle = .OverCurrentContext in prepareForSegue for presentingViewController. However, then problem happened that transitioning delegate ( not to say interactor). I tried to search online, but still couldn't get a clue. Do you have any idea what might help?

Many thanks! Yixiao

[chenr2]

Hi @chaiyixiao,

My understanding of the issue is that after setting .OverCurrentContext, the presenting view controller disappears and you get a black screen after you dismiss the modal. Is this correct?

I created a new branch that hopefully fixes the issue: https://github.com/ThornTechPublic/InteractiveModal/tree/chaiyixiao

.OverFullScreen and .OverCurrentContext are certainly useful when making semi-transparent modals. And definesPresentationContext is useful in making sure the presenting VC stays on-screen.

But I think as soon as we take control of the transitioning animation, it's difficult to merge our custom implementation with whatever magic Apple is doing with each modal presentation style.

I was able to get the semi-transparent modal effect by doing the following:

• Set the Modal's root View background color to Clear Color.
• Added a semi-transparent child View (white, alpha = 0.5) to the Modal
• Created a PresentAnimator, much like the DismissAnimator
• Wired up the PresentAnimator within the ViewController's animationControllerForPresentedController

The PresentAnimator does the following:

• Adds the Modal's view (toVC) on top of the ViewController's view (fromVC)
• Stages the Modal exactly one screen below
• Creates a snapshot of the ViewController (fromVC), and adds it to the container
• Animates the Modal to the center of the screen

The key step is creating a snapshot of the fromVC. By default, the fromVC is removed at the end of a transition. But the snapshot gives the illusion that it's still there.

Note: I did not use .OverCurrentContext nor definesPresentationContext. I'm sure there's probably a better solution that leverages the use of .OverCurrentContext, but I don't know enough about what's going on behind the scenes to figure it out.

[chaiyixiao]

Hi @chenr2,

Thank you so much for your reply. Your way is simple and works perfectly. I was trying to hold the presentingView in AnimationController during dismissal, but the code got ugly :(

Thanks again : ]