Swift: Problems with custom UIView.transition? - ios

Question

Ok, I have looked through https://developer.apple.com/videos/play/wwdc2013/218/ and SO questions similarly trying to make custom transitions with a tab bar controller and its viewcontrollers but Im running into confusion after figuring out the main steps here.
I need to know how (meaning example code would be really helpful) to call a custom UIView.transition OR just have a custom option in UIView.transition. I need to use this to make a sliding/modal -mimicking transition between tabs in my tab bar controller.
The only way I can get a transition to happen is using the below function (this makes them dissolve):
func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {
if selectedViewController == nil || viewController == selectedViewController {
return false
}
let fromView = selectedViewController!.view
let toView = viewController.view
UIView.transition(from: fromView!, to: toView!, duration: 0.3, options: [.transitionCrossDissolve], completion: nil)
return true
}
And calling it manually here where I programmatically chnage the *selectedIndex* for my tab controller:
//SWITCHES BUTTON -------------------------------------------
func switchTab(index: Int)
{
//transition
self.tabBarController(self, shouldSelect: (viewControllers?[index])!)
I have read about and tried making a custom class UIViewControllerAnimatedTransitioning but don't know how this would fit in programmatically here -
my attempts passing my tab bar controller and the toView and fromViewinto the custom class result in nothing happening/animating. That is why Ive resorted to UIView.transition here.
How can I make a custom UIView.transition? What can I do here?

Answer 1

You should conform to UITabBarControllerDelegate
and Create a customTransition class and pass it as follows:
func tabBarController(_ tabBarController: UITabBarController, animationControllerForTransitionFrom fromVC: UIViewController, to toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? {
let animator = TabAnimationManager()
return animator
}
And Class TabAnimationManager should be a subclass of UIPercentDrivenInteractiveTransition and conform UIViewControllerAnimatedTransitioning protocol. You can add your custom animations in that class.