使用Cocoa Touch如何為視圖控制器實現(xiàn)自定義展示和過渡效果

要為視圖控制器實現(xiàn)自定義展示和過渡效果，可以使用UIViewControllerTransitioningDelegate協(xié)議和UIViewControllerAnimatedTransitioning協(xié)議來實現(xiàn)。以下是一個簡單的示例：

1. 創(chuàng)建一個自定義的轉(zhuǎn)場動畫類CustomTransitionAnimator，實現(xiàn)UIViewControllerAnimatedTransitioning協(xié)議：

import UIKit

class CustomTransitionAnimator: NSObject, UIViewControllerAnimatedTransitioning {
    
    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
        return 0.5
    }
    
    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
        guard let fromVC = transitionContext.viewController(forKey: .from),
              let toVC = transitionContext.viewController(forKey: .to),
              let containerView = transitionContext.containerView else {
            return
        }
        
        containerView.addSubview(toVC.view)
        toVC.view.alpha = 0.0
        
        UIView.animate(withDuration: transitionDuration(using: transitionContext), animations: {
            toVC.view.alpha = 1.0
        }) { _ in
            transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
        }
    }
    
}

2. 在視圖控制器中設(shè)置transitioningDelegate，并實現(xiàn)UIViewControllerTransitioningDelegate協(xié)議方法：

class ViewController: UIViewController, UIViewControllerTransitioningDelegate {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        transitioningDelegate = self
    }
    
    func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        return CustomTransitionAnimator()
    }
    
    func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        return CustomTransitionAnimator()
    }
    
}

現(xiàn)在，當(dāng)你展示或dismiss這個視圖控制器時，將會使用你自定義的轉(zhuǎn)場動畫效果。