如何不使用Storyboard实现ViewController间的转场动画？

当然没问题——Storyboard只是iOS开发中可视化构建界面的工具，自定义ViewController转场的核心是依靠UIViewControllerTransitioningDelegate和UIViewControllerAnimatedTransitioning协议，纯代码完全能实现你想要的效果。你已经搭建了正确的代码框架，我来帮你梳理细节和注意事项：

你的现有代码解析 #

你给出的代码已经走在正确的方向上：

1. 触发转场的方法：

   @objc func handleAccount() { 
       let navController = UINavigationController(rootViewController: userButtonLauncher()) 
       navController.transitioningDelegate = self 
       navController.modalPresentationStyle = .custom 
       self.present(navController, animated: true, completion: nil) 
   }
   

   这里通过代码实例化UINavigationController作为容器，设置transitioningDelegate为当前控制器，同时将modalPresentationStyle设为.custom——这是启用自定义转场的必要配置，非常正确。

2. 转场代理方法：

   func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? { 
       transition.transitionMode = .present 
       transition.startingPoint = CGPoint(x: 0, y: 0) 
       return transition 
   } 
    
   func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? { 
       transition.transitionMode = .pop 
       transition.startingPoint = CGPoint(x: 0, y: 0) 
       return transition 
   }
   

   你正确实现了UIViewControllerTransitioningDelegate的两个核心方法，分别为present和dismiss转场返回自定义的动画控制器，并且通过transitionMode区分了两种转场状态，这是自定义转场的关键逻辑。

关键注意事项 #

要让转场正常工作，还需要确保以下几点：

• 自定义动画控制器的实现：你代码中的transition对象必须是遵循UIViewControllerAnimatedTransitioning协议的自定义类，必须实现两个强制方法：
  • transitionDuration(using:)：返回转场动画的时长
  • animateTransition(using:)：编写具体的动画逻辑（比如缩放、平移、淡入淡出等）
• 状态重置：如果复用同一个transition实例，要确保每次转场前正确设置transitionMode和startingPoint（你已经做到了这一点）
• 内存管理：如果transition是当前控制器的属性，避免循环引用（比如不需要持有引用的话，可以每次创建新实例，或者用弱引用管理）

补充完整的自定义动画控制器示例 #

如果还没实现transition对应的类，这里给一个简单的缩放转场示例：

class CustomTransition: NSObject, UIViewControllerAnimatedTransitioning {
    // 定义转场模式
    enum TransitionMode {
        case present
        case dismiss
    }
    
    var transitionMode: TransitionMode = .present
    var startingPoint: CGPoint = .zero
    
    // 动画时长
    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
        return 0.3
    }
    
    // 核心动画逻辑
    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
        let containerView = transitionContext.containerView
        
        // 获取参与转场的视图控制器
        guard let toVC = transitionContext.viewController(forKey: .to),
              let fromVC = transitionContext.viewController(forKey: .from) else {
            transitionContext.completeTransition(false)
            return
        }
        
        switch transitionMode {
        case .present:
            // Present动画：从起始点缩放展开
            toVC.view.frame = CGRect(origin: startingPoint, size: CGSize(width: 10, height: 10))
            toVC.view.clipsToBounds = true
            toVC.view.layer.cornerRadius = 5
            containerView.addSubview(toVC.view)
            
            UIView.animate(withDuration: transitionDuration(using: transitionContext),
                           delay: 0,
                           usingSpringWithDamping: 0.8,
                           initialSpringVelocity: 0.5,
                           options: .curveEaseOut) {
                toVC.view.frame = containerView.bounds
                toVC.view.layer.cornerRadius = 0
            } _ in
                transitionContext.completeTransition(true)
            }
            
        case .dismiss:
            // Dismiss动画：缩放到起始点后消失
            UIView.animate(withDuration: transitionDuration(using: transitionContext), animations: {
                fromVC.view.frame = CGRect(origin: self.startingPoint, size: CGSize(width: 10, height: 10))
                fromVC.view.layer.cornerRadius = 5
            }) { _ in
                fromVC.view.removeFromSuperview()
                transitionContext.completeTransition(true)
            }
        }
    }
}

最终整合 #

在你的主ViewController中，只需声明遵循UIViewControllerTransitioningDelegate协议，并持有CustomTransition实例即可：

class MainViewController: UIViewController, UIViewControllerTransitioningDelegate {
    private let transition = CustomTransition()
    
    // ... 其他视图初始化、布局代码
    
    @objc func handleAccount() { 
        let targetVC = userButtonLauncher() // 你的目标ViewController
        let navController = UINavigationController(rootViewController: targetVC) 
        navController.transitioningDelegate = self 
        navController.modalPresentationStyle = .custom 
        present(navController, animated: true, completion: nil) 
    }
    
    // 实现转场代理方法
    func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? { 
        transition.transitionMode = .present 
        transition.startingPoint = CGPoint(x: 0, y: 0) // 可以根据需要调整起始点，比如按钮的位置
        return transition 
    } 
    
    func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? { 
        transition.transitionMode = .dismiss 
        transition.startingPoint = CGPoint(x: 0, y: 0) 
        return transition 
    }
}

这样就能完全脱离Storyboard实现自定义转场动画了，整个流程都是纯代码控制，灵活性更高。

内容的提问来源于stack exchange，提问作者eksglox