前言
在开发中，无论我们使用 Push 还是 Present 推出新的 ViewController 时，系统为了提高用户体验都会为我们默认加上一些过渡动画。但是，系统默认的动画总是不能满足大家各种各样的需求的，所以系统也为我们提供了在不同场景下自定义过渡动画以及通过手势控制过渡进度的实现方案。
这篇文章记录了自定义转场动画中的几种情况：
效果图
预备
首先，我们现在介绍几个在自定义转场动画时需要接触的协议：
我们在定义好了实现上面两个协议的类后，只需要在需要进行转场的地方，提供对应的对象即可。
ps：下面的实例中，请大家忽略动画效果，关注实现。(其实是懒得去写太多动画了。🤦♂️)
模态跳转（Present）
场景
self.present(vc!, animated: true) {} self.dismiss(animated: true) {} 实现步骤
需要实现的UIViewControllerTransitioningDelegate方法：
//返回用于 present 的自定义 transition 动画optional func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? //返回用于 dismiss 的自定义 transition 动画optional func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning?
实例
/// 第一个 VC 中点击跳转func presentClick(_ sender: Any) { let vc = self.storyboard?.instantiateViewController(withIdentifier: "PresentSecondViewController") vc?.modalPresentationStyle = .fullScreen vc?.transitioningDelegate = self self.present(vc!, animated: true) {}}// 第一个 VC 实现协议，返回控制转场动画效果的实例extension PresentFirstViewController: UIViewControllerTransitioningDelegate { func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? { return NormalPresentAnimator() } func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? { return NormalPresentAnimator() }}导航控制器跳转（Push）
场景
self.navigationController?.pushViewController(vc!, animated: true)self.navigationController?.popViewController(animated: true)
实现步骤
需要实现的UINavigationControllerDelegate方法：
optional func navigationController(_ navigationController: UINavigationController, animationControllerFor operation: UINavigationController.Operation, from fromVC: UIViewController, to toVC: UIViewController) -> UIViewControllerAnimatedTransitioning?
实例
class PushFirstViewController: UIViewController { override func viewDidLoad() { super.viewDidLoad() self.navigationController?.delegate = self } @IBAction func pushClick(_ sender: Any) { let vc = self.storyboard?.instantiateViewController(withIdentifier: "PushSecondViewController") self.navigationController?.pushViewController(vc!, animated: true) }}extension PushFirstViewController: UINavigationControllerDelegate { //返回自定义过渡动画 func navigationController(_ navigationController: UINavigationController, animationControllerFor operation: UINavigationController.Operation, from fromVC: UIViewController, to toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? { if operation == .pop && fromVC is PushFirstViewController { return nil } return NormalPushAnimator() }}UITabbarController
在前面的两个专场实现中，我们在需要转场的类中分别实现了UIViewControllerTransitioningDelegate 及 UINavigationControllerDelegate 方法，在这两个协议中，还有这样几个方法：
/// UIViewControllerTransitioningDelegateoptional func interactionControllerForPresentation(using animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning?optional func interactionControllerForDismissal(using animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning?/// UINavigationControllerDelegateoptional func navigationController(_ navigationController: UINavigationController, interactionControllerFor animationController: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning?
上面这几个方法呢？其实就是我们通过利用手势转场时过渡的进度处理方法。我们需要在代理方法中返回一个实现了 UIViewControllerInteractiveTransitioning 协议的对象来对转场进度进行控制。下面的 UITabbarController 中我就实现一个利用手势控制转场的例子。 Present 及 Push/Pop 按照相同的思路实现即可。
场景
UITabbarController 在默认的状态下，切换控制器时是没有动画效果的。如果需要动画效果的话，需要我们进行自定义。
实现步骤
/// 返回实现了 UIViewControllerAnimatedTransitioning 协议的实例func tabBarController(_ tabBarController: UITabBarController, animationControllerForTransitionFrom fromVC: UIViewController, to toVC: UIViewController) -> UIViewControllerAnimatedTransitioning?/// 返回实现了 UIViewControllerInteractiveTransitioning 协议的实例 func tabBarController(_ tabBarController: UITabBarController, interactionControllerFor animationController: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning?
实例
class TabbarController: UITabBarController, UITabBarControllerDelegate { override func viewDidLoad() { super.viewDidLoad() self.delegate = self}func tabBarController(_ tabBarController: UITabBarController, animationControllerForTransitionFrom fromVC: UIViewController, to toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? { if self.selectedIndex == 0 { return TabbarAnimator(edge: .right) } else { return TabbarAnimator(edge: .left) }} func tabBarController(_ tabBarController: UITabBarController, interactionControllerFor animationController: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning? { if self.panGesture.state == .began || self.panGesture.state == .changed { return TabbarInteractionTransition(pan: self.panGesture) } else { return nil }}三方框架――Lottie
介绍
Lottie 是 Android 和 iOS 的移动库，用 bodymovin 解析 Adobe After Effects 导出为 json 的动画并在移动设备上生成矢量动画。设计师可以轻松的创建漂亮(复杂)的动画，无需程序员辛苦地手动去创建及调试。
场景
实现一些特殊的转场，且程序员无足够时间调试动画时。
实现步骤
ps：Lottie 转场的 LOTAnimationTransitionController 在 3.0.0 版本后被移除，所以需要使用 Lottie 做转场时，需要在导入时，指定版本号为更早的版本。我这里使用的是 2.5.3。
实例
/// 第一个 VCfunc presentClick(_ sender: Any) { let vc = self.storyboard?.instantiateViewController(withIdentifier: "LottieSecondViewController") vc?.transitioningDelegate = self self.present(vc!, animated: true) {}}/// 实现 UIViewControllerTransitioningDelegate，返回 LOTAnimationTransitionController 的实例extension LottieFirstViewController: UIViewControllerTransitioningDelegate { func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? { let transitionController = LOTAnimationTransitionController(animationNamed: "Count", fromLayerNamed: "", toLayerNamed: "", applyAnimationTransform: false) return transitionController } func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? { let transitionController = LOTAnimationTransitionController(animationNamed: "Three", fromLayerNamed: "", toLayerNamed: "", applyAnimationTransform: false) return transitionController }}总结
上面的所有动画的示例可以在我的Github上找到哦，各位前快去下载把玩吧。
好的转场动画，在用户交互上会带来更加美妙的体验。让用户尽享丝滑哦。
好了，以上就是这篇文章的全部内容了，希望本文的内容对大家的学习或者工作具有一定的参考学习价值，谢谢大家对武林网的支持。
新闻热点
疑难解答
