UINavigationController就一本书一样，而UIViewController就是它的每一页，我们可以一页一页的翻，也可以瞬间跳到某一页，或者回归的过去的某一页。
构成
我们首先要有一个rootViewController，装进UINavigationController。
例如在AppDelegate的didFinishLaunchingWithOptions中
let navVC = UINavigationController(rootViewController: ViewController())
window?.rootViewController = navVC
window?.backgroundColor = UIColor.gray
window?.makeKeyAndVisible()
用ViewController()创建一个UIViewController来初始化UINavigationController, 这样ViewController()作为导航栏的第一页显示出来。
UINavigationController的组成， 引用一下官网的
UI元素除了UIViewController的数组外，还有navigationBar，toolbar。
接下里我们丰富一下，将其UI元素全部用上。
在ViewController的viewDidLoad中加入代码
// 显示toolbar
self.navigationController?.isToolbarHidden = false
self.setToolbarItems([UIBarButtonItem(barButtonSystemItem: .camera, target: nil, action: nil), UIBarButtonItem(barButtonSystemItem: .bookmarks, target: nil, action: nil)], animated: false)
// 设置navigationBar的title
self.title = "root view"
// 设置navigationBar按钮
self.navigationItem.setLeftBarButton(UIBarButtonItem(barButtonSystemItem: .add, target: nil, action: nil), animated: false)
self.navigationItem.setRightBarButton(UIBarButtonItem(barButtonSystemItem: .done, target: nil, action: nil), animated: false)
注意：toolbar的items的设置，是与UIViewController关联的，不要UINavigationController上setItems是不会显示的
跳转
Push
push就是将VC一个一个叠上去，默认行为是从右侧进入
self.navigationItem.setRightBarButton(UIBarButtonItem(barButtonSystemItem: .done, target: self, action: #selector(self.pushAction(sender:))), animated: false)
func pushAction(sender:UIBarButtonItem) {
self.navigationController?.pushViewController(ViewController2(), animated: true)
}
我们将done按钮加入push动作, 点击done，从右到左进入，这时候系统会添加一个navigationBar item，用于pop到下层页面，title就是下层页面设置的title
push对应的返回接口是pop
self.navigationController?.popViewController(animated: true)
Present
说道跳转，这里也提一下present，present跳到另外一个页面，默认行为是从下而上，除了表现上与push不一样
- 不是UINavigationController的管理范畴，UIViewController可直接
present到其他页面 - 同一个
UIViewController不可以present两次，但present起来的vc是可以再次present的 -
present类似模态窗口，在这个窗口dissmiss前，交互只能在这个窗口做，之前的页面不可交互和变化, 就仿佛你放下一本书，就拿起另外一本书，不能同时看两本书
present对应的消失接口是dissmiss
self.dismiss(animated: true, completion: nil)
Show
8.0以后提供了show方法，这个是根据viewController所处容器，使用容器的跳转行为，例如viewController所处容器为navigationController(viewController的容器还有splitViewController)，就和push一样
open func show(_ vc: UIViewController, sender: Any?)
自定义跳转方式（转场动画）
自定义转场动画，需要制定两个因素
- 从哪个viewController跳转到哪个viewController
- 动画内容
自定义 Present
我们尝试改写present的动画效果，它默认是由下而上，改成自上而下
func pushAction(sender:UIBarButtonItem) {
let vc = ViewController2()
vc.transitioningDelegate = self // 实现UIViewControllerTransitioningDelegate协议
self.present(vc, animated: true, completion: nil)
}
实现UIViewControllerTransitioningDelegate协议, 下面就是用来实现，present和dismiss动画的
@available(iOS 2.0, *)
optional public func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning?
@available(iOS 2.0, *)
optional public func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning?
这两个接口需要返回id<UIViewControllerAnimatedTransitioning>
UIViewControllerAnimatedTransitioning
// 转场时间
public func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval
// 动画
public func animateTransition(using transitionContext: UIViewControllerContextTransitioning)
接下来需要创建一个id<UIViewControllerAnimatedTransitioning>的类，
class PresentAnimator: NSObject, UIViewControllerAnimatedTransitioning {
func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
return 1
}
func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
let fromViewController = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.from)
let toViewController = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.to)
let containerView = transitionContext.containerView
// 将跳转后的页面，设置到屏幕上方
toViewController?.view.frame = (fromViewController?.view.frame)!
toViewController?.view.frame.origin.y -= (toViewController?.view.frame.height)!
// 添加到转场动画容器上，
containerView.addSubview((toViewController?.view)!)
UIView.animate(withDuration: transitionDuration(using: transitionContext), animations: { () -> Void in
// 回归的屏幕位置
toViewController?.view.frame = (fromViewController?.view.frame)!
}, completion: { (complete:Bool) -> Void in
transitionContext.completeTransition(true)
})
}
}
经过我打印地址研究，得出以下结论
- containerView是做动画用的容器, 初始状态是将跳转前页面(较为顶层的一个view，如果vc在navigationController中就是naviController的view)添加为自己的subview
- fromViewController不是跳转前vc, 只是将跳转前页面添加为自己的subview，用来做旧页面的退出动画
- toViewController则是跳转后vc，做新页面的登台动画
- transitionDuration时间是提供给系统的，提供跳转时系统的默认表现，自定义animate的时间最好和其保持一致
- containerView临时产生，在动画结束后，从UI上撤掉，但view的改变会遗留下来
注意：transitionContext.completeTransition(true)是必须要调用的，否则系统认为转场为完成，第二页不能进行任何交互
自定义 Dismiss
dismiss 与 present 类似，只是fromViewController变成了第二页，toViewController变成了第一页, 记住上述的那几条结论来理解containerView.addSubview
class DismissAnimator: NSObject, UIViewControllerAnimatedTransitioning {
func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
return 2
}
func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
let fromViewController = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.from)
let toViewController = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.to)
let containerView = transitionContext.containerView
containerView.addSubview((toViewController?.view)!)
containerView.addSubview((fromViewController?.view)!)
UIView.animate(withDuration: transitionDuration(using: transitionContext), animations: { () -> Void in
fromViewController?.view.alpha = 0.0
}, completion: { (complete:Bool) -> Void in
transitionContext.completeTransition(true)
})
}
}
自定义 Push
只是挂接delegate的位置不同
// 自定义navigationController动画
self.navigationController?.delegate = self
实现同样和上面一样，返回id<UIViewControllerAnimatedTransitioning>, 为了简单，我们做之前present和dismiss一样的动画
func navigationController(_ navigationController: UINavigationController, animationControllerFor operation: UINavigationControllerOperation, from fromVC: UIViewController, to toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? {
if operation == .push {
return PresentAnimator();
} else {
return DismissAnimator();
}
}
交互式动画
最后在说一个present的交互动画
交互式动画就随手势做的动画，手拖的距离，来决定动画执行的进度
需要再实现UIViewControllerTransitioningDelegate协议中的交互式接口，要求返回一个id<UIViewControllerInteractiveTransitioning>
optional public func interactionControllerForPresentation(using animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning?
optional public func interactionControllerForDismissal(using animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning?
这个交互式动画，依赖于之前设置的动画方式，只是用来设置百分比，这个百分比需要你自己不断提供给他，一般用手势来不断调用id<UIViewControllerInteractiveTransitioning>的update接口，我们为了简单，用timer来模拟
创建一个id<UIViewControllerInteractiveTransitioning>
class InteractiveAnimator: UIPercentDrivenInteractiveTransition {
}
viewController中加入属性
var interactiveAnimator:InteractiveAnimator = InteractiveAnimator()
var timer:Timer? = nil
var times:CGFloat = 0;
修改接口
func interactionControllerForPresentation(using animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning?
{
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(self.timeUpdate), userInfo: nil, repeats: true);
return interactiveAnimator
}
func interactionControllerForDismissal(using animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning?
{
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(self.timeUpdate), userInfo: nil, repeats: true);
return interactiveAnimator
}
func timeUpdate() {
times += 1
if times <= 5 {
let per:CGFloat = times/5
interactiveAnimator.update(per)
} else {
timer?.invalidate()
interactiveAnimator.finish()
}
}
timeUpdate的会该5次百分比，这个动画也分5下完成, 每秒变化一次。timeUpdate这是里timer来调用的，你可以用任意的交互方式来调用，百分比自己来计算
demo 地址 记得 pod install
