iOS中ViewController的切换

• iOS中ViewController的切换方式一般有：push,modal,tabbar,childViewController几种。

  push

  视图控制容器（View Controller Container）

  UINavgationController、UITabBarController、UISplitViewController等都属于view controller container这些类的共性是都有一个类型为数组的对象viewControllers属性，用于保存一组视图控制器。
  任何view controller container对象都可以通过viewControllers属性来访问子对象（视图），而子对象也可以通过navigationController, tabbarController, splitViewController, parentViewController找到相应的view controller container。

• 情形：A->B->C，A push B，B push C，现在要从C直接回到A中

  // 直接修改ViewControllers堆栈信息：@[vcA,vcB,vcC]->@[vcA]
  [self.navigationController setViewControllers:@[vcA] animated:YES];

modal 模态视图

present

• present：当应用以模态形式显示一个视图时，即通过presentViewController: animated: completion:推出的视图，负责显示的控制器将是视图控制容器（View Controller Container）最顶部的视图，而负责推出的视图。
• presentingViewController：A present B，B的presentingViewController就是A

• presentedViewController：A present B，A的presentedViewController就是B

• 情形： tabbarController->navigationController->vcA，vcA present vcB

  [vcA presentViewController:vcB animated:YES completion:nil];
  NSLog(@"presenting:%@---prensented:%@",self.presentingViewController,self.presentedViewController);
  // presenting:<UITabBarController: 0x7f90a9013400>---prensented:(null)

若想让B的presentingViewController变成A：

vcB.modalPresentationStyle = UIModalPresentationCurrentContext;
self.definesPresentationContext = YES;
[vcA presentViewController:vcB animated:YES completion:nil];

dismiss

如果 A present B，那么A就有责任dismiss B，如果在B中调用[self dismissViewControllerAnimated…]就会A中发送dismiss，最终会由有A进行dismiss,相当于在B中执行[self.presentingViewController dismissViewControllerAnimated…]

• 情形：A->B->C(A present B,B present C)
  C dismiss： 结果就是B modal 出来的C被移除。B present C，那么B就有责任dismiss C，如果在C中调用[self dismissViewControllerAnimated…]就会B中发送dismiss，最终会由B进行dismiss，相当于在C中执行[self.presentingViewController dismissViewControllerAnimated…]。
  B dismiss： 结果就是B modal 出来的 C 被移除。B自身并不会被移除。
  A dismiss：A modal 出来的B就会被移除，B modal 出的C因为B被移除了，C自己也就被移除了。不过移除动画只有B被移除的动画被显示，C的移除动画是没有的。

使用

vcB

@protocol ModalViewControllerDelegate <NSObject>
-(void) modalViewControllerDidClickedDismissButton:(ModalViewController *)viewController;

@property (nonatomic, weak) id<ModalViewControllerDelegate> delegate;

if (self.delegate && [self.delegate respondsToSelector:@selector(modalViewControllerDidClickedDismissButton:)]) {
[self.delegate modalViewControllerDidClickedDismissButton:self];
}

vcA

//遵循<ModalViewControllerDelegate>，实现协议方法
-(void)modalViewControllerDidClickedDismissButton:(ModalViewController *)viewController {
[self dismissViewControllerAnimated:YES completion:nil];
}

自定义模态动画效果

1.新建一个类来实现自定义动画

// 遵循<UIViewControllerAnimatedTransitioning>，实现协议方法
- (NSTimeInterval)transitionDuration:(id <UIViewControllerContextTransitioning>)transitionContext
{
return 0.8f;
}

- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext
{
// 1. Get controllers from transition context
UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];

// 2. Set init frame for toVC
CGRect screenBounds = [[UIScreen mainScreen] bounds];
CGRect finalFrame = [transitionContext finalFrameForViewController:toVC];
toVC.view.frame = CGRectOffset(finalFrame, 0, screenBounds.size.height);

// 3. Add toVC's view to containerView
UIView *containerView = [transitionContext containerView];
[containerView addSubview:toVC.view];

// 4. Do animate now
NSTimeInterval duration = [self transitionDuration:transitionContext];
[UIView animateWithDuration:duration
delay:0.0
usingSpringWithDamping:0.6
initialSpringVelocity:0.0
options:UIViewAnimationOptionCurveLinear
animations:^{
toVC.view.frame = finalFrame;
} completion:^(BOOL finished) {
// 5. Tell context that we completed.
[transitionContext completeTransition:YES];
}];
}

2.使用这个自定义动画

// 1.初始化自定义动画的类对象
// 2.遵循UIViewControllerTransitioningDelegate
mvc.transitioningDelegate = self;
[self presentViewController:mvc animated:YES completion:nil];

// 3.实现协议方法
- (id <UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source {
    return self.presentAnimation;
}

childViewController

添加childViewController

[self addChildViewController: childVC]： 会调用 childVC 的 willMoveToParentViewController: 方法和 didMoveToParentViewController:方法
[self.addSubview:childVC.view]会调用childVC的viewDidLoad方法。

SecondViewController *secondVC = [[SecondViewController alloc]init];
secondVC.view.frame = self.view.bounds;
[self addChildViewController:secondVC];//1 vc
[self.view addSubview:secondVC.view];//2 view
[secondVC didMoveToParentViewController:self];//3 didmove

移除一个Controller:

//移除childVC，但在removeFromParentViewController：方法前不会调用willMoveToParentViewController:nil 方法，所以需要显式调用
[childVC willMoveToParentViewController:nil]; //1 willmove
[childVC.view removeFromSuperview]; //2 view
[childVC removeFromParentViewController]; //3 vc

viewWillAppear & viewDidAppear

Controller里面的viewWillAppear:(BOOL)animated在subview真正加到父view之前调用，viewDidAppear:(BOOL)animated在真正被add到父view之后调用，视图消失也是一样。

[towCol beginAppearanceTransition:YES animated:YES]触发towCol的viewWillAppear，[towCol beginAppearanceTransition:NO animated:YES]触发towCol的viewWillDisappear，和他们配套的[towCol endAppearanceTransition]分别触发viewDidAppear和viewDidDisappear

childViewController被添加后以下方法的执行顺序为：

willMoveToParentViewController:
viewDidLoad
viewWillAppear:
didMoveToParentViewController:
viewDidAppear:

childViewController被移除后以下方法的执行顺序为：

willMoveToParentViewController:
viewWillDisappear:
didMoveToParentViewController:
viewDidDisappear:

常见问题