[IOS筆記] - addChildViewController

View Controller中可以添加多個sub view，在需要的時候顯示出來；

可以通過viewController(parent)中可以添加多個child viewController;來控制頁面中的sub view，降低代碼耦合度；

通過切換，可以顯示不同的view；，替代之前的addSubView的管理

 

　　 //在parent view controller 中添加 child view controller
　　 FirstViewController *firstViewController=[[FirstViewController alloc] initWithNibName:@"FirstViewController" bundle:nil];
    [self addChildViewController:firstViewController];
    
    SecondViewController *secondViewController=[[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle:nil];
    [self addChildViewController:secondViewController];
    
    ThirdViewController *thirdViewController=[[ThirdViewController alloc] initWithNibName:@"ThirdViewController" bundle:nil];
    [self addChildViewController:thirdViewController];
    
    [self.view  addSubview:thirdViewController.view];

　　// addChildViewController回調用[child willMoveToParentViewController:self] ，但是不會調用didMoveToParentViewController，所以需要顯示調用
    [thirdViewController didMoveToParentViewController:self];
    currentViewController=thirdViewController;
    
　　//切換child view controller
     [self transitionFromViewController:currentViewController toViewController:firstViewController duration:4 options:UIViewAnimationOptionTransitionFlipFromLeft animations:^{
            }  completion:^(BOOL finished) {
               //......
            }];
    currentViewController=firstViewController;

　　//移除child view controller
    // removeFromParentViewController在移除child前不會調用[self willMoveToParentViewController:nil] ，所以需要顯示調用
    [currentViewController willMoveToParentViewController:nil];
    [currentViewController removeFromSuperview];
    [currentViewController removeFromParentViewController];