在官方文档中解释状态转换:https://developer.apple.com/library/ios/documentation/uikit/reference/UIViewController_Class/index.html

这张图片显示了各种视图' will '和' did '回调方法之间的有效状态转换

有效的状态转换:

取自:https://developer.apple.com/library/ios/documentation/uikit/reference/UIViewController_Class/Art/UIViewController类Reference_2x.png

图中没有提到viewWillLayoutSubviews和viewDidLayoutSubviews方法，但是在viewWillAppear和viewDidAppear之间调用这些方法。它们可以被多次调用。

在官方文档中解释状态转换:https://developer.apple.com/library/ios/documentation/uikit/reference/UIViewController_Class/index.html

这张图片显示了各种视图' will '和' did '回调方法之间的有效状态转换

有效的状态转换:

取自:https://developer.apple.com/library/ios/documentation/uikit/reference/UIViewController_Class/Art/UIViewController类Reference_2x.png

iOS 6及以后版本。新的图表如下:

让我们集中在方法上，它们负责UIViewController的生命周期:

Creation: - (void)init - (void)initWithNibName: View creation: - (BOOL)isViewLoaded - (void)loadView - (void)viewDidLoad - (UIView *)initWithFrame:(CGRect)frame - (UIView *)initWithCoder:(NSCoder *)coder Handling of view state changing: - (void)viewDidLoad - (void)viewWillAppear:(BOOL)animated - (void)viewDidAppear:(BOOL)animated - (void)viewWillDisappear:(BOOL)animated - (void)viewDidDisappear:(BOOL)animated - (void)viewDidUnload Memory warning handling: - (void)didReceiveMemoryWarning Deallocation - (void)viewDidUnload - (void)dealloc

更多信息请查看UIViewController类参考。

根据苹果的文件-开始开发iOS应用程序(Swift) -使用视图控制器-理解视图控制器生命周期

viewDidLoad()—Called when the view controller’s content view (the top of its view hierarchy) is created and loaded from a storyboard. … Use this method to perform any additional setup required by your view controller. viewWillAppear()—Called just before the view controller’s content view is added to the app’s view hierarchy. Use this method to trigger any operations that need to occur before the content view is presented onscreen viewDidAppear()—Called just after the view controller’s content view has been added to the app’s view hierarchy. Use this method to trigger any operations that need to occur as soon as the view is presented onscreen, such as fetching data or showing an animation. viewWillDisappear()—Called just before the view controller’s content view is removed from the app’s view hierarchy. Use this method to perform cleanup tasks like committing changes or resigning the first responder status. viewDidDisappear()—Called just after the view controller’s content view has been removed from the app’s view hierarchy. Use this method to perform additional teardown activities.