海德尔的答案适用于ios 6之前的版本。然而，在iOS 6中，viewDidUnload和viewWillUnload从未被调用。文档声明:“视图在低内存条件下不再被清除，因此该方法永远不会被调用。”

海德尔的答案适用于ios 6之前的版本。然而，在iOS 6中，viewDidUnload和viewWillUnload从未被调用。文档声明:“视图在低内存条件下不再被清除，因此该方法永远不会被调用。”

更新:ViewDidUnload在iOS 6中已弃用，因此更新了相应的答案。

UIViewController的生命周期如图所示:

使用Xamarin Native/Mono Touch的优势在于，它使用了原生api，因此它遵循与Apple文档中相同的ViewController生命周期。

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.

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

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。