Difference between viewDidLoad and viewDidAppear

by

viewDidLoad is called exactly once, when the view controller is first loaded into memory. This is where you want to instantiate any instance variables and build any views that live for the entire lifecycle of this view controller. However, the view is usually not yet visible at this point.

viewDidAppear is called when the view is actually visible, and can be called multiple times during the lifecycle of a View Controller (for instance, when a Modal View Controller is dismissed and the view becomes visible again). This is where you want to perform any layout actions or do any drawing in the UI – for example, presenting a modal view controller. However, anything you do here should be repeatable. It’s best not to retain things here, or else you’ll get memory leaks if you don’t release them when the view disappears.

See: https://developer.apple.com/documentation/uikit/uiviewcontroller

More Related Contents:

  1. get UITextField Tag in Custom Methods
  2. Dynamic UITableViewCell
  3. Label doesn’t show text
  4. How can I scan barcodes on iOS? [closed]
  5. iOS 7 TableView like in Settings App on iPad
  6. Understanding NSRunLoop
  7. UIView and initWithFrame and a NIB file. How can I get the NIB file loaded?
  8. Converting escaped UTF8 characters back to their original form
  9. How to present popover properly in iOS 8
  10. NSPersistentContainer concurrency for saving to core data
  11. React Native Responsive Font Size
  12. How to format a Double into Currency – Swift 3
  13. How do I apply UIAppearance Proxy properties to UILabel?
  14. Access the camera with iOS
  15. How is layoutIfNeeded used?
  16. cocoapods not installing
  17. How to remove cache in WKWebview?
  18. How to change the tint color of the clear button on a UITextField
  19. How can I programmatically determine if my app is running in the iphone simulator?
  20. Rotation methods deprecated, equivalent of ‘didRotateFromInterfaceOrientation’?
  21. Why am I getting ibtool failed with exit code 255?
  22. Xcode 8 – Missing Files warnings
  23. Create a copy of a UIView in Swift
  24. The bundle’s Info.plist does not contain a CFBundleVersion key or its value is not a string
  25. How to mask UIViews in iOS
  26. How can I show a view on the first launch only?
  27. iOS – ‘MyProject-Swift.h’ file not found when running Unit Tests for Swift
  28. Facebook Graph API GET request – Should contain “fields” parameter (Swift, Facebook SDK v4.5.1)
  29. `-webkit-overflow-scrolling: touch` broken for initially offscreen elements in iOS7
  30. Two colors for UILabel TEXT

Leave a Comment