iPhone Sdk: Differencebetween Loadview and Viewdidload

iPhone SDK: what is the difference between loadView and viewDidLoad?

I can guess what might be the problem here, because I've done it:

I've found that often when I add init code to loadView, I end up with an infinite stack trace

Don't read self.view in -loadView. Only set it, don't get it.

The self.view property accessor calls -loadView if the view isn't currently loaded. There's your infinite recursion.

The usual way to build the view programmatically in -loadView, as demonstrated in Apple's pre-Interface-Builder examples, is more like this:

UIView *view = [[UIView alloc] init...];
...
[view addSubview:whatever];
[view addSubview:whatever2];
...
self.view = view;
[view release];

And I don't blame you for not using IB. I've stuck with this method for all of Instapaper and find myself much more comfortable with it than dealing with IB's complexities, interface quirks, and unexpected behind-the-scenes behavior.

What is the difference between loadView and viewDidLoad?

When you load your view from a NIB and want to perform further customization after launch, use viewDidLoad.

If you want to create your view programatically (not using Interface Builder), use loadView.

Difference between viewDidLoad and loadView?

Do you mean viewDidLoad and loadView? viewDidLoad is a method called when your view has been fully loaded. That means all your IBOutlets are connected and you can make changes to labels, text fields, etc.

loadView is a method called if you're (typically) not loading from a nib. You can use this method to set up your view controller's view completely in code and avoid interface builder altogether.

You'll typically want to avoid loadView and stick to viewDidLoad.

Difference between viewDidAppear, viewDidLoad in iPhone/iOS?

A UIView object can get loaded into memory and released multiple times without ever getting added to the view stack and appearing on the display.

My guess is that you have 2 references to this view (maybe one in a nib file?), so it's getting loaded, then released when the second reference is loaded and assigned to the same property, then only the latter gets added to the view stack. You can see this by printing out (NSLog) the integer value of self ("%ld",(long int)self) in the viewDidLoad and viewDidAppear methods.

Difference between viewDidLoad and viewDidAppear

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

What is the difference between view 'did load' method and 'didFinishLaunching' application

applicationDidFinishLaunching is called by the App Delgate when your application has finished launching. This method is useful for doing setup as soon as possible. Examples of this could include setting up GameCenter, and doing some first launch checking.

viewDidLoad is called by a UIViewController after the view is loaded, usually from the nib. However, in some cases, you may want to do setup before the view is loaded. In that case, use

viewWillLoad is called just before the view is loaded, usually from the nib. For the most part, it will not make much of a difference wether you use viewDidLoad or viewWillLoad. However, some setup may have to be done after the view is loaded and other setup you may want to do before the screen displays anything.

applicationDidFinishLaunching is for initial appwide setup, viewWillLoad is for setup before the view is displayed, and viewDidLoad is for setup right after the view is loaded.

What is viewDidLoad() for?

viewDidLoad is the method that is called once the MainView of a ViewController has been loaded. This is called after loadView is called.In the image you can see the MainView and other views within it. As soon as MainView has been loaded whatever will be included within the MainView you can get access to it (YES, all the buttons, labels, etc) in the ViewDidLoad method.

I'm also confused about override. Does it add code to existent viewDidLoad()?

As we know if subclass provides the specific implementation of the method that has been provided by one of its parent class, it is known as method overriding.

Here, the viewDidLoad in the superclass (UIViewController) is only an empty function. You need to Just override the function for your initial setup of the view once it has been loaded.

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