Quick Answer: What Is IB In IBOutlet?

Why is IBOutlet weak?

In Mac development an IBOutlet is usually a weak reference: if you have a subclass of NSViewController only the top-level view will be retained and when you dealloc the controller all its subviews and outlets are freed automatically.

UiViewController use Key Value Coding to set the outlets using strong references..

What is AppDelegate in Swift?

The two source code files are AppDelegate. swift and ViewController. swift. In iOS, a delegate is a class that does something on behalf of another class, and the AppDelegate is a place to handle special UIApplication states. It has a bunch of functions called by iOS.

How do you declare an IBOutlet property?

If you have a property defined that you want to make accessible to your storyboards, just add the @IBOutlet attribute before your property. Similarly with @IBAction to connect storyboard actions back to code. class MyViewController: UIViewController { @IBOutlet weak var likeButton: UIButton?

Which method of AppDelegate is called first?

I need to perform some what actions before Main. storyboard is be loaded and the controller will call method viewDidLoad . Now it turns out that method viewDidLoad in controller called before then application:did(will)FinishLaunchingWithOptions in AppDelegate .

What is an IBOutlet in Swift?

The IBOutlet attribute tells Xcode that you can connect to the nameTextField property from Interface Builder (which is why the attribute has the IB prefix). The weak keyword indicates that the reference does not prevent the system from deallocating the referenced object.

What is a storyboard in iOS?

A storyboard is a visual representation of the user interface of an iOS application, showing screens of content and the connections between those screens. In addition, a storyboard enables you to connect a view to its controller object, and to manage the transfer of data between view controllers. …

What is weak in Swift?

A weak reference is just a pointer to an object that doesn’t protect the object from being deallocated by ARC. In Swift, all weak references are non-constant Optionals (think var vs. … let ) because the reference can and will be mutated to nil when there is no longer anything holding a strong reference to it.

What is ViewController in Swift?

A view controller manages a single root view, which may itself contain any number of subviews. User interactions with that view hierarchy are handled by your view controller, which coordinates with other objects of your app as needed. Every app has at least one view controller whose content fills the main window.

What is a UIViewController?

A UIViewController is an object which manages the view hierarchy of the UIKit application. The UIViewController defines the shared behavior and properties for all types of ViewController that are used in the iOS application. The UIViewController class inherits the UIResponder class.

What is NIB in iOS?

A nib file is a special type of resource file that you use to store the user interfaces of iOS and Mac apps. A nib file is an Interface Builder document. … In effect, as you edit an Interface Builder document, you create an object graph that is then archived when you save the file.

What is storyboard entry point?

Instead of referencing specific view controllers, storyboard references can simply refer to the initial scene in a storyboard. … Use the Attributes Inspector to check Is Initial View Controller; this indicates this scene should be the entry point for the storyboard.

What is strong reference in Swift?

Strong Reference Cycle. In essence, strong references are used to describe the relationship between objects. When an object has a strong reference to another object, this creates a retain cycle that prevents the object that is being referenced from being deallocated and increases the retain count to 1.

What is retain count in Swift?

Retain Count represents number of owners for a particular object. It is zero till object does not have any owners. Increase in one ownership claim will cause retain count to increase by 1 and decrease will cause it to decrement by 1. Example: – Class A object is created using alloc/init and retain count is 1.

Is AppDelegate a singleton?

3 Answers. AppDelegate is however a singleton class but you show only use it for declaring things that applies globally in your application. … So if you want to create a variable that can be changed from multiple View controllers you should create a singleton class and declare that variable in that class.

Which of the Among class is super class of view controller objects?

UIViewController classOverview. The UIViewController class defines the shared behavior that is common to all view controllers. You rarely create instances of the UIViewController class directly. Instead, you subclass UIViewController and add the methods and properties needed to manage the view controller’s view hierarchy.

What does IBOutlet mean?

variable declarationIBOutlet is a keyword which is added to a variable declaration. It’s an indicator. It does not affect the declaration in any way. However, when the Interface Builder sees it, it will allows a programmer to set this variable through the “outlet” mechanism inside Interface Builder.

What is IBOutlet and IBAction in Swift?

@IBAction is similar to @IBOutlet , but goes the other way: @IBOutlet is a way of connecting code to storyboard layouts, and @IBAction is a way of making storyboard layouts trigger code. This method takes one parameter, called sender . It’s of type UIButton because we know that’s what will be calling the method.

Is SwiftUI better than storyboard?

We no longer have to argue about programmatic or storyboard-based design, because SwiftUI gives us both at the same time. We no longer have to worry about creating source control problems when committing user interface work, because code is much easier to read and manage than storyboard XML.

How does model view controller work?

MVC is popular as it isolates the application logic from the user interface layer and supports separation of concerns. Here the Controller receives all requests for the application and then works with the Model to prepare any data needed by the View.

Why outlets are weak in Swift?

weak is used because in most situations the owner of the outlet isn’t the same as the owner of the view. For example, a view controller doesn’t own someLabel – the view controller’s view does. var because outlets are, by definition, set after initialization.

What is UIWindow in Swift?

The backdrop for your app’s user interface and the object that dispatches events to your views.