What Is IBOutlet And IBAction In Swift?

What is unowned self in Swift?

The most common place you’ll see unowned variables is with closures that declare [unowned self] – this means “I want to reference self inside this closure but I don’t want to own it.” Why unowned rather than weak .

Both would work, but let’s face it: if self is nil inside a closure, something has gone wrong!.

Why outlets are weak Swift?

Because the outlet is declared weak, it is automatically set to nil when it’s deallocated. Because the outlet is an implicitly unwrapped optional, it has no value, that is, is equal to nil , and the application would crash as a result. If this happens, chances are you’re doing something you shouldn’t be doing.

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.

Where is the Storyboard in Xcode?

storyboard from the Project Navigator (on the left side of Xcode).

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.

How does IBAction connect to storyboard?

To connect a button to an action, hold down control while clicking and dragging from the button to the action you want to attach it to. In Swift 3, you’d like to change the @IBAction ‘s argument from default (_ sender: Any) to (_ sender: UIButton) or (_ sender: AnyObject) , but manually. It might work.

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 a sender in Swift?

The sender is the object that called the action. So let’s say if you have 2 UIButtons calling the same function buttonPressed .

Which property is used in IOS to set hint?

Use the hintFont property to assign a custom font or font size to the hint. By default, the hint uses the font of the text field. Use the hintColor property to change the color of the hint. By default, the hint uses the text color of the text field.

What is difference between weak and strong in Swift?

A strong reference means that you want to “own” the object you are referencing with this property/variable. In contrast, with a weak reference you signify that you don’t want to have control over the object’s lifetime. A weak reference is like observing the tree from afar. …

What is an IBOutlet?

The type qualifier IBOutlet is a tag applied to an property declaration so that the Interface Builder application can recognize the property as an outlet and synchronize the display and connection of it with Xcode. An outlet is declared as a weak reference ( weak ) to prevent strong reference cycles.

How do I declare an IBOutlet in Swift?

Simplicity rules in swift. 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?

What is 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.

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.

How do I create an outlet in Xcode 11?

Xcode indicates where you can insert an outlet declaration in your code. Release the Control-drag. The assistant editor displays a Connection menu. From this menu, choose Outlet, type the name of the outlet ( warriorButton in the screenshot below), and click Connect.

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.