What is class ViewController?

Overview. The UIViewController class defines the shared behavior that’s 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 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 ViewController iOS?

In iOS Development, a View Controller is responsible for displaying the data of our iOS application on the screen. It acts as an interface between its Views (created by the developer) and the application data. Each ViewController in the Storyboard is assigned a Class that inherits the UIViewController class.

What is a class Swift?

In Swift, you define a structure or class in a single file, and the external interface to that class or structure is automatically made available for other code to use. Note. An instance of a class is traditionally known as an object.

When loadView is called?

* If the view is not currently in memory, the view controller calls its loadView. method. 3. * The loadView method does one of the following: If you override this method, your implementation is. responsible for creating all necessary views and assigning a non-nil value to the view property.

What is Uitableview in Swift?

A view that presents data using rows in a single column.

What is the difference between View and ViewController?

A view controller is not drawable to the screen directly, it manages a group of view objects. View controllers usually have a single view with many subviews. The view controller manages the state of these views. A view controller is smart, and has knowledge of your application’s inner workings.

When should I use layoutSubviews?


The system calls this method whenever it needs to recalculate the frames of views, so you should override it when you want to set frames and specify positioning and sizing. However, you should never call this explicitly when your view hierarchy requires a layout refresh.

How do I add a ViewController?

Adding a second View Controller – YouTube

What is subclass in Swift?

Subclassing. Subclassing is the act of basing a new class on an existing class. The subclass inherits characteristics from the existing class, which you can then refine. You can also add new characteristics to the subclass.

What is class and struct in Swift?

In Swift, structs are value types whereas classes are reference types. When you copy a struct, you end up with two unique copies of the data. When you copy a class, you end up with two references to one instance of the data. It’s a crucial difference, and it affects your choice between classes or structs.

Is loadView called before viewDidLoad?

Use viewDidLoad( ), which is called AFTER loadView( ) has completed its job and the UIView is ready to be displayed. viewDidLoad( ) allows you to initialize properties of the view/viewController object and finalize them before viewWillAppear( ) is called.

What is ViewController life cycle?

The view controller lifecycle can be divided into two big phases: the view loading and the view lifecycle. The view controller creates its view the first time the view is accessed, loading it with all the data it requires. This process is the view loading.

What is the difference between UITableView and UICollectionView?

Tableiw is a simple list, which displays single-dimensional rows of data. It’s smooth because of cell reuse and other magic. 2. UICollectionView is the model for displaying multidimensional data .

How use TableView cell in Swift?

Create a Custom UITableViewCell with Swift

  1. Step 1: Create a new Cocoa Touch Class.
  2. Step 2: Designing the Cell.
  3. Step 3: Registering the new custom UITableViewCell with the UITableView.
  4. Step 4: Calling the registerTableViewCells method.
  5. Step 5: Updating the CellForRowAtIndexPath function.

How do I present a ViewController?

To present ViewController which works with XIB file you can use the following example:

  1. // Register Nib.
  2. let newViewController = NewViewController(nibName: “NewViewController”, bundle: nil)
  3. // Present View “Modally”
  4. self. present(newViewController, animated: true, completion: nil)

How do I link my storyboard to ViewController?

Create a new IBOutlet called shakeButton for your storyboard button in your ViewController. swift file. Select the shake button in Interface Builder. Then hold down the control button ( ⌃ ) and click-drag from the storyboard button into your ViewController.

How often is layoutSubviews called?

layoutSubviews is called when the view is created, but never again. My subviews are correctly laid out. If I toggle the in-call status bar off, the subview’s layoutSubviews is not called at all, even though the main view does animate its resize.

What triggers layoutSubviews?

The least expensive way to trigger a layoutSubviews call is calling setNeedsLayout on your view. This will indicate to the system that the view’s layout needs to be recalculated. setNeedsLayout executes and returns immediately and does not actually update views before returning.

How do I add a ViewController to a storyboard?

To add new ViewController once you have have an existing ViewController , follow below step:

  1. Click on background of Main. storyboard .
  2. Search and select ViewController from object library at the utility window.
  3. Drag and drop it in background to create a new ViewController .

What is Nsobject in Swift?

The root class of most Objective-C class hierarchies, from which subclasses inherit a basic interface to the runtime system and the ability to behave as Objective-C objects.

What is size classes in Swift?

Size classes help you change the layout of views to adapt to various screen sizes, ranging from a tiny iPhone SE to a massive 12.9” iPad Pro. There are 3 different cases for a size class: regular , compact , and unspecified .

Why struct is faster than class Swift?

So based on the above theory we can say that Struct is faster than Class because: To store class, Apple first finds memory in Heap, then maintain the extra field for RETAIN count. Also, store reference of Heap into Stack. So when it comes to access part, it has to process stack and heap.

Can we inherit struct in Swift?

A struct cannot inherit from another kind of struct, whereas classes can build on other classes. You can change the type of an object at runtime using typecasting. Structs cannot have inheritance, so have only one type. If you point two variables at the same struct, they have their own independent copy of the data.

Should I call super loadView?

You definitely should not be calling [super loadView] . I’d say you found a bug in the ZoomingPDFViewer example. You override loadView when you want to programatically create the view hierarchy for your view controller (not using a xib). As you pointed out, the docs clearly state that you should not call super.