Top SwiftUI Interview Questions for 2023

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Steven Curtis

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Photo by Marten Bjork on Unsplash

Here is a set of top SwiftUI interview questions. If you would like to prepare yourself for an interview I suggest you use the following to give you that helping hand!

Basic SwiftUI Concepts

Views

  • Describe views in SwiftUI

A view in SwiftUI is a lightweight transient object designed to be thrown away when the source for it is changed.

That is SwiftUI has a data-driven nature and SwiftUI handles updates by recomputing the body of views where necessary in a performant manner. Developers don’t handle view refresh directly rather the system handles this.

SwiftUI views are struct under the hood and conform to SwiftUI’s View protocol in order to describe a user viewable element.

Components and Views

  • Describe the difference between @State, @Binding, @ObservedObject, @Published and @EnvironmentObject.

State

A property wrapper used to create a single source of truth for data in your app which mutates over time (and updating a view appropriately).

The wrappedValue in the state is anything (usually a value type). The wrappedValue is stored on the heap, and when it changes invalidates the View and views depending on this value are marked for update. Article

Binding

The @Binding property wrapper enables a two-way connection between a property which stores data and a view that displays and mutates that data.

The wappedValue is a value (anything) that is bound to something else. It gets/sets the value of the wrappedValue from some other source. When the bound-to value changes, it invalidates the view marking it for update. Article

ObservedObject and published

In order to make a property observable through @Published to classes outside the containing class, that containing class would need to inherit from ObservableObject, and the relevant property should be marked as @Published — which synthesizes an objectWillChange publisher to announce that the value will change. Article

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