SwiftUI Tutorial: State and Binding

Understanding how State and Binding works

Figure 1.

As a general idea, state and binding are property wrappers that deals with reading and writing a value. It is an important core concept for creating an app in SwiftUI.

This tutorial is part of my SwiftUI Tutorial series.

What is State?

In Swift language, modification of values inside a struct is not allowed (immutable) because it is considered as type of value. Example, I have this declared variable inside a struct:

var isPlaying: Bool = false

The isPlaying being false cannot be modified to true when the program is running, as long as it is under a struct. The only way for it to be modified under a struct, is by moving the storage into a shared memory. This can be done by wrapping it with state property like this:

@State var isPlaying: Bool = false

Setup a New Project

To understand more about state, create a new project or open an exisiting one that you use for practice. You can refer to this link if you need a step-by-step process on how to do it.

Let’s create a player button that changes appearance every time the user taps.