How could I initialize the @State variable in the init function in SwiftUI?

Question

Let's see the simple source code:

import SwiftUI  struct MyView: View {     @State var mapState: Int          init(inputMapState: Int)     {         mapState = inputMapState //Error: 'self' used before all stored properties are initialized     } //Error: Return from initializer without initializing all stored properties          var body: some View {         Text("Hello World!")     } } 

I need the init function here because I want to do some data loading here, but there is one problem, the @State variable could not be initialize here! How could I do with that? Maybe it's a very simple question, but I don't know how to do. Thanks very much!

Answer 1

Property wrappers are generating some code for you. What you need to know is the actual generated stored property is of the type of the wrapper, hence you need to use its constructors, and it is prefixed with a _. In your case this means var _mapState: State<Int>, so following your example:

import SwiftUI  struct MyView: View {     @State var mapState: Int      init(inputMapState: Int)     {         _mapState = /*State<Int>*/.init(initialValue: inputMapState)     }      var body: some View {         Text("Hello World!")     } }