I have a control that sets an @State variable to keep track of the selected tabs in a custom tab View. I can set the @State variable in code by setting the following:
@State var selectedTab: Int = 1
How do I set the initial value programmatically so that I can change the selected tab when the view is created?
I have tried the following:
1:
@State var selectedTab: Int = (parameter == true ? 1 : 2)
2:
init(default: Int) {
self.$selectedTab = default
}
Example of how I set initial state values in one of my views:
struct TodoListEdit: View {
var todoList: TodoList
@State var title = ""
@State var color = "None"
init(todoList: TodoList) {
self.todoList = todoList
self._title = State(initialValue: todoList.title ?? "")
self._color = State(initialValue: todoList.color ?? "None")
}
Joe Groff: "@State variables in SwiftUI should not be initialized from data you pass down through the initializer. The correct thing to do is to set your initial state values inline:"
@State var selectedTab: Int = 1
You should use a Binding to provide access to state that isn't local to your view.
@Binding var selectedTab: Int
Then you can initialise it from init and you can still pass it to child views.
Source: https://forums.swift.org/t/state-messing-with-initializer-flow/25276/3
This was so simple to solve once I discovered the answer!
You simply remove the initial value from the initialization by changing the declaration from:
@State var selectedTab: Int = 1
to:
@State var selectedTab: Int
and then the selectedTab variable automatically becomes a parameter in the instantiation statement. So the initialization would be:
TabBarContentView(selectedTab: 2)
Its that simple!!!!!
