SwiftUI: View flashes briefly white [duplicate] - swift

Question

This question already has answers here:
How to prevent initial white flash when showing a UIWebView?
(4 answers)
Closed 2 years ago.
I'm a beginner SwiftUI programmer and I'm encountering the following problem:
I have two Views, one loading view (Rectangle) and one web view (WKWebView).
Using those two views like this:
var body : some View {
ZStack {
WebView(self.webView)
Rectangle()
.foregroundColor(self.state.isLoading ? self.loadingColor : Color.clear)
}
.onAppear {
// Initialize web view etc.
// Sets self.state.isLoading to false after some time has passed
}
}
Interestingly when self.state.isLoading changes from true to false the UI briefly flashes white.
I don't know why this is happening, especially because the WebView definitely isn't white at the point of showing.
I tried adding a background rectangle and setting the backgroundColor of self.webView and self.webView.scrollView:
var body : some View {
ZStack {
Rectangle()
.foregroundColor(Color.red)
WebView(self.webView)
Rectangle()
.foregroundColor(self.state.isLoading ? self.loadingColor : Color.clear)
}
.onAppear {
// Initialize web view etc.
self.webView.backgroundColor = UIColor.red
self.webView.scrollView.backgroundColor = UIColor.red
// Sets self.state.isLoading to false after some time has passed
}
}
I expected to see a brief red screen, but it remains white.
Adding an animation to the Rectangle() transition makes the flashing go away
Rectangle()
.foregroundColor(self.state.isLoading ? self.loadingColor : Color.clear)
.animation(.easeIn)
Am I missing something or doing something wrong?

Answer 1

I'm thinking this may have something to do with the self.state.isLoading variable and when it changes, the whole view is reloading. Can you try instead making the isLoading a local variable in the struct (#State var isLoading: Bool = false) and then toggling the local variable instead?