See below playground code:
import SwiftUI
import PlaygroundSupport
struct InnerView: View {
@Binding var text: String
@State private var startedChange = false
var body: some View {
Text("Hello").onAppear {
if !self.startedChange {
DispatchQueue.main.asyncAfter(deadline: .now() + 1.0) {
self.text = "cat"
}
DispatchQueue.main.asyncAfter(deadline: .now() + 2.0) {
self.text = "cheetah"
}
self.startedChange = true
}
}
}
}
struct ContentView: View {
@State private var animalName = "dog"
var body: some View {
VStack {
InnerView(text: $animalName)
Text(animalName)
}
}
}
PlaygroundPage.current.setLiveView(ContentView())
The bottom Text(animal.name)
alternates irregularly between "cat" and "cheetah," in an infinite loop of race conditions. I expected the text to change to "cat" after one second and then "cheetah" after another.
I would not have expected
@State private var startedChange = false
to be initialized more than once.
Where is my mental model wrong?
(Xcode 12.0)
chrisguthrie
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Hi all!When presenting a specific modal sheet in a SwiftUI project, I consistently get a ton of console output like:=== AttributeGraph: cycle detected through attribute 290 ===Like, a couple hundred of these logs. It appears to be accompanied by a stutter/slowdown in the UI, but there's no crash and everything looks to be in the right place.Is the "cycle" here some sort of ARC retain cycle? Is it SwiftUI-specific? (I'm asking here because I've never seen this warning in a classic UIKit project.) Where can I go to learn more about this?Thanks!