I've included stubbed code samples. I'm not sure how to get this presentation to work. My expectation is that when the sheet presentation closure is evaluated, aDependency
should be non-nil. However, what is happening is that aDependency
is being treated as nil, and TheNextView
never gets put on screen.
How can I model this such that TheNextView
is shown? What am I missing here?
struct ADependency {}
struct AModel {
func buildDependencyForNextExperience() -> ADependency? {
return ADependency()
}
}
struct ATestView_PresentationOccursButNextViewNotShown: View {
@State private var aDependency: ADependency?
@State private var isPresenting = false
@State private var wantsPresent = false {
didSet {
aDependency = model.buildDependencyForNextExperience()
isPresenting = true
}
}
private let model = AModel()
var body: some View {
Text("Tap to present")
.onTapGesture {
wantsPresent = true
}
.sheet(isPresented: $isPresenting, content: {
if let dependency = aDependency {
// Never executed
TheNextView(aDependency: dependency)
}
})
}
}
struct TheNextView: View {
let aDependency: ADependency
init(aDependency: ADependency) {
self.aDependency = aDependency
}
var body: some View {
Text("Next Screen")
}
}
This is a common problem in iOS 14. The sheet(isPresented:)
gets evaluated on first render and then does not correctly update.
To get around this, you can use sheet(item:)
. The only catch is your item has to conform to Identifiable
.
The following version of your code works:
struct ADependency : Identifiable {
var id = UUID()
}
struct AModel {
func buildDependencyForNextExperience() -> ADependency? {
return ADependency()
}
}
struct ContentView: View {
@State private var aDependency: ADependency?
private let model = AModel()
var body: some View {
Text("Tap to present")
.onTapGesture {
aDependency = model.buildDependencyForNextExperience()
}
.sheet(item: $aDependency, content: { (item) in
TheNextView(aDependency: item)
})
}
}
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