SwiftUI – Xcode not building when using the index variable of a ForEach loop - swift

I have a ForEach loop inside a TabView. Whenever I try to build the project using the index (for lack of a better word, here: slide) variable in a condition, it stalls and is not building; it's not showing any errors. If I'm using it interpolated, it works/builds.
TabView {
ForEach(1...3, id: \.self) { slide in
HStack {
if slide == 1 {
Text("Do something if slide is 1st slide") // doesn't work
}
Text("Test \(slide)") // works
}
.tag(slide)
}
}
Thanks for any tips!
Edit: Deleted case 2)
Edit: Added Tabview

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In the following code
struct ContentView: View {
#State private var cnt = 0
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ForEach in SwiftUI isn’t the same as a for loop. Your data needs to be identifiable for structural identity to work and you certainly should not be using indices. Either implement the Identifiable protocol or tell ForEach what key path is a unique ID (or is a getter that creates one from other properties) in the item struct. Don’t ever use id:\.self.
You can learn more about structural identity in the video WWDC 2021 Demystify SwiftUI

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Im trying to implement a feature in my app.
When I click on my picker:
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Tried the following:
If I correctly understood your scenario here is a possible approach (replication tested with Xcode 12 / iOS 14)
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By pressing the buttons you can change the value of playlistIndex correctly and the UI is refreshed.
On the contrary, the loop that prints each item of the playlist does not update which one is selected, and it is using the same variable playlistIndex
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ForEach does not refresh, because range was not changed - SwiftUI tries to optimise redrawing by checking for equality...
Use instead like below (if your playlist item Identifiable)
ForEach(Array(playlist.enumerated()), id: \.element) { (i, item) in
if i == self.playlistIndex {
Text("🔈 \(item.title)")
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Text(item.title)
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Why is my SwiftUI List row not always updating internally

I have a list of reminders grouped into sections by completion and date. With data coming from an ObservedObject DataStore called global. I pass a realmBinding to the cell. The cell can update this binding and it will trigger the data store to update.
List {
// Past Due
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Section(header: SectionHeader {}){
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GeneralReminderCell(reminder: reminder.realmBinding())
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}
}
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if self.global.completeReminders.count > 0 {
// Same as PastDue but for Completed
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}
The cell looks something like:
struct GeneralReminderCell: View {
#Binding var reminder:Reminder
var body: some View {
HStack(alignment:.top, spacing: 10) {
Image(systemName: reminder.completed ? "checkmark.circle.fill" : "circle")
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Text("Follow up with \(reminder.client.fullName)").fontWeight(.semibold)
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This behaviour almost always happens as expected, but sometimes the checked image will get out of sync with the completed state of reminder. I've look at this for quite some time and have not made much headway. Why is the checked image not always matching the state of the data?
Even though this is a very old question, I may have been working on what appears to be this same problem. In my case, my App is running on macOS. At first, the problem also seemed to be very intermittent and had been difficult to reproduce consistently.
I also have a View with a ForEach supplying rows to a List. My row's View contains an #State for an Optional Image that gets updated several different ways via actions performed by that same row View (e.g. Continuity Camera, file picker or drag & drop). The issue is that sometimes the new Image is shown and sometimes it is not shown. Using Self._printChanges() I am able to see that the #State is changing and the row's body it is being redrawn, however, the rendered View does not change. The only pattern that I am able to observe is that this issue only seems to occur with the last row in the List. Based on the success of my workaround below, it seems to confirm that there is an issue with the way SwiftUI's List reuses table cells.
My solution/workaround is to replace:
List {
ForEach {
}
}
With:
ScrollView {
LazyVStack {
ForEach {
}
}
}