So here is a little piece of code that sums up a problem I cannot figure out atm. In the code below I add and remove entries to a dictionary keyed by an Enum.
What I would expect is that every time I add an item a new random number is being generated in the Element view and displayed.
What happens is that for every same Ident the same random number shows up - event though the ForEach loop has had a state where that Ident key was not in the dictionary any more.
It appears as if ForEach does not purge the @State vars of the Element views that are not present any more, but reuses them when a new entry to the dictionary is added with the same Ident.
Is this expected behavior? What am I doing wrong? Here is the code:
import Foundation
import SwiftUI
enum Ident:Int, Comparable, CaseIterable {
case one=1, two, three, four
static func < (lhs: Ident, rhs: Ident) -> Bool {
lhs.rawValue < rhs.rawValue
}
}
extension Dictionary where Key == Ident,Value== String {
var asSortedArray:Array<(Ident,Value)> {
Array(self).sorted(by: { $0.key < $1.key })
}
var nextKey:Ident? {
if self.isEmpty {
return .one
}
else {
return Array(Set(Ident.allCases).subtracting(Set(self.keys))).sorted().first
}
}
}
struct ContentView: View {
@State var dictionary:[Ident:String] = [:]
var body: some View {
Form {
Section {
ForEach(dictionary.asSortedArray, id: \.0) { (ident, text) in
Element(dictionary: $dictionary, ident: ident, text: text)
}
}
Section {
Button(action: {
if let nextIdent = dictionary.nextKey {
dictionary[nextIdent] = "Something"
}
}, label: {
Text("Add one")
})
}
}
}
}
struct Element:View {
@Binding var dictionary:[Ident:String]
var ident:Ident
var text:String
@State var random:Int = Int.random(in: 0...1000)
var body: some View {
HStack {
Text(String(ident.rawValue))
Text(String(random))
Button(action: {
dictionary.removeValue(forKey: ident)
}, label: {
Text("Delete me.")
})
Spacer()
}
}
}