How to stop recreating #state variable after recreating view in SwiftUI - ios

Question

#State var myDict: [String: Double] = [:]
var body: some View {
HStack(alignment: .top) {
Button(action: {
self.myDict[self.tag ?? ""] = amountValue
})
}
}
I have two user, when i select 1st user I add value to myDict, and when I select 2nd user I want to add another value to it (means myDict will have 2 object), but when i select 2nd user #state variable is refresh and have only one value of 2nd user. (means myDict have 1 object)
is there any way so that I can have both the value in dict not only one?

Answer 1

actually, this can happen that for both users self.tag is nil and ("") is used as a key for the dictionary
self.myDict[self.tag ?? ""] = amountValue
and if this happens you may want to make sure that self.tag is not nil
I have created a test environment just like your case but I have
import SwiftUI
struct swiftUIDoubt1: View {
#State var myDict: [String: Double] = [:]
var body: some View {
VStack{
Button(action: {
myDict["Hello, World!"] = 9.99999
print(myDict)
}, label: {
Text("\(myDict["Hello, World!"] ?? 0)")
.padding()
})
Button(action: {
myDict["bye, World!"] = 1.11111
print(myDict)
}, label: {
Text("\(myDict["bye, World!"] ?? 0)")
.padding()
})
}
.onAppear(perform: {
print(myDict)
})
}
}
now as you can see when my screen will appear my dictionary should be empty and an empty dictionary must be printed, as you can see in the image
console log when the app is first opened
when I click first button single item will be added and you can see in console log
and when I will click on the second button you can see I have two different items in my dictionary
let success = "two different items has been added to dictionary"
as #state variable to managed by swift UI and will not change with ui update

Answer 2

Small example : The add in the subview update the dictionnaire for the desired user in parent view
import SwiftUI
struct UpdateUsersDict: View {
#State var myDict: [String: Double] = [:]
#State var amount: Double = 100
var body: some View {
VStack {
HStack {
OneUserView(myDict: $myDict, amount: amount, tag: "user 1")
OneUserView(myDict: $myDict, amount: amount, tag: "user 2")
OneUserView(myDict: $myDict, amount: amount, tag: "user 3")
}
HStack {
Text("\(myDict["user 1"] ?? -1)")
Text("\(myDict["user 2"] ?? -1)")
Text("\(myDict["user 3"] ?? -1)")
}
}
}
}
struct OneUserView: View {
#Binding var myDict: [String: Double]
#State var amount: Double
var tag: String
var body: some View {
HStack(alignment: .top) {
Button(tag, action: {
self.myDict[self.tag] = amount
})
}
}
}
struct UpdateUserDict_Previews: PreviewProvider {
static var previews: some View {
UpdateUsersDict()
}
}