SwiftUI doesn't refresh until button action finishes - ios

Question

I want the view to be updated every time #State list gets updated.
But when I use Button to trigger a consecutive update, the list gets updated only after all the consecutive updates are finished.
This code updates the list 10 seconds after the button is pressed.
What should I do to make this code update every second?
#State var i_list: [Int] = []
var body: some View {
VStack {
Button(action: {
for i in 0..<10 {
i_list.append(i)
do {
sleep(1)
}
}
}) {
Text(button_text)
}
List (i_list, id: \.self){ i in
Text(String(i))
}
}
}
Solved:
I solved this problem by updating the list in a different thread.
let globalQueue = DispatchQueue.global()
globalQueue.async {
for i in 0..<10 {
DispatchQueue.main.async {
i_list.append(i)
}
do {
sleep(1)
}
}
}

Answer 1

If you want to see your view updates immediately, instead of using a for loop to update your array, use a publisher. Here I use a timer and add a onReceive(timer) on the List
struct ContentView : View {
#State var i_list: [Int] = []
#State var currentNumber = 0
let timer = Timer.publish(every: 1, on: .main, in: .common).autoconnect()
var body: some View {
VStack {
List (i_list, id: \.self) { i in
Text(String(i))
}.onReceive(timer) { _ in
guard currentNumber < 10 else {
return
}
i_list.append(currentNumber)
currentNumber += 1
}
}
}
}
Edit: changed currentNumber to #State