SwiftUI how add custom modifier with callback - ios

Question

In SwiftUI you can wrote code like this:
List {
ForEach(users, id: \.self) { user in
Text(user)
}
.onDelete(perform: delete)
}
I try to add functionality with .onDelete syntax method to my custom component:
struct MyComponen: View {
#Binding var alert: String
.
.
.
}
I try to add this ability with extension:
extension MyComponent {
func foo() -> Self {
var copy = self
copy.alert = "Hohoho"
return copy
}
func onDelete() -> Void {
}
}
How can I change state (or callback function with):
struct ContentView: View {
var body: some View {
Group {
MyComponent() //-> with alert = "state 1"
MyComponent().foo() //-> with alert = "state 2"
MyComponent().foo(action: actionFunction) //-> how do this?
}
}
}

Answer 1

Continuing your approach this might look like below. As alternate it is possible to use ViewModifier protocol.
struct MyComponen: View {
#Binding var alert: String
var action: (() -> Void)?
var body: some View {
VStack {
Text("Alert: \(alert)")
if nil != action {
Button(action: action!) {
Text("Action")
}
}
}
}
}
extension MyComponen {
func foo(perform action: #escaping () -> Void ) -> Self {
var copy = self
copy.action = action
return copy
}
}
struct TestCustomModifier: View {
#State var message = "state 2"
var body: some View {
VStack {
MyComponen(alert: .constant("state 1"))
MyComponen(alert: $message).foo(perform: {
print(">> got action")
})
}
}
}
struct TestCustomModifier_Previews: PreviewProvider {
static var previews: some View {
TestCustomModifier()
}
}