I'm trying to execute an action every time a textField
's value is changed.
@Published var value: String = ""
var body: some View {
$value.sink { (val) in
print(val)
}
return TextField($value)
}
But I get below error.
Cannot convert value of type 'Published' to expected argument type 'Binding'
A prompt is the label in a text field that informs the user about the kind of content the text field expects. In a default TextField it disappears when the user starts typing, hiding this important information.
This should be a non-fragile way of doing it:
class MyData: ObservableObject {
var value: String = "" {
willSet(newValue) {
print(newValue)
}
}
}
struct ContentView: View {
@ObservedObject var data = MyData()
var body: some View {
TextField("Input:", text: $data.value)
}
}
In your code, $value
is a publisher, while TextField
requires a binding. While you can change from @Published
to @State
or even @Binding
, that can't observe the event when the value is changed.
It seems like there is no way to observe a binding.
An alternative is to use ObservableObject
to wrap your value type, then observe the publisher ($value
).
class MyValue: ObservableObject {
@Published var value: String = ""
init() {
$value.sink { ... }
}
}
Then in your view, you have have the binding $viewModel.value
.
struct ContentView: View {
@ObservedObject var viewModel = MyValue()
var body: some View {
TextField($viewModel.value)
}
}
I don't use combine for this. This it's working for me:
TextField("write your answer here...",
text: Binding(
get: {
return self.query
},
set: { (newValue) in
self.fetch(query: newValue) // any action you need
return self.query = newValue
}
)
)
I have to say it's not my idea, I read it in this blog: SwiftUI binding: A very simple trick
If you want to observe value
then it should be a State
@State var value: String = ""
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