ios - SwiftUI: How to get continuous updates from Slider

Question

I'm experimenting with SwiftUI and the Slider control like this:

struct MyView: View {

    @State private var value = 0.5

    var body: some View {
        Slider(value: $value) { pressed in
        }
    }
}

I'm trying to get continuous updates from the Slider as the user drags it, however it appears that it only updates the value at the end of the value change.

Anyone played with this? know how to get a SwiftUI Slider to issue a stream of value changes? Combine perhaps?

Answer 1

In SwiftUI, you can bind UI elements such as slider to properties in your data model and implement your business logic there.

For example, to get continuous slider updates:

import SwiftUI
import Combine

final class SliderData: BindableObject {

  let didChange = PassthroughSubject<SliderData,Never>()

  var sliderValue: Float = 0 {
    willSet {
      print(newValue)
      didChange.send(self)
    }
  }
}

struct ContentView : View {

  @EnvironmentObject var sliderData: SliderData

  var body: some View {
    Slider(value: $sliderData.sliderValue)
  }
}

Note that to have your scene use the data model object, you need to update your window.rootViewController to something like below inside SceneDelegate class, otherwise the app crashes.

window.rootViewController = UIHostingController(rootView: ContentView().environmentObject(SliderData()))