How to call a function when a slider changes in SwiftUI

There are times you might want to call a function when a slider changes in SwiftUI. I did this recently to send out the slider’s value to another device when the slider is moving. I couldn’t wait to send out the final value since that would be a delayed response for the user.

After the code example, I’ll explain the three steps. Click here for a Gist

import SwiftUI
struct SliderExample: View {
// 1. declare a state for the value of the slider
    @State private var value: Float = 0.0

// 2. create a slider with a new Binding variable
    var body: some View {
        Slider(value: Binding(
            get: {
                self.value
            },
            set: {(newValue) in
                  self.value = newValue
                  self.doSomething()
            }
        ))
    }

// 3. create the function to call when the slider changes value    
    func doSomething(){
        print("\(value)")
    }
}

1. Declare a state variable for the value of the slider

This is the variable that the slider is currently. It needs to be declared with a State property wrapper since the value is going to change. It also needs to have a Float type since a Slider needs a Binding<Float>.