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.
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>
.
2. Create a slider with a new binding variable
In this step, we are creating a Binding variable. A Binding variable is a computed property. By creating it as the value that the slider is using, we can utilize the setter
to call the function every time the value is changing.
3. Create the function to call when the slider changes value
Make sure to make the function that you need to call when the slider changes values.
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Top comments (4)
Hello, I have a question:
How can I detect, when the user moves the slider if the value is incrementing or decrementing?
If the user moves up the slider I need to call a method (for instance: volume up)
If the user moves down the slider I need to call a method (for instance: volume down)
thanks!
Here the answer
forums.swift.org/t/how-can-i-detec...
Helped me a lot, but in "set:" it should be called either newVal or newValue.
Thanks for catching that! I'll update the post :)