Changing UISlider exponentially - swift

Question

I am trying to create a slider where the value gets changed exponentially.
Let’s say the minimum is 0 and the maximum is 100. The first half of the slider should change the value slowly, like 0-10 and afterwards faster. I looked up different sites on StackOverflow but none really made sense to me. There seems to be math operations like pow() and exp(). Best would be to put it all in one function so i can use it for different parameters with a function that looks like this:
function(slidervalue, min, max, factor)
and returns the value.

Answer 1

i have managed to create these 2 functions to solve my problem:
func setParamLog(sliderValue: Float, min: Float, max: Float)->Float
{
// Output will be between minv and maxv
var minv :Float = log(min);
var maxv :Float = log(max);
// Adjustment factor
var scale :Float = (maxv - minv) / (max - min);
return exp(minv + (scale * (sliderValue - min)));
}
func setSliderLog(wpm: Float, min: Float, max: Float)->Float
{
// Output will be between minv and maxv
var minv :Float = log(min);
var maxv :Float = log(max);
// Adjustment factor
var scale :Float = (maxv - minv) / (max - min);
return (((log(wpm) - minv) / scale) + min);
}
it would be great to figure out now how i can adjust the scale factor

Answer 2

You could create a custom UISlider that wraps the functionality you want.
import Foundation
class ExponentialSlider {
...
var exponentialValue: Double {
get {
return exp(Double(self.value))
}
}
}
And then call it directly from the slider like this:
yourSlider.exponentialValue
You could also use the min and max values of the slider to modify the result of the computed property.

Answer 3

what i come up with yet is this function:
func exponentSliderValue(slidervalue: Float, exp: Float, min: Float, max: Float)->Float
{
var diff: Float = max - min
var result: Float = pow(slidervalue / diff, exp)
var endresult: Float = ((result * diff) + min) * 10
endresult.round()
endresult = endresult / 10
if(endresult >= min)
{
endresult = endresult + 0
}
if(endresult < min)
{
endresult = min
}
if(endresult >= max)
{
endresult = max
}
return endresult
}
it works pretty good. what i havent figured out yet is to do the whole thing in the opposite direction. all my sliders have default values.. so.. when i have a value of 40. it should translate to the right position (which is 1000) on the slider by default.. i have no idea yet how to do that. it would be great if someone can give me a hint. thanks