When implementing a UISlider, it is a good idea to consider how much the slider value should change when swiping up/down to adjust it. It might not always make sense to do it in 10% increments, which is the default behaviour.

A slider to adjust value from 0 to 40 miles. By default the increment values will be: 4 miles, 8 miles, etc. But you can change it so it goes on steps of 5 miles by adjusting the value as desired overriding accessibilityIncrement and accessibilityDecrement. So the increment values are: 5 miles, 10 miles, etc.

Could be because the value at those intervals doesn't make sense, or feel random, or because it wouldn't provide the user with a fine enough control being able to go through the whole slider in just 10 swipes.

It user will still be able to adjust the slider to any value by double tapping and holding and then moving the finger left or right, bypassing VoiceOver gestures. VoiceOver announces the new value as it changes.