So I am new to IOS dev and Xcode but far from being a newbie in UI components in many other technologies. I am implementing a UISlider and investigated its API but could not find out how to:
1 + 2) Yes, there is no built-in snap functionality, but you can implement it yourself easily. Just catch the value-changed events of the slider, and update its value to the desired value. The action method for rounding the slider values can update a label displaying the value, too.
2 + 3) You must implement that by yourself. These features are very use case specific.
UIKit is rather than a set of small building blocks for general purposes.