iPhone UIScrollView, Slow down the scrolling

Question

How do I add some extra drag to the UIScrollView physics. It scrolls just a little too fast for what I am doing. (I don't want to disable altogether, I still like the rubber band effect when you get to the end or beginning of the view.) Is there any way to slow it down?

Answer 1

This is simply not possible right now. Maybe Apple will one day extend the API to allow it, but until that day, you're stuck with the default speed.

The only other option would be your own scrolling implementation. This isn't trivial if you want all the nice polish such as the rubber band effect and the way the scrolling will lock horizontally or vertically. Not to mention flicking to scroll.

Also, Apple has a patent for some of those scrolling behaviours, so writing your own might even be dangerous. Source: "Apple's touch-screen patent".

A computing device, comprising: a touch screen display; one or more processors; memory; and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including: instructions for detecting one or more finger contacts with the touch screen display; instructions for applying one or more heuristics to the one or more finger contacts to determine a command for the device; and instructions for processing the command; wherein the one or more heuristics comprise: a vertical screen scrolling heuristic for determining that the one or more finger contacts correspond to a one-dimensional vertical screen scrolling command rather than a two-dimensional screen translation command based on an angle of initial movement of a finger contact with respect to the touch screen display; a two-dimensional screen translation heuristic for determining that the one or more finger contacts correspond to the two-dimensional screen translation command rather than the one-dimensional vertical screen scrolling command based on the angle of initial movement of the finger contact with respect to the touch screen display; and a next item heuristic for determining that the one or more finger contacts correspond to a command to transition from displaying a respective item in a set of items to displaying a next item in the set of items.

But of course, I am not a lawyer.

Answer 2

Actually, after reading the Documentation I discovered the property for UIScrollView that slows down the scrolling, so Apple does make this readily available for anyone else looking for this:

scrollView.decelerationRate = UIScrollViewDecelerationRateFast;

Even though it says fast, it is speeding up deceleration which in effect slows the scrolling down. This was exactly what I needed. And no worry of patents. :)

Answer 3

Actually you can make block animation with ScrollToRowAtIndexPath:... with animated set to NO. This way block animation will animate underlaying variables manually using selected time.