How to properly animate UIScrollView contentOffset

Question

I have UIScrollView subclass. Its content is reusable - about 4 or 5 views are used to display hundreds of elements (while scrolling hidden objects reused and jumps to anoth

Answer 1

A nice way to do this is with the AnimationEngine library. It's a very small library: six files, with three more if you want damped spring behavior.

Behind the scenes it uses a CADisplayLink to run your animation block once every frame. You get a clean block-based syntax that's easy to use, and a bunch of interpolation and easing functions that save you time.

To animate contentOffset:

startOffset = scrollView.contentOffset;
endOffset = ..

// Constant speed looks good...
const CGFloat kTimelineAnimationSpeed = 300;
CGFloat timelineAnimationDuration = fabs(deltaToDesiredX) / kTimelineAnimationSpeed;

[INTUAnimationEngine animateWithDuration:timelineAnimationDuration
                                   delay:0
                                  easing:INTULinear
                              animations:^(CGFloat progress) {
                                    self.videoTimelineView.contentOffset = 
                                         INTUInterpolateCGPoint(startOffset, endOffset, progress);
                              }
                             completion:^(BOOL finished) {
                                   autoscrollEnabled = YES;
                             }];