Programmatically scroll a UIScrollView

If you want control over the duration and style of the animation, you can do:

[UIView animateWithDuration:2.0f delay:0 options:UIViewAnimationOptionCurveLinear animations:^{
    scrollView.contentOffset = CGPointMake(x, y);
} completion:NULL];

Adjust the duration (2.0f) and options (UIViewAnimationOptionCurveLinear) to taste!

You can scroll to some point in a scroll view with one of the following statements in Objective-C

[scrollView setContentOffset:CGPointMake(x, y) animated:YES];

or Swift

scrollView.setContentOffset(CGPoint(x: x, y: y), animated: true)

See the guide "Scrolling the Scroll View Content" from Apple as well.

To do slideshows with UIScrollView, you arrange all images in the scroll view, set up a repeated timer, then -setContentOffset:animated: when the timer fires.

But a more efficient approach is to use 2 image views and swap them using transitions or simply switching places when the timer fires. See iPhone Image slideshow for details.