UIScrollView contentSize Issue - With example code

Within my view I create a scrollview with a width of 320 and a height of 70.

Responding to the user touching a button, I expand the scrollview, so it is 380(h) x 320(w) in size.

The code for this is shown below:

CGRect scrollviewFrame = CGRectMake(0, 30, 320, 380);
[scrollView setFrame:scrollviewFrame];
[self layoutScrollImages:YES];
CGSize srect =  CGSizeMake([scrollView bounds].size.width, (kNumImages * (kScrollObjHeight + 10)));
[scrollView setContentSize:srect];

The constants mentioned in the above snippet are defined as:

const CGFloat kScrollObjHeight  = 80;
const NSUInteger kNumImages     = 100;

As I debug this project, I can see that srect is 320 (w) x 8000 (h) in size; however my issue is the scrollable area (where the user can actually touch to scroll the scrollview) remains the same as when it was it's original size.

I'm obviously missing something, does anyone know what it is?

have created a sam开发者_开发技巧ple project to illustrate the issue I am having, it is available here: http://dl.dropbox.com/u/9930498/ScrollViewTest.zip

The problem in your sample is you have a very odd structure for loading your views. As such the view you're adding to the DetailScrollView instance is the root view of the DetailScrollView.xib, not the scrollview itself, which I believe is what you were expecting.

Fastest way to fix your problem is to adjust the root view in DetailScrollView.xib to autoresize width and height.

A UIView cannot respond to touches that are outside of the bounds of its superview. In your example, it appears that you expand the scroll view, but the scroll view's parent is still only 100 units high.

You should imagine the scrollView as a window, where by the window I mean the frame of the scrollView, which is also the coordinates that the scrollView detects your touches. By setting the contentView as 320 (w) x 8000 (h) you only change the content of the scroll view, which is the complete area behind that window.

By expanding content view, the scrollView can scroll a broader area, but in order to detect touches in a bigger rect, you should change frame of the scroll view.