UIScrollView and scrollRectToVisible

[SamB]

Hi. I'm having some trouble using scrollRectToVisible.

I have a quiz screen where the user can select an answer to a question. What I want to achieve is when the user gets the question right the scrollview should scroll to the next page.

I'm trying this:

// pageNumber is the current page

[scrollView scrollRectToVisbile:CGRectMake:(scrollView.frame.size.width * pageNumber + 1, 0, scrollView.frame.size.width, scrollView.frame.size.height)];

I managed to use the exact above to animate the scrollView when a user touches a certain area of the screen but cannot for the life of me work out how to use it when a user clicks the correct button.

In my viewDidLoad I set scrollView.contentSize

// numPages is the total number of pages

[scrollView setContentSize:CGSizeMake(scrollView.frame.size.width * numPages, scrollView.frame.size.height)];

Yet, when I try and call scrollRectToVisible when the user taps the correct answer and log the contentSize.width to the console, the console says that my contentSize.width value is zero. However, when I log the contentSize in viewDidLoad, the console output is the value I want.

I don't set the contentSize of the scrollView anywhere else so I can't understand how the content size is getting reset to zero.

Any help you can give me is much appreciated and I apologise for what is quite a long post for something that is probably very simple. Thanks.

[SamB]

Okay, I've established that if I use a button to scroll the scrollView then it works. So using scrollRectToVisible within an IBAction tied to a button works fine and logs the right contentSize of my scrollView. But, if I try and initiate the method from another method, the contentSize of the scrollView equals 0. Does anyone have any idea why that would be?

Thanks.

[Stokestack]

Make sure you're formatting your debugging string to the console for a float where you put the width; I had it set up as an int in the formatting string, and it always said zero for the width when in fact it was a perfectly valid floating-point number.