iPhone Dev Resources
Display long texts in a UIScrollView
In some applications I've ran into a bug where rendering a view as a subclass of a scroll view would cause weird effects on the screen. After scrolling a certain amount rendering fails and 'undefined behavior' occurs. I've come across this problem during development of my own applications but also in other applications like the iPhone App Store app for example.
The problem is caused by views that exceed 1024 pixels in height. From the UIImage documentation:
You should avoid creating UIImage objects that are greater than 1024 x 1024 in size.
Besides the large amount of memory such an image would consume, you may run into problems
when using the image as a texture in OpenGL ES or when drawing the image to a view or layer.
Create a view of 1024 x 1025 pixels and the rendering behaviour is 'undefined'. Because the iPhone screen is only 320 pixels in width, in general views are accepted that are taller. The problem usually appears when using views that exceed 2000 pixels in height. (2009 pixels actually according to the tableView:heightForRowAtIndexPath: documentation) Scrolling to a point beyond this height will again result in the 'undefined' rendering behaviour.
Take a look at the iPhone App Store app. The info for each application displays a header followed by a description and some screenshots. These are all separate views as subview of a scroll view. The complete description is rendered using a single text view. For most application this solution is sufficient. Some application however have a very long application description which results in a textview that exceeds the 2000 pixels.
The solution
If you don't know how much text you are going to display beforehand, or the you are already sure you're text will be very long, don't use a single textview (or a single UITableViewCell). Split the text into multiple parts and render the text using multiple views that do not exceed 1024 in height.