UITextView scrolling is unreliable when contained in a zoomed-in scroll view

Originator:steipete
Number:rdar://21180966 Date Originated:01-Jun-2015 01:08 PM
Status:Open Resolved:
Product:iOS Product Version:iOS 8.3
Classification:UI/Usability Reproducible:Always
 
Summary:
When an UITextView instance is nested inside larger scrollable UIScrollView that is also zoomed in (zoomScale > 1), the text view doesn’t reliably scroll. Most of the time the parent scroll view grabs the pan gesture and it is scrolled instead. This is not an issue at zoomScale = 1.  

Steps to Reproduce:
Extract the attached archive. Take a look at the included view that show shows the issue. Open the provided example project and follow the on-screen instructions. You might need to try this a few times, but usually it’s simple to reproduce on the device (see video). 

Expected Results:
UITextView scrolling would be prioritized over the parent scroll view. 

Actual Results:
Most of the time the parent scroll view scrolls instead of the text view (but not always). 

Regression:
iOS 8.3, iPhone and iPad (a bit harder to reproduce on the simulator, but also observable)

Notes:
This cause issues in PSPDFKit forms. Also tested with iOS 8.4b3, same result.

Comments


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