Open Radar

 
Summary:
I've just tested this with UIDatePicker, but I presume that the bug affects UIPickerView in general.

When you have a long, infinite or cyclical list of values in a UIPickerView such as the date (infinite), hour and minute (cyclical) in a UIDatePicker, you can scroll fast enough for the picker view to reach an acceleration which it breaks.

I've found that for the date (so presumably for infinite lists), the picker view breaks by having a strange superposition of various dates (see screenshot). Whenever the picker view is "broken," moving to a date that's supposed to be one day away actually changes the date by several years.

For the time (so presumably for cyclical lists), the picker view breaks by preventing the values to loop (cycle). (see screenshot)

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Another related bug happens in the reminders app after a reminder with an alarm way in the future gets saved. For me, the year 2088 got converted to a year in the 20th century after saving.

Steps to Reproduce:
1) Go to Reminders app.
2) Create reminder.
3) Attempt to set the alarm to a date, way, way in the future. Like the year 2080.

Expected Results:
The UIPickerView will show valid values and continue working as expected.

Actual Results:
The UIPickerView breaks in strange ways, as described in the "description" section.

Version:
iOS 9.1

Notes:
My guess is that the scrolling is going so fast that the call to viewForRow on UIPickerView can't keep up.  Although that'd mean that even though each row isn't rendering each row is being dequeued.

Configuration:
iPhone 6 64GB