[SR-13576] UIDatePicker crashes app when enabling/disabling 24-hour time multiple times

[swift-ci]

Previous ID	SR-13576
Radar	rdar://problem/69308996
Original Reporter	tassiomm (JIRA User)
Type	Bug

Environment

**XCode Version:** 11.3.1 **Device:** iPhone 6s Plus **Device iOS Version:** 13.6 Xcode Project: **Swift 5** **Target:** iOS 13.2

Additional Detail from JIRA

| | | |------------------|-----------------| |Votes | 0 | |Component/s | Standard Library | |Labels | Bug | |Assignee | None | |Priority | Medium | md5: a3245dac2c3ee77de8e819d6cd8bd781

Issue Description:

UIDatePicker will crash if user switches 24-hour time multiple times and opening the app between switches.

Reproducible test case:

Create a new Single View App Project in Swift. Go to ViewController that XCode already created and paste the code:

 import UIKit
 class ViewController: UIViewController {
     private var someDatePicker = UIDatePicker()
 }

Steps:

• Before running the app make sure Settings > General > Date & Time > 24-Hour Time is enabled.
• Run the app
• Close the app (do NOT kill it)
• Switch 24-Hour Time toggle
• Open the app again
• Repeat the last 3 steps 3 Times
• The app will crash and the console output should print the following exception:

  -[__NSArrayM objectAtIndex:]: index 3 beyond bounds [0 .. 2]

[typesanitizer]

@swift-ci create

[swift-ci]

Comment by Tassio Moreira Marques (JIRA)

Note: For reference, setting the calendar prevents the bug from happening:

someDatePicker.calendar = Calendar(identifier: .gregorian)

[AnthonyLatsis]

This sounds very much like an issue with UIKit (not the compiler or Standard Library). @tassiomm Assuming you are the author, please use the feedback assistant for these sorts of SDK bugs.