Bug: Alarm offset must be positive on Android, but negative on iOS

[osartun]

When creating a calendar event with alarms the number of minutes must be different between iOS and Android or otherwise on one platform the alarm is before the startDate and on the other it's after the startDate.

iOS	Android

Also, the number is not allowed to be negative on Android or it might not show the alarms at all.

Environment

System:
    OS: macOS 10.15.7
    CPU: (8) x64 Intel(R) Core(TM) i7-4770HQ CPU @ 2.20GHz
    Memory: 350.89 MB / 16.00 GB
    Shell: 5.7.1 - /bin/zsh
  Binaries:
    Node: 12.14.1 - /var/folders/hp/wl2yw33n69xf_1lkp8y6gry80000gn/T/yarn--1605546136287-0.33153789553280055/node
    Yarn: 1.22.5 - /var/folders/hp/wl2yw33n69xf_1lkp8y6gry80000gn/T/yarn--1605546136287-0.33153789553280055/yarn
    npm: 6.13.4 - /usr/local/Cellar/nvm/0.33.11/versions/node/v12.14.1/bin/npm
    Watchman: 4.9.0 - /usr/local/bin/watchman
  SDKs:
    iOS SDK:
      Platforms: iOS 13.7, DriverKit 19.0, macOS 10.15, tvOS 13.4, watchOS 6.2
    Android SDK: Not Found
  IDEs:
    Android Studio: 3.5 AI-191.8026.42.35.5900203
    Xcode: 11.7/11E801a - /usr/bin/xcodebuild
  Languages:
    Java: 11.0.7 - /usr/bin/javac
    Python: 3.6.4 - /Users/oliver/.pyenv/shims/python
  npmPackages:
    @react-native-community/cli: Not Found
    react: 16.11.0 => 16.11.0
    react-native: 0.62.2 => 0.62.2
  npmGlobalPackages:
    *react-native*: Not Found

Steps to Reproduce

Sorry, this is an incomplete code sample.

RNCalendarEvents.saveEvent(title, {
  calendarId,
  description,
  notes: description,
  startDate: startDate.toISOString(),
  endDate: endDate.toISOString(),
  alarms: [{
    date: 30
  }],
});

Expected Behavior

I expect to get the same behavior on both, Android and iOS, when using the same data.

Actual Behavior

I get different results between Android and iOS.

Notes

I suggest to add Math.abs() to the Android code as CalendarContract.Reminders.MINUTES isn't allowed to be a negative value anyway (with the exception of -1).

react-native-calendar-events/android/src/main/java/com/calendarevents/RNCalendarEvents.java

Line 877 in 1bb027b

reminderValues.put(CalendarContract.Reminders.MINUTES, minutes);

[Aggie123]

Same problem here...

[MoOx]

Some people said that they were successfully using negative number.

Anyway, PR is welcome to improve the lib. This will be released as a major release even if that's a minor change because some people so iOS ? 30 : -30.

[gunnartorfis]

Same thing happening here.