If you have a mobile app available on both iOS and Android platforms and you want to localize the strings in the same POEditor project, you can do that using iOS .strings and Android .xml files and by following the tips below.
1. Use the same keys for both iOS and Android
Because keys/string ids are imported as terms in POEditor and the uniqueness of a term is given by the term-context pair, you will need to use identical keys for both platforms if you want the strings in the source language to be imported just once.
2. Use the Tagging System
Tagging the keys on import allows you to keep the strings grouped by platform within the same localization project, and filter them during translation and on export.
This are especially handy if have some strings unique to iOS or Android.
3. Use different keys for source strings that should be translated differently
In case you have a source string which should be translated differently for each platform (iOS or Android), add it twice to the localization project, using different keys. This is necessary because it's not possible to have more than one translation for the same term in the same localization project.
4. Use placeholders common to both iOS and Android
If you're localizing iOS and Android strings in the same project, it's indicated to use variables common to both platforms, because it is not possible to convert the format of the placeholders on export.
If you can't use the same keys for both iOS and Android
When you can't use the same keys for both iOS and Android, it's best to create a separate project for each platform. If you have a paid account, you can use the Translation Memory after you translate the strings in one localization project to recycle the translations.