To edit an Xcode generated XLIFF file online with POEditor, you need to be registered (it takes just a few seconds to open a free account) and to follow these steps.
Add a new project in your Dashboard.
Add a language to the project and then import your strings from the iOS XLIFF file, using the Import functionality in the project page.
Choose in the import options to 'Also import translations in...' the language you've just added, making sure to check the box to get translations from
This language will automatically be set as your project's Default Reference Language after you import the translations. You can change the DRL in the project's Settings.
If you have translations in the
<target>tag also and want to add them to the project, create a new language and import them there.
Add more languages to the project and manage their translation, with the optional help of contributors.
When you're done with the XLIFF language edit, use the Export button in any translation page to download a localized XLIFF file.
Note: Creating a first project launches a Free Trial, which increases the account's limit from 1000 strings to 30 000. When the trial period is over, the free account can still be used up to 1000 strings.