Be transparent. Tell the user that you are collecting data, explain what you are collecting, and give them the option to refuse.
Currently, there is a lot of talk about address books and photos being uploaded without user consent. You want your users to understand what you collect and that you respect them and their personal data.
You might want to take a look at Localytics. Their library is open source, so you can see what data is collected, and you can enable logging to find out what will be downloaded. Using their services will not allow you to configure your own server.
tagEvent: it would be useful to collect where users spend their time, probably there is no need to go to a paid plan.
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