how to record audio at distance?

It is not totally clear.

You want the second iPhoe to open recording on the first, automatically, without user of the first being involved ?

I don't think it is possible, that would be a serious security leak.

But you can notify user of the first iphone that you want to start recording ; if he accepts, you record.

It should be possible, if the user of iPhone 1 launches an app, connects to iphone2, to let iphone 2 start / stop recording.

But at some point, user 1 must be in the loop.

Thank for your help.

If I can explain more, I want to do the same thing as with the application "my friends" but with the microphone.

In my friends app, the user 1 allows the location and the user 2 can ask the position at any time.

In my case, the user 1 allows the microphone and the user 2 can record at any time.

How it works? Which architecture of communication use it?

It's using iCloud to communicate messages between devices.

Ok. Is it possible to transfert audio file in this message?

Can you explain in details Icloud communication, particulary the second part between icloud and user 1?

user 2 -> icloud -> user 1

User 1 check icloud all the time? How user 1 know that Icloud want to know his position?

It is a bit long to explain.

Here is a tutorial:

h ttps://www.raywenderlich.com/134694/cloudkit-tutorial-getting-started

Thank for the link.

Icloud works with database, ok.

But I don't understand how an action can be launch with database.

By action, I want to say "geolocalise user 1" with my exemple, or for my project "record an audio".