Switching apple ids

Devices are not meant to switch back and forth like that. Ideally you would erase the device entirely between accounts. When you sign into the new account you would be asked if you wish to merge the old data currently on the phone into the new account or delete the information currently on the phone. Then the same would happen when you switch back. People do this unintentionally and end up having to spend a lot of time cleaning stuff from other accounts out of their account. It can also be a security risk if you do not trust the other user.

I would recommend making sure your device is fully backed up, then erase it for the other account.

Also, I hope the other user is somebody you trust a lot. While they are signed into your iPhone they now become the owner of the device. If they forget to sign out you may permanently lost access to the device.

See

What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support

Edit: Also take note of this: See and remove your devices that are associated with Apple ID purchases - View and remove your devices that are associated with Apple ID purchases - Apple Support - Read "More about associated devices" at the end where it refers to the 90 day wait. This applies to re-downloading past purchases (you can make new purchases), automatic downloads, and iCloud based services such as Family Sharing, Match, and Apple Music.

haq5371 wrote:

if i wanted to switch apple ids for a few days on my phone would i lose all the data currently in my phone or would it stay?

No. Switching Apple IDs does not erase data on its own. Also all apps will remain tied to the Apple ID that downloaded them and will require it to update.

and would i be able to switch back to the original apple id with no problems?

No. Depending on what you do after switching Apple IDs it may cause the Apple ID to become associated with the device which would lock the previous one out for 90 days.

click here ➜ View and remove your devices that are associated with Apple ID purchases - Apple Support

Unless there is a very, very good reason to do this, it should be avoided.