programming that can connect accelerometer to nRF Connect on iphone

You need to edit your Original Post because you appear to be using BLE to connect to your phone and not an nRF24L01+. You cannot communicate with a phone with an nRF24.

And, sorry, I am not familiar with BLE.

To make it easier for people to help you please also modify your post and use the code button </> so your code looks like this and is easy to copy to a text editor. See How to use the Forum

...R