Once precise location is enabled on your device, compose a Post as you normally would. If you haven't previously attached a location to your Posts, you may see a prompt asking if you’d like to enable precise location.
Tap the location icon in the Post compose box to open a list of places that you can choose.
Select the location you want to add to your Post.
If you’re attaching a photo to your Post that was taken on the in-app camera and tap the location icon, your precise location (latitude and longitude) will be associated with the Post and findable via API.
For earlier versions of X for iOS, your Post will always contain both your selected location name and the precise location of your device (which can be found via API) when you Post.
The next time you Post using the X app on the same device, your general location will automatically be displayed with your Post, using your current location. For X for iOS versions before 6.26, your precise location will automatically be attached to the Post (and findable through API) along with the general location.