All photos contain what is called metadata. Depending on your camera the metadata can include location info, in fact most newer cameras do include location and the iPhones certainly do, so yes your friends can see the location. There are ways of removing some or most of the metadata but none with a simple iPhone or iPad that I know of. You would have to resort to other programs or Apps. I can remove most of the metadata using Windows, likely the same with a Mac. In Windows right click on the picture, select Properties, Details, and at bottom select Remove Properties and Personal Information, and remove all.