Can not install xcode 7 from store, stuck on app intall
You can also download an Xcode .dmg installer file directly from the apple developer site, downloads. Xcode 7.2 is no longer available, at time of writing Xcode 7.3 can be downloaded, it is compatible with OS X 10.11 up. 

EDIT: Looks like the XCode 7 link now just redirects to the AppStore. Perhaps the stuck on app install issue has been fixed? Anyone still getting it. 

EDIT2: There's one more way to download xcode package direcly: in the bottom of /download page there's a link see more downloads which points to the /download/more page where you can download all necessary files.