Add & Stop while running the project in XCode4

When we hit run but开发者_运维技巧ton in XCode4 & if project is already running,

it prompts as follows.

My question is

what does it will do if I tap on Add button ? Does it means, add local changes quickly to build/running application ?

It means it will run the program without stopping the old one

It will start the new compiled app without stopping the old build so your app runs two times now. This is useful if you have a workspace with two different apps that should both run simultaneously but more or less useless if you work on a single app.