How to Build an iOS App
Building an iOS app in Xcode means compiling all the source code files in the project. It’s really exciting to see what you get when you build and run a project that you created from a template. Building and running an app is relatively simple; just follow these steps:
In the toolbar, choose a scheme from the Scheme pop-up menu located to the right of the Run and Stop buttons.
A scheme tells Xcode the purpose of the built product. The schemes in the Scheme pop-up menu specify which targets (actual products) to build, what build configuration to use when building them, which debugger to use when testing them, and which executable to launch when running them on the device or Simulator.
From the selected scheme, hold down the mouse button and slide to the right to choose your device or the simulator.
Choose one of the installed simulators. Do not choose iOS Device because that will run on a connected iPhone or iPad, and you need further preparation to do that.
Choose Product→Run from the main menu to build and run the application.
You can also click the Run button in the top-left corner of the Workspace window. The Activity viewer tells you all about the build progress, flags any build errors (such as compiler errors) or warnings, and (oh, yeah) tells you whether the build was successful.
This is what you’ll see in the Simulator (in the Portrait mode) when you tap the Master button. (The Master button is located in the view that's underneath the master view controller. Its purpose is to show the master view controller.) It’s not much to look at, but it's a start — and it is a functioning iPad app.
If you rotate the Simulator by choosing Hardware→Rotate Left, in the Simulator menu, you see a nice Split view.