About the Scheme Editing Dialog
Edit Xcode schemes using the Scheme editing dialog. To edit a scheme, choose Edit Scheme from the Scheme toolbar menu or choose Product > Scheme > Edit Scheme.
A scheme is a collection of settings that specify which targets to build, what build configuration to use, and the executable environment to use when the product specified by the target is launched. When you open an existing project (or create a new one), Xcode automatically creates a scheme for each target.
To choose the active scheme and the run destination, you use the Scheme toolbar menu in the Xcode workspace window. The Scheme toolbar menu lets you select a combination of scheme and destination, but the two are distinct. A scheme does not include the destination.
You can use the pop-up menus at the top of the scheme editing dialog to choose a different active scheme or destination. When you change to a different scheme, all the settings change to whatever's set for that scheme. When you change the destination, nothing else changes.
The Breakpoints button toggles all breakpoints off and on.
The dialog allows you to specify many settings that affect your workflow. The left column lists actions that correspond to commands in the Product menu: Run, Test, Profile, Analyze, and Archive. Build is a special item that allows you to select the targets to build for each of these actions.
When you select an action in the list, Xcode displays a pane with settings that affect what happens when you choose the corresponding command. For example, the settings in the Run pane configure the Run command.
You can customize each action in a scheme. There are phases before and after each action to run shell scripts and send email. To edit the pre-action and post-action phases for a particular action, click the action’s disclosure triangle.
When you change a setting in a scheme, the change takes effect immediately.
One way to create a new scheme is to click the Duplicate Scheme button, which uses the active scheme as a template. To display and manage a list of existing schemes, click the Manage Schemes button.
If your workspace contains projects and targets that build more than one product, you can create separate schemes for the different products. For projects with large codebases and multiple developers, you can create multiple schemes to represent distinct subsystems.