Editing Build Settings in xcode 4

问题:

I have been unable to work out how to edit build settings using the pop-up shown below.

I can enter multiple lines in the pop-up by clicking the '+'. My questions are :-

1. What is the checkbox next to the setting used for?
2. Once I have entered one or more settings in the pop-up, how do I make them transfer to the setting I am editing. There isn't a 'Save' button, and clicking off the pop-up closes it but doesn't seem to save the entered data.

Thanks

回答1:

To delete, check the checkbox and click "-". To make a new one, click "+". To save, click "Done".

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