move xcode project causes red text (missing files from project)

Here is how to locate the missing (red) files using the Xcode 4 interface:

1. Select the file or files in the left hand Project Navigator (the folder icon)
2. In the right sidebar click on "File Inspector" which is the leftmost icon resembling a page
3. In the "Identity and Type" section, there is a grey box labeled "Location".
4. Click on the small icon to the lower left that resembles a file browser - this will come up with a file browser to locate the file.

Voila, you are done.

Xcode 7

1.) Right click on the red (missing) file.

2.) Select "Show File Inspector"

3.) Look at the right hand side of the screen under "Identity and Type" between "Location" and "Full Path"

4.) Click on the folder icon to the right of the file name.

5.) Navigate to the file's new location in the pop-up window and select the file.

I encountered this issue when copying my project from one mac to another.The solution for me:

assuming your files are grouped (in folder)

1. from xcode open the group in file inspector

2. The group will probably be missing the absolute path.

3. press the little icon nearby to pick the folder to associate the group with.

4. restart xcode to see the changes.