#import "CPDConstants.h"
For me this error appears after cloning the project from a repository. Someone removed a white space from the projects name (renamed: "The Project" to "TheProject") which caused some Build Settings errors to unvalid paths.
Sometimes reading the whole error logs is not a bad idea....
Try this - click on the name of your project on the list of files/folders on the left in Xcode (at the very top of the list). Look at the "Targets" section on the left-hand side of the window to the right. Likely, there's two listed with the second being a "test" item. Right-click on that item and select "delete". Then try to run the project again.
This problem usually occurs when there are more than two versions of XCode are installed in which different Swift versions incorporated for Ex. XCode 6.4 and XCode 7.3 are installed which are running Swift 1.2 and Swift 2.0. By mistake you tries to compile code with icorrect version for Ex. your project in in Swift 1.2 and you tries to compile it with xcode 7.3. In this case drive data stores information for swift version but when you tries to compile code with correct XCode it gives error.
To resolve this
Delete drive Data
a. In Xcode select preferences
Had this happen in a team using git. One of the team members added a class from an external source but didn't copy it into the repo directory. The local version compiled fine but the continuous integration failed with this error.
Reimporting the files and adding them to the directory under version control fixed it.
I too had this error. But in my case, and I'm sure I'll be a one off here, I had accidentally deleted main.m when I hit the delete key after the app had crashed on the iPhone simulator.
After a crash, Xcode shows the main.m file and when I had hit delete, I had accidentally deleted the main.m file from my project, as it is easy to do when a file name is highlighted, not the code in the detail view.
Main.m normally resides in a group or folder named supporting files in the project file manager. I had not noticed this happened until it failed to build and run next time around and then I had to re-read the error message more closely and saw it said main.m is missing.
Thank you all for your input, but just in case there is someone in my position check for any file names in red showing missing files and restore them from a backup if you have it.
My problem was that under Build Phases -> Compile Sources, I added a compiler flag for a file, but I had misspelled it. It was supposed to be:
-fno-obj-arc
to show that this file does not use ARC.
@Spoek's answer is right,
But If you won't find file in red color, then find the one with low opacity,
see this image,
The first one is there but second one is note there, so delete it.
This happened to me and it took me an hour to find it. In my case I had typed too fast and did:
[seld method];
instead of:
[self method];
Seriously! I don't know why it didn't catch this in a more recognizable way. But it was of course looking for a class called "seld".
