What is causing this secondary damage?

Question

In my app delegate header, I have:

#import <UIKit/UIKit.h>

@interface CJSHAppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;

@end

When I try to run it, the @interface line gets the error, "Expected identifier or '('", and the @end line gets, "'@end' must appear in an Objective-C context", and after this, main.m gets "Use of undeclared identifier 'CJSHAppDelegate". None of these have happened before.

What is causing this, and what can be addressed? I would expect it to be secondary damage, but don't know where to look.

An English translation of the error message would be helpful; I believe the error is reported for Xcode-generated boilerplate code.

--EDIT--

The main.m, requested in a response, is:

//
//  Created by jonathan on 9/27/13.
//  Copyright (c) 2013 Jonathan Hayward. All rights reserved.
//

#import <UIKit/UIKit.h>

#import "CJSHAppDelegate.h"

int main(int argc, char * argv[])
{
    @autoreleasepool {
        return UIApplicationMain(argc, argv, nil, NSStringFromClass([CJSHAppDelegate class]));
    }
}