duplicate interface declaration for class 'test_coredataAppDelegate'
Solution 1
There are two possibilities:
- you have two interfaces with the same name. Use Xcode's find in project menu option to find instances of
test_coredataAppDelegate
. Then rename one of the interfaces - somehow you have managed to import the .h file twice. Check to make sure you always use
#import
and not#include
.
Edit:
A bit more info on #import
/#include
:
#include
blindly includes the file at the location of the #include
statement. This means that if you #include
a file twice in your .m
you will get two copies of the file. Almost all traditional C #include
files have something like the following bracketing all the content:
// some_file.h
#if !defined SOME_FILE_H
#define SOME_FILE_H
// entire content of #include file
#endif
The above is sometimes referred to as an include guard macro.
In Objective-C, if you #import
a file, a check is performed by the compiler to make sure it has not already been imported. Consequently the guards are usually omitted. So if you #include
a file that was supposed to be #import
ed, neither check will be done and you will sometimes get duplicate definitions.
Solution 2
This happen because you have a copy of that resource in your finder. It is not necessary had added it in your project. You should find in your finder the files with the same name and delete the files duplicated.
Solution 3
In my case replacing
#import "Mixpanel.h"
to
#import <Mixpanel/Mixpanel.h>
Resolved the error
Solution 4
I deleted date model class and create new one and issue fixed. also delete from project directory.
Solution 5
I have got the solution for this first copy that file for example video.m is giving this error so copy this file and delete that file and just paste it again and add that file to project again :)
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Ali
Updated on December 21, 2020Comments
-
Ali over 3 years
two errors suddenly fired in this piece of code - duplicate interface declaration for class 'test_coredataAppDelegate' - redefinition of 'struct test_coredataAppDelegate'
#import <UIKit/UIKit.h> #import <CoreData/CoreData.h> @interface test_coredataAppDelegate : NSObject <UIApplicationDelegate, UITabBarControllerDelegate> { ///////////////////New parts ///////////////////////// NSManagedObjectModel *managedObjectModel; NSManagedObjectContext *managedObjectContext; NSPersistentStoreCoordinator *persistentStoreCoordinator; ////////////////////////////////////////////// UIWindow *window; UITabBarController *tabBarController; } @property (nonatomic, retain, readonly) NSManagedObjectModel *managedObjectModel; @property (nonatomic, retain, readonly) NSManagedObjectContext *managedObjectContext; @property (nonatomic, retain, readonly) NSPersistentStoreCoordinator *persistentStoreCoordinator; @property (nonatomic, retain) IBOutlet UIWindow *window; @property (nonatomic, retain) IBOutlet UITabBarController *tabBarController; @end
how to fix that please
Best regards
-
Alyoshak over 10 yearsHad somehow copied an extra version of file. Thanks.
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Robert J. Clegg over 9 yearsDid the same mistake had the same file in the project directory twice. Thanks!
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bcattle over 8 yearsThis happened to me. Why in the world would XCode vacuum in files that aren't in the project?
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Yossi almost 4 yearsI don't see how to "Use Xcode's find in project menu option to find instances of xxx". I am using Xcoder 11.3. No Project menu option...
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JeremyP almost 4 years@Yossi it's moved since 2011. The "find in project" functionality is now part of the search table in the navigation bar.
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Yossi almost 4 yearsHmmm... Didn't notice the messages are from 2011... But we are still here :) "Navigation bar' = the Xcode/File/Edit/... menu?
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JeremyP almost 4 years@Yossi No, the pane to the left of the main editor window.