I started a new iOS project in Xcode. Added two files: "constants.h" and "constants.m" with this content I saw here in other articles:
Constants.h
#import <Foundation/Foundation.h>
/// Holds the username for connection to the API
extern NSString * const PSUsername_preferences;
/// Holds the password for connection to the API
extern NSString *const PSPassword_preferences;
///Holds the (hopefully) secure server URL. (Defaults to https://API.SomewhatURL.de)
extern NSString *const PSServername_preferences;
And the constants.m:
#import "Constants.h"
NSString *const PSUsername_preference = @"username_preferences";
NSString *const PSPassword_preference = @"password_preferences";
NSString *const PSServer_preference = @"servername_preferences";
I am sure, the .m file is assigned to build for my ios-target. I am also sure, the file is added under Build Configurations- Compile Sources.
Next I added the "Constats.h" to my pch - file:
#ifdef __OBJC__
#import <UIKit/UIKit.h>
#import <Foundation/Foundation.h>
#import "Constants.h"
#endif
and I can assign one of these in let say AddDelegate
:
NSString * value = PSUsername_preferences;
Nice. But: If I try to build this, I get a strange linker error:
Undefined symbols for architecture i386: "_PSUsername_preferences", referenced from: -[AppDelegate applicationWillResignActive:] in AppDelegate.o ld: symbol(s) not found for architecture i386 clang: error: linker command failed with exit code 1 (use -v to see invocation)
This happens with a new created project just for this case. My build settings seem OK and I already checked 'Architectures' path under Build-Settings. All of they show 'ArmV7' but not i386, so whats going on?
I tested it on Xcode 4.6.3
as well as under Xcode 5
.
Read your constant names letter by letter. Or add some whitespace for easier readability.
extern NSString * const PSUsername_preferences;
NSString * const PSUsername_preference
You see the difference? Add the letter s
at the end of your definitions.
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