声明的extern的NSString导致链接错误 [英] Declaring extern NSString causes linker error

问题描述

这是荒谬的，即时通讯试图建立一个完善的布尔在app声音转的。我不断收到

This is ridiculous, im trying to create a sound bool to turn of in app sounds. I keep getting

Undefined symbols for architecture i386:
"_kPlaySoundPrefsKey", referenced from:
  -[AppDelegate application:didFinishLaunchingWithOptions:] 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)

我已经检查了我的所有文件都在构建阶段联系在一起，我删除了的appdelegate .M那里即时得到错误之前我甚至去调用我的任何视图控制器的布尔，并重新导入它在构建阶段。经过我已经制定相关framweworks。我甚至已经查了previous应用程序，我用同样的code和code这似乎是没有错误完全一样（以x $ C $的C previous版本内置）制成。服用右后卫基本原则我，只要我加入以下code到我的应用程序委托，

I have checked that all my files are linked in build phases, I have deleted the appdelegate .m where im getting the error before I even get to call the bool in any of my view controllers, and re imported it in build phases. Checked I have relevant framweworks in place. I have even checked a previous app I made with same code and the code it appears to be exactly the same with no error (built with previous version of xcode). Taking it right back to basics I get the error as soon as I add the following code to my App Delegate,

.H

#import <UIKit/UIKit.h>
extern NSString *kPlaySoundPrefsKey;

@interface AppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;

@end

.M

#import "AppDelegate.h"
#import <AudioToolbox/AudioToolbox.h> 

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:    (NSDictionary *)launchOptions
 {

NSDictionary *defaultDict = [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES]
 forKey:kPlaySoundPrefsKey];

return YES;
}

如果我更改的extern的NSString * kPlaySound prefsKey; 到的NSString * kPlaySound prefsKey; 然后它建立崩溃...林的想法，现在

If I change extern NSString *kPlaySoundPrefsKey; to NSString *kPlaySoundPrefsKey; it builds then crashes...Im out of ideas now

推荐答案

感谢您的帮助球员

我添加

的NSString * kPlaySound prefsKey = @playSoundKey;

[NSUserDefaults的standardUserDefaults] registerDefaults：defaultDict];

到应用程序委托。这固定它

to app delegate. That fixed it

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