Runar Ovesen Hjerpbakk

Science-based software development

Xcode - symbol(s) not found for architecture x86_64

So, I dabbled in Objective-C the other day, trying to use JSONModel to parse the following JSON to an Objective-C object named AppConfig:

{
    "SpotifyClientId": "[SpotifyClientId]",
    "SpotifyClientSecret": "[SpotifyClientSecret]",
    "YouTubeServiceId": "[YouTubeServiceId]"
}

Sounds straightforward.

The JSONModel documentation says:

declare properties in your header file with the name of the JSON keys
There’s no need to do anything in the implementation (.m) file.

Easy.

// AppConfig.h
#import <JSONModel/JSONModel.h>

@interface AppConfig : JSONModel
@property (nonatomic) NSString *SpotifyClientId;
@property (nonatomic) NSString *SpotifyClientSecret;
@property (nonatomic) NSString *YouTubeServiceId;
@end
// AppConfig.m
#import "AppConfig.h"

Some of you will already see the error of my ways.

Building the target gave this informative error message:

Error message during build

Undefined symbols for architecture x8664:
   “_OBJC_CLASS
$_AppConfig”, referenced from:
      objc-class-ref in AppDelegate.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

After Googling and finding this comment on Stack Overflow, I realized the AppConfig class was missing its implementation:

// AppConfig.m
#import "AppConfig.h"

@implementation AppConfig
@end

Finally, it builds!

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