Objective C - Singleton class instane not initialising

I have declared a class called 'SharedTranslationsArray' that I want to use in multiple view controllers.

I then in the view controller MainViewController.m I declare an instance of the variable in the "ViewDidLoadMethod" and try to add an object to the array in the singleton instance. There are no compilation errors / warning but the items are not added to the array.

Any advice would be appreciated. The relevant code samples are below Thanks

**SharedTranslations.h**
#import "Foundation/Foundation.h"

@interface SharedTranslationsArray : NSObject {
NSMutableArray *translation_set;
}

static SharedTranslationsArray *sharedInstance;
@property (nonatomic, retain) NSMutableArray *translation_set;
+ (SharedTranslationsArray*) sharedInstance;

@end

**SharedTranslations.m** 

#import "SharedTranslationsArray.h"

static SharedTranslationsArray *sharedInstance;
@implementation SharedTranslationsArray
@synthesize translation_set;

\+ (SharedTranslationsArray*)sharedInstance
{   
        if (sharedInstance == nil) {            
            sharedInstance = [[super allocWithZone:NULL] init];


        }
    return sharedInstance;
}

\ + (id)allocWithZone:(NSZone *)zone 
{   
    return [[self sharedInstance]retain];   
}

\ - (id)copyWithZone:(NSZone *)zone
{
    return self;    
}

\ - (id)retain
{   
    return self;    
}

\ - (unsigned)retainCount
{
    return NSUIntegerMax;  //denotes an object that cannot 开发者_运维问答be released
}

\ - (void)release
{
    //do nothing
}

\ - (id)autorelease
{
    return self;    
}

@end

**MainViewController.m**
#import "MainViewController.h"
#import "Translations.h"
#import "SharedTranslationsArray.h"

@implementation MainViewController
\- (void)viewDidLoad {
    NSMutableString *temp = [[NSMutableString alloc] init];

    SharedTranslationsArray *ts = [SharedTranslationsArray sharedInstance];

    Translations *translation = [Translations new];
    translation.shortText = @"short";
    translation.fullText = @"long";
    translation.canDeleted = FALSE;
    translation.active = TRUE;
    [ts.translation_set addObject:translation];
}
@end

Make sure you actually initialize translation_set!

+ (SharedTranslationsArray*)sharedInstance
{   
        if (sharedInstance == nil) {            
            sharedInstance = [[super allocWithZone:NULL] init];

            sharedInstance.translation_set = [NSMutableArray array];
        }
    return sharedInstance;
}

Also why are you calling it a set but declaring it as an array? If the order of the objects is not important you could make it an NSMutableSet