Objective-C Singleton

Singleton pattern implementation in Objective-C

MySingleton.h

#import <Foundation/Foundation.h>

@interface MySingleton : NSObject 

+ (MySingleton*) instance;

@end

MySingleton.m

#import "MySingleton.h"

@implementation MySingleton

static MySingleton *myInstance;
+ (MySingleton*) instance {
    if (myInstance == nill) {
        myInstance = [[super allocWithZone:NULL] init];
    }
    return myInstance;
}

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

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

- (id) retain {
    return self;
}

- (NSUInteger) retainCount {
    return NSUIntegerMax;
}

- (oneway void) release {
}

- (id) autorelease {
    return self;
}

@end

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