Singleton in iOS 5?

Question

Hi I had an implementation previous versions of iOS for a singleton as follows:

.h file

@interface CartSingleton : NSObject 
{

}
+(CartSingleton *)          


        

Answer 1

The dispatch_once snippet is functionally identical to other one. You can read about it at http://developer.apple.com/library/mac/#documentation/Darwin/Reference/Manpages/man3/dispatch_once.3.html.

This is what I use for singletons:

+ (MySingleton*) getOne {
    static MySingleton* _one = nil;

    @synchronized( self ) {
        if( _one == nil ) {
            _one = [[ MySingleton alloc ] init ];
        }
    }

    return _one;
}

NOTE: In most cases, you do not even need to use @synchronized (but it is safe this way).