Whats the equivalent of synchronized in Objective-C?

Question

What is the equivalent of java synchronized in objective c? I want to be able to make my singleton method safe, so when it's bein called from 2 different threads, they try to use it 1 by 1.

+(MyObject*) getSharedObject
{
     if(!singleton)
     {
          singleton = [[MyObject alloc] init];
     }
     return singleton;
}

Answer 1

Obj-C has a synchronized construct

-(MyObject*) getSharedObject
{
@synchronized(something)
{
     if(!singleton)
     {
          singleton = [[MyObject alloc] init];
     }
     return singleton;
}
}

returning from within a synchronized block does the 'right' thing