Using dispatch queues instead of locks and synchronization blocks

dispatch_async_blocks.m

// feeder methods to test
        self.counter = 10;
        [self testThreads];
        [self serialQs];
 
-(void) serialQs {
    
    dispatch_queue_t dispatchQueue = dispatch_queue_create("com.darshan.learn.dispatch", DISPATCH_QUEUE_SERIAL);
    
    __weak typeof (self) weakSelf = self;
    dispatch_async(dispatchQueue, ^{
        for (int i=0; i<5; i++) {
            [weakSelf normalCounter];
        }
    });
    
    dispatch_async(dispatchQueue, ^{
        for (int i=0; i<5; i++) {
            [weakSelf normalCounter];
        }
    });
 
}
 
-(void) testThreads {
    for (int i=0; i<10; i++) {
        NSThread *thread = [[NSThread alloc] initWithTarget:self selector:@selector(decrementCounterWithLocks) object:nil];
        [thread start];
    }
}
 
-(void) normalCounter {
    NSLog(@"decrement counter %d", --self.counter);
}
 
-(void) decrementCounter {
    @synchronized(self) {
        NSLog(@"decrement counter %d", --self.counter);
    }
}
 
-(void) decrementCounterWithLocks {
    NSLock *lock = [[NSLock alloc] init];
    [lock tryLock];
    NSLog(@"decrement counter %d", --self.counter);
    [lock unlock];
}