How do I use NSConditionLock? Or NSCondition

Question

I am try to make one function wait for another, and I would like to use NSCondionLock in order to accomplish this. I am not asking for help, but really hoping someone could

Answer 1

NSConditionLock example program.

#import 

#define IDLE 0
#define START 1
#define TASK_1_FINISHED 2
#define TASK_2_FINISHED 3
#define CLEANUP_FINISHED 4

#define SHARED_DATA_LENGTH 1024 * 1024 * 1024

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        NSConditionLock *lock = [[NSConditionLock alloc] initWithCondition:IDLE];
        char *shared_data = calloc(SHARED_DATA_LENGTH, sizeof(char));

        [NSThread detachNewThreadWithBlock:^{
            [lock lockWhenCondition:START];

            NSLog(@"[Thread-1]: Task 1 started...");
            for (size_t i = 0; i < SHARED_DATA_LENGTH; i++) {
                shared_data[i] = 0x00;
            }
            [lock unlockWithCondition:TASK_1_FINISHED];
        }];

        [NSThread detachNewThreadWithBlock:^{
            [lock lockWhenCondition:TASK_1_FINISHED];
            NSLog(@"[Thread-2]: Task 2 started...");
            for (size_t i = 0; i < SHARED_DATA_LENGTH; i++) {
                char c = shared_data[i];
                shared_data[i] = ~c;
            }
            [lock unlockWithCondition:TASK_2_FINISHED];
        }];

        [NSThread detachNewThreadWithBlock:^{
            [lock lockWhenCondition:TASK_2_FINISHED];

            NSLog(@"[Thread-3]: Cleaning up...");
            free(shared_data);
            [lock unlockWithCondition:CLEANUP_FINISHED];
        }];

        NSLog(@"[Thread-main]: Threads set up. Waiting for 2 task to finish");
        [lock unlockWithCondition:START];
        [lock lockWhenCondition:CLEANUP_FINISHED];
        NSLog(@"[Thread-main]: Completed");
    }
    return 0;
}