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 show me a decent tutorial or example to explain NSConditionLock, or possibly suggest a better method.

Answer 1

EDIT: as @Bonshington commented, this answer refers to NSCondition (as opposed to NSConditionLock):

- (void) method1 {

    [myCondition lock];
    while (!someCheckIsTrue)
        [myCondition wait];


    // Do something.


    [myCondition unlock];
}

- (void) method2 {

    [myCondition lock];


    // Do something.


    someCheckIsTrue = YES;
    [myCondition signal];
    [myCondition unlock];
}

The someCheckIsTrue can be anything, it could be a simple BOOL variable or even something like [myArray count] == 0 && color == kColorRed, it doesn’t matter. It only matters that in one method you check for a condition while you have the lock and in another method you make changes that can make the condition become true also while having the lock. The magic is the wait and signal part: the wait actually unlocks the lock and reacquires it after some other thread called signal.