Question

I met the exception called ‘Collection was mutated while being enumerated’ yesterday and saw some solutions.I’ve got another idea.If I set an argument called ‘lock’ and each time I enumerate I lock it then unlock it after enumeration.Every time I’ll operate it,like enumerating or add object, I lock it first then unlock it after the operation.
Could someone tell me if it will work?

Answer 1

I solved it.One of the problem is about thread safety.Use

    @synchronized (yourobject)
    {
    //do something with your object
    }

that will work.It means that it’ll lock ‘yourobject’ so that other thread can’t modify it.Then unlock it after the ‘}’

The other is some code about deleting objects in array.If you delete instantly,you’ll meet the exception called ‘Collection was mutated while being enumerated’.Create a temp array to contain objects you want to delete,then delete them all after the for loop.

 NSMutableArray *toDestroy = [NSMutableArray arrayWithCapacity:_contactor.count];
    for(Man *sprite in self.contactor)
    {
        if (sprite.hp<=0 && sprite.stat == stat_attack)
        {
            [sprite stopAllActions];
            [sprite animDead];
            [toDestroy addObject:sprite];
        }
    }
    [self.contactor removeObjectsInArray:toDestroy];

instead of

for(Man *sprite in self.contactor)
{
    if (sprite.hp<=0 && sprite.stat == stat_attack)
    {
        [sprite stopAllActions];
        [sprite animDead];
        [self.contactor removeObject:sprite];
    }
}