Retrieve random object from NSSet

gistfile1.m

//Implemented based on the pseudo-code in http://stackoverflow.com/a/9981965/350761
int randomIndex = arc4random() % [set count];
__block int currentIndex = 0;
__block id selectedObj = nil;
[set enumerateObjectsUsingBlock:^(id obj, BOOL *stop) {
    if (randomIndex == currentIndex) { selectedObj = obj; *stop = YES; }
    else currentIndex++;
}];
return selectedObj;