NSArray map reduce

gistfile1.m

typedef id(^mapFunction)(id obj);

typedef id(^reduceFunction)(id obj1, id obj2);

@implementation NSArray (NSArray_MapReduce)

- (id)map:(mapFunction)mapFunction reduce:(reduceFunction)reduceFunction;
{
    dispatch_queue_t reduceQueue = dispatch_queue_create(0, 0);
    dispatch_group_t group = dispatch_group_create();
    
    __block id result = nil;
    
    dispatch_apply([self count], dispatch_get_current_queue(), ^(size_t i){
    
        id obj = [self objectAtIndex:i];
        
        id newObj = mapFunction(obj);
        
        dispatch_group_async(group, reduceQueue, ^(){
            result = reduceFunction(result, newObj);
        });
    });
    
    dispatch_group_wait(group, DISPATCH_TIME_FOREVER);
    
    return result;
}

@end