KVO granular notifications on NSMutableArray

gistfile1.m

/*
Thanks to @_bejo
*/

- (void)_insertGlobalRoomMessage:(id)msg atIndex:(NSUInteger)index
{
    NSIndexSet *changeSet = [NSIndexSet indexSetWithIndex:index];
    [self willChange:NSKeyValueChangeInsertion valuesAtIndexes:changeSet forKey:@"globalRoomMessages"];
    [(NSMutableArray *)self.globalRoomMessages insertObject:msg atIndex:index];
    [self didChange:NSKeyValueChangeInsertion valuesAtIndexes:changeSet forKey:@"globalRoomMessages"];
}


- (void)_removeGlobalRoomMessageAtIndex:(NSUInteger)index
{
    NSIndexSet *changeSet = [NSIndexSet indexSetWithIndex:index];
    [self willChange:NSKeyValueChangeRemoval valuesAtIndexes:changeSet forKey:@"globalRoomMessages"];
    [(NSMutableArray *)self.globalRoomMessages removeObjectAtIndex:index];
    [self didChange:NSKeyValueChangeRemoval valuesAtIndexes:changeSet forKey:@"globalRoomMessages"];
}


- (void)_removeGlobalRoomMessagesInRange:(NSRange)range
{
    NSIndexSet *changeSet = [NSIndexSet indexSetWithIndexesInRange:range];
    [self willChange:NSKeyValueChangeRemoval valuesAtIndexes:changeSet forKey:@"globalRoomMessages"];
    [(NSMutableArray *)self.globalRoomMessages removeObjectsInRange:range];
    [self didChange:NSKeyValueChangeRemoval valuesAtIndexes:changeSet forKey:@"globalRoomMessages"];
}