I would like to make a menu which will have horizontal scrolling.
The menu contains total 16 categories. So I am planning to take 8 on first part and rest 8 on another p
You can accomplish you're goal using a UIScrollView and your UIButton objects, it would involve setting each button's frame / layout properties depending on what iOS version you're targeting. (As in Eric's answer).
However, if you're targeting iOS 6 and above, using a UICollectionView where your items/cells are the buttons, then you can get the horizontal scrolling "menu bar" for free. There are plenty of SO posts on this, but the main idea is to use a flow layout where the item size has a height such that there will only be one row of items (just make the item height the same as the collection view's height).
EDIT:
I should say, this might seem like overkill (and maybe it is), but you will end up with a much more flexible component in case requirements change in the future. It also doesn't result in much extra code and abstracts away tedious layout details.
If all you're doing is adding buttons to a horizontal scroll view you would do something like follows...
- (void)createScrollMenu
{
UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, 100)];
int x = 0;
for (int i = 0; i < 8; i++) {
UIButton *button = [[UIButton alloc] initWithFrame:CGRectMake(x, 0, 100, 100)];
[button setTitle:[NSString stringWithFormat:@"Button %d", i] forState:UIControlStateNormal];
[scrollView addSubview:button];
x += button.frame.size.width;
}
scrollView.contentSize = CGSizeMake(x, scrollView.frame.size.height);
scrollView.backgroundColor = [UIColor redColor];
[self.view addSubview:scrollView];
}
This will create a scrollview with a height of 100, width as big as its parent, and add 8 buttons to it.