UIButton and UIScrollView - iphone

Question

I have a UIScrollView that contains a long image, whose height is way more than a screen could hold at the current time. Now I want to place buttons all over the image. However, some of the buttons are below the view that you see when you haven't scrolled yet and after scrolling to the bottom of the image, the button I currently press is the one at the top that occupies the position of the screen itself when one hasn't scrolled yet. In short, not the button at the bottom is clicked when I scroll down and click on it, but the one at the top. How do I solve this? Note: my code is in Swift, so please write down code snippets in Swift and not Objective-C.
func makeImage(){
//might change the following to make it more dynamic later on
imageView = UIImageView(image: UIImage(named:brand.name + "-" + genderChoice.name + "-"+generalOverviewChoice.name+"-Detail.png"))
scrollView = UIScrollView(frame: view.bounds)
scrollView.autoresizingMask = UIViewAutoresizing.FlexibleWidth | UIViewAutoresizing.FlexibleHeight
imageView.frame = CGRectMake(0, 0, 375, imageView.frame.size.height/2)
scrollView.contentSize = CGSizeMake(375,imageView.frame.size.height)
scrollView.addSubview(imageView)
view.addSubview(scrollView)
}
func createButton(button: UIButton,x: CGFloat, y: CGFloat, width: CGFloat, height: CGFloat){
button.frame = CGRectMake(x, y, width, height)
button.addTarget(self, action: "btnTouched:", forControlEvents:.TouchUpInside)
self.view.addSubview(button)
}