UIScrollView: paging horizontally, scrolling vertically?

Question

How can I force a UIScrollView in which paging and scrolling are on to only move vertically or horizontally at a given moment?

My understanding is that

Answer 1

For future reference, I built upon Andrey Tanasov's answer and came up with the following solution that works fine.

First define a variable to store the contentOffset and set it to 0,0 coordinates

var positionScroll = CGPointMake(0, 0)

Now implement the following in the scrollView delegate:

override func scrollViewWillBeginDragging(scrollView: UIScrollView) {
    // Note that we are getting a reference to self.scrollView and not the scrollView referenced passed by the method
    // For some reason, not doing this fails to get the logic to work
    self.positionScroll = (self.scrollView?.contentOffset)!
}

override func scrollViewDidScroll(scrollView: UIScrollView) {

    // Check that contentOffset is not nil
    // We do this because the scrollViewDidScroll method is called on viewDidLoad
    if self.scrollView?.contentOffset != nil {

        // The user wants to scroll on the X axis
        if self.scrollView?.contentOffset.x > self.positionScroll.x || self.scrollView?.contentOffset.x < self.positionScroll.x {

            // Reset the Y position of the scrollView to what it was BEFORE scrolling started
            self.scrollView?.contentOffset = CGPointMake((self.scrollView?.contentOffset.x)!, self.positionScroll.y);
            self.scrollView?.pagingEnabled = true
        }

        // The user wants to scroll on the Y axis
        else {
            // Reset the X position of the scrollView to what it was BEFORE scrolling started
            self.scrollView?.contentOffset = CGPointMake(self.positionScroll.x, (self.scrollView?.contentOffset.y)!);
            self.collectionView?.pagingEnabled = false
        }

    }

}

Hope this helps.