Change UIButton tint color while scrolling

Question

I have a custom table view header that becomes blurred when the user scrolls down. Id like to change the tint color of one of the navigation bar items items (its not a nav bar button item, just a UIButton). I have been using the tableviews contentOffset.y property to animate buttons, and blur the background image view. I need to do this to the tint color as well but I can figure out how.

For example this is code to shrink the profile pic and the hide some views using the alpha property

func movingUp(offset: CGFloat) {
    if infoView.alpha >= 0 {
        let alphaOffset = (offset - 133)/105.0
        infoView.alpha = alphaOffset*1.2
        profilePic.alpha = alphaOffset
    }

    if profileWidth.constant >= 45 {
        profilePic.layer.cornerRadius = (((offset - 133)/105.0) * 90)/2
        profileHeight.constant = ((offset - 133)/105.0) * 90
        profileWidth.constant = ((offset - 133)/105.0) * 90
    }
}

Answer 1

I have an answer that will help you here... http://www.oliverfoggin.com/controlling-animations-with-a-uiscrollview/

The idea is that you can move between two extreme values by using the current content offset and using it as a percentage based on the maximum offset.

In your case, it's easy as the colour is a simple inverse function of the percentage.

ie

let color = UIColor(white: 1.0 - percentage, alpha: 1.0)

When the percentage is 0.0 (ie top of the table) then the white value is 1.0 = white.

When the percentage is 1.0 (ie bottom of the table) then the white value is 0.0 = black.

I just realised that my post is in Objective-C. It should be very easy to convert to Swift as it just uses simple math functions. If you'd like me to convert it let me know and I'll put it here.