how can I expand the hit area of a specific UIButton in Swift?

Question

In my application I have a UIButton that is quite small, so I thought about increasing the hit area of it.

I found an extension for that:

fileprivate let minimumHitArea = CGSize(width: 100, height: 100)

extension UIButton {
    open override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
        // if the button is hidden/disabled/transparent it can't be hit
        if self.isHidden || !self.isUserInteractionEnabled || self.alpha < 0.01 { return nil }

        // increase the hit frame to be at least as big as `minimumHitArea`
        let buttonSize = self.bounds.size
        let widthToAdd = max(minimumHitArea.width - buttonSize.width, 0)
        let heightToAdd = max(minimumHitArea.height - buttonSize.height, 0)
        let largerFrame = self.bounds.insetBy(dx: -widthToAdd / 2, dy: -heightToAdd / 2)

        // perform hit test on larger frame
        return (largerFrame.contains(point)) ? self : nil
    }
}

but when I use it, every button in my app has a bigger hit area. I want to increase it to only one specialButton - how can I do it?

Answer 1

Don't expand the hit area; shrink the drawing area. Make the button a subclass of UIButton, and in that subclass, implement rect methods, along these lines:

class MyButton : UIButton {
    override func contentRect(forBounds bounds: CGRect) -> CGRect {
        return bounds.insetBy(dx: 30, dy: 30)
    }
    override func backgroundRect(forBounds bounds: CGRect) -> CGRect {
        return bounds.insetBy(dx: 30, dy: 30)
    }
}

Now the button is tappable 30 points outside its visible background.