Where do I put common utility functions in iOS 8 + Swift

Question

I have the following method (for instance) that I'd like to be able to use from any ViewController in an iOS + Swift project:

func initializeBlurEffectOnGivenUIView(UIViewToBeBlurred: UIView) {

    let UIViewToBeBlurredHeight = UIViewToBeBlurred.frame.size.height
    let UIViewToBeBlurredWidth = UIViewToBeBlurred.frame.size.width
    let UIViewToBeBlurredX = UIViewToBeBlurred.frame.origin.x
    let UIViewToBeBlurredY = UIViewToBeBlurred.frame.origin.y

    let blurEffect:UIBlurEffect = UIBlurEffect(style: UIBlurEffectStyle.Light)
    let vibrancyEffect = UIVibrancyEffect(forBlurEffect: blurEffect)

    let vibrancyEffectView = UIVisualEffectView(effect: vibrancyEffect)
    let blurEffectView:UIVisualEffectView = UIVisualEffectView(effect: blurEffect)
    blurEffectView.frame = CGRectMake(UIViewToBeBlurredX, UIViewToBeBlurredY, UIViewToBeBlurredWidth, UIViewToBeBlurredHeight)
    blurEffectView.contentView.addSubview(vibrancyEffectView)

    UIViewToBeBlurred.addSubview(blurEffectView)
}

I have more common helpers such as there that I'd like to make available as well. How do I structure the application to achieve this?

Answer 1

If the function is to be a free global, put the function at the top level of any file. (Just don't accidentally repeat yourself and put the same function at the top level of all files.) That, for example, is what I do with the delay utility function I describe here: dispatch_after - GCD in swift?

In the particular case of the example you gave, however, I'd probably put it in an extension on UIView. I'd rewrite it as an instance method, so that instead of blurring another view, we'd start with an existing view and blur self.

Answer 2

Use an extension, like this:

extension UIView {
    func initializeBlurEffect() {

        let height = self.frame.size.height
        let width = self.frame.size.width
        let x = self.frame.origin.x
        let y = self.frame.origin.y

        let blurEffect:UIBlurEffect = UIBlurEffect(style: UIBlurEffectStyle.Light)
        let vibrancyEffect = UIVibrancyEffect(forBlurEffect: blurEffect)

        let vibrancyEffectView = UIVisualEffectView(effect: vibrancyEffect)
        let blurEffectView:UIVisualEffectView = UIVisualEffectView(effect: blurEffect)
        blurEffectView.frame = CGRectMake(x, y, width, height)
        blurEffectView.contentView.addSubview(vibrancyEffectView)

        self.addSubview(blurEffectView)
    }
}

Then call it like this:

myview.initializeBlurEffect()