How to use extensions to simplify Swift code?

Question

Say I have many functions that return more than one UIColor. Let's take a look at one of them:

func deepSkyBlue() -> UIColor {
    return UIColor(red: 0, green: 0.69, blue: 0.98, alpha: 1)
}

All my functions have alpha equal to 1.0, so it'd make sense to use an extension and omit one argument entirely. How can I do this?

Missing argument for parameter 'alpha' in call. In fact, I still have to find a way to implement the neverAlpha code into my UIColor functions. Thanks! — Cesare
– Cesare, Commented May 10, 2015 at 12:52
So the compiler error is not for neverAlpha, but is for deepSkyBlue? — Peter M
– Peter M, Commented May 10, 2015 at 12:54
I've posted an answer for you, so perhaps stop editing your question for a second and see if that works for you? — nhgrif
– nhgrif, Commented May 10, 2015 at 13:00

Cesare · Accepted Answer · 2015-10-29 15:41:18Z

4

If we want our alpha to be assumed as 1.0 when we don't pass it to the UIColor constructor, all we need to do is add a new constructor in an extension.

extension UIColor {
    convenience init(red: CGFloat, green: CGFloat, blue: CGFloat) {
        self.init(red: red, green: green, blue: blue, alpha: 1.0)
    }
}

And now we can use the three argument constructor you tried using:

static func deepSkyBlue() -> UIColor {
    return UIColor(red: 0, green: 0.69, blue: 0.98)
}

edited Oct 29, 2015 at 15:41

Cesare

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answered May 10, 2015 at 12:55

nhgrif

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