UIColor greatest practices in Swift

What are shade fashions and shade areas?

A shade mannequin is a technique of describing a shade.

• RGB – Pink+Inexperienced+Blue
• HSB – Hue+Saturation+Brightness

There are a number of different shade fashions, however in case you are coping with iOS colours you have to be aware of these two above. Often you will work with the RGBA & HSBA shade fashions that are mainly the identical as above prolonged with the alpha channel the place the letter A stands for that. 😉

A shade house is the set of colours which may be displayed or reproduced in a medium (whether or not saved, printed or displayed). For instance, sRGB is a selected set of intensities for crimson, inexperienced and blue and defines the colours that may be reproduced by mixing these ranges of crimson, inexperienced and blue.

Sufficient from the speculation, let’s do some shade magic! 💫💫💫

Tips on how to work with UIColor objects utilizing RGBA and HSBA values in Swift?

Do you bear in mind the outdated Paint program from old-school Home windows instances?

I’ve used Microsoft Paint rather a lot, and I liked it. 😅

Again then with none CS information I used to be at all times questioning concerning the numbers between 0 and 255 that I needed to choose. In case you are working with RGB colours you normally outline your shade the identical manner, besides that in iOS the values are between 0 and 1, however that is only a completely different illustration of the fraction of 255.

So you may make a shade with RGB codes utilizing the identical logic.

UIColor(crimson: CGFloat(128)/CGFloat(255),
        inexperienced: CGFloat(128)/CGFloat(255),
        blue: CGFloat(128)/CGFloat(255),
        alpha: 1)

UIColor(crimson: 0.5, inexperienced: 0.5, blue: 0.5, alpha: 1)

See? Fairly simple, huh? 👍

Alternatively you should use HSB values, nearly the identical logic applies for these values, besides that hue goes from 0 ’til 360 (due to the precise shade wheel), nonetheless saturation and brightness are measured in a “% like” format 0-100, so it’s a must to take into consideration these numbers when you map them to floating level values.

UIColor(hue: CGFloat(120)/CGFloat(360), saturation: 0.5, brightness: 0.5, alpha: 1)
UIColor(hue: 0.3, saturation: 0.5, brightness: 0.5, alpha: 1)

Now let’s reverse the state of affairs and let me present you find out how to get again these parts from an precise UIColor occasion with the assistance of an extension.

public extension UIColor {
    public var rgba: (crimson: CGFloat, inexperienced: CGFloat, blue: CGFloat, alpha: CGFloat) {
        var r: CGFloat = 0
        var g: CGFloat = 0
        var b: CGFloat = 0
        var a: CGFloat = 0
        self.getRed(&r, inexperienced: &g, blue: &b, alpha: &a)
        return (r, g, b, a)
    }

    public var hsba: (hue: CGFloat, saturation: CGFloat, brightness: CGFloat, alpha: CGFloat) {
        var h: CGFloat = 0
        var s: CGFloat = 0
        var b: CGFloat = 0
        var a: CGFloat = 0
        self.getHue(&h, saturation: &s, brightness: &b, alpha: &a)
        return (h, s, b, a)
    }
}

So right here it’s find out how to learn the crimson, inexperienced blue slash hue saturation brightness and alpha parts from a UIColor. With this little neat extension you’ll be able to merely get the part values and use them via their correct names.

UIColor.yellow.rgba.crimson
UIColor.yellow.hsba.hue

Tips on how to convert HEX colours to RGB and vica versa for UIColor objects in Swift?

iOS developer 101 course, first questions:

• How the fuck can I create a UIColor from a hex string?
• Tips on how to convert a hex shade to a UIColor?
• Tips on how to use a hext string to make a UIColor?

Okay, possibly these aren’t the primary questions, however it’s positively inside widespread ones. The reply is fairly easy: via an extension. I’ve a very nice answer to your wants, which can deal with many of the instances like utilizing just one, 2, 3 or 6 hex values.

public extension UIColor {

    public comfort init(hex: Int, alpha: CGFloat = 1.0) {
        let crimson = CGFloat((hex & 0xFF0000) >> 16) / 255.0
        let inexperienced = CGFloat((hex & 0xFF00) >> 8) / 255.0
        let blue = CGFloat((hex & 0xFF)) / 255.0

        self.init(crimson: crimson, inexperienced: inexperienced, blue: blue, alpha: alpha)
    }

    public comfort init(hex string: String, alpha: CGFloat = 1.0) {
        var hex = string.trimmingCharacters(in: .whitespacesAndNewlines).uppercased()

        if hex.hasPrefix("#") {
            let index = hex.index(hex.startIndex, offsetBy: 1)
            hex = String(hex[index...])
        }

        if hex.rely < 3 {
            hex = "(hex)(hex)(hex)"
        }

        if hex.vary(of: "(^[0-9A-Fa-f]{6}$)|(^[0-9A-Fa-f]{3}$)", choices: .regularExpression) != nil {
            if hex.rely == 3 {

                let startIndex = hex.index(hex.startIndex, offsetBy: 1)
                let endIndex = hex.index(hex.startIndex, offsetBy: 2)

                let redHex = String(hex[..<startIndex])
                let greenHex = String(hex[startIndex..<endIndex])
                let blueHex = String(hex[endIndex...])

                hex = redHex + redHex + greenHex + greenHex + blueHex + blueHex
            }

            let startIndex = hex.index(hex.startIndex, offsetBy: 2)
            let endIndex = hex.index(hex.startIndex, offsetBy: 4)
            let redHex = String(hex[..<startIndex])
            let greenHex = String(hex[startIndex..<endIndex])
            let blueHex = String(hex[endIndex...])

            var redInt: CUnsignedInt = 0
            var greenInt: CUnsignedInt = 0
            var blueInt: CUnsignedInt = 0

            Scanner(string: redHex).scanHexInt32(&redInt)
            Scanner(string: greenHex).scanHexInt32(&greenInt)
            Scanner(string: blueHex).scanHexInt32(&blueInt)

            self.init(crimson: CGFloat(redInt) / 255.0,
                      inexperienced: CGFloat(greenInt) / 255.0,
                      blue: CGFloat(blueInt) / 255.0,
                      alpha: CGFloat(alpha))
        }
        else {
            self.init(crimson: 0.0, inexperienced: 0.0, blue: 0.0, alpha: 0.0)
        }
    }

    var hexValue: String {
        var shade = self

        if shade.cgColor.numberOfComponents < 4 {
            let c = shade.cgColor.parts!
            shade = UIColor(crimson: c[0], inexperienced: c[0], blue: c[0], alpha: c[1])
        }
        if shade.cgColor.colorSpace!.mannequin != .rgb {
            return "#FFFFFF"
        }
        let c = shade.cgColor.parts!
        return String(format: "#%02Xpercent02Xpercent02X", Int(c[0]*255.0), Int(c[1]*255.0), Int(c[2]*255.0))
    }
}

Right here is how you should use it with a number of enter variations:

let colours = [
    UIColor(hex: "#cafe00"),
    UIColor(hex: "cafe00"),
    UIColor(hex: "c"),
    UIColor(hex: "ca"),
    UIColor(hex: "caf"),
    UIColor(hex: 0xcafe00),
]
let values = colours.map { $0.hexValue }
print(values) 

As you’ll be able to see I’ve tried to duplicate the habits of the CSS guidelines, so you’ll have the liberty of much less characters if a hext string is like #ffffff (you should use simply f, as a result of # is optionally available). Additionally you’ll be able to present integers as properly, that is only a easy “overloaded” comfort init methodology.

Additionally .hexValue will return the string illustration of a UIColor occasion. 👏👏👏

Tips on how to generate a random UIColor in Swift?

That is additionally a quite common query for freshmen, I do not actually wish to waste the house right here by deep rationalization, arc4random() is simply doing it is job and the output is a pleasant randomly generated shade.

public extension UIColor {
    public static var random: UIColor {
        let max = CGFloat(UInt32.max)
        let crimson = CGFloat(arc4random()) / max
        let inexperienced = CGFloat(arc4random()) / max
        let blue = CGFloat(arc4random()) / max

        return UIColor(crimson: crimson, inexperienced: inexperienced, blue: blue, alpha: 1.0)
    }
}

Tips on how to create a 1×1 pixel large UIImage object with a single stable shade in Swift?

I am utilizing this trick to set the background shade of a UIButton object. The explanation for that is state administration. In case you press the button the background picture can be darker, so there can be a visible suggestions for the person. Nonetheless by setting the background shade instantly of a UIButton occasion will not work like this, and the colour will not change in any respect on the occasion. 👆

public extension UIColor {
    public var imageValue: UIImage {
        let rect = CGRect(origin: .zero, measurement: CGSize(width: 1, peak: 1))
        UIGraphicsBeginImageContext(rect.measurement)
        let context = UIGraphicsGetCurrentContext()!
        context.setFillColor(self.cgColor)
        context.fill(rect)
        let newImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return newImage!
    }
}

The snippet above will produce a 1×1 pixel picture object from the supply shade. You need to use that anywere, however right here is my instance with a button background:

button.setBackgroundImage(UIColor.crimson.imageValue, for: .regular)

On-line shade palettes

You possibly can’t discover the suitable shade? No drawback, these hyperlinks will assist you to to decide on the right one and to get some inspiration. Additionally in case you are searching for flat UI colours or materials design colours these are the suitable hyperlinks the place you need to head first.

A private factor of mine: pricey designers, please by no means ever attempt to use materials design rules for iOS apps. Thanks. HIG

Convert colours on-line

Lastly there are some nice on-line shade converter instruments, in case you are searching for a fantastic one, you need to strive these first.

Managing UIColors

In case your app goal is iOS 11+ you should use asset catalogs to prepare your shade palettes, but when it’s good to go beneath iOS 11, I might recommend to make use of an enum or struct with static UIColor properties. These days I am normally doing one thing like this.

class App {
    struct Coloration {
        static var inexperienced: UIColor { return UIColor(hex: 0x4cd964) }
        static var yellow: UIColor { return UIColor(hex: 0xffcc00) }
        static var crimson: UIColor { return UIColor(hex: 0xff3b30) }
    }

    
}

App.Coloration.yellow

Often I am grouping collectively fonts, colours and so on inside structs, however this is only one manner of doing issues. You can too use one thing like R.swift or something that you just want.

That is it for now, I believe I’ve coated many of the fundamental questions on UIColor.

Be at liberty to contact me if in case you have a subject or suggestion that you just’d wish to see coated right here within the weblog. I am at all times open for brand new concepts. 😉