How do I pick the color in hexadecimal form or RGB

问题:

This question already has an answer here:

• How to use hex color values 32 answers

I am trying to change the background color of TopScoreContainer to a lighter shade of green. I do not want to use greenColor() . Here is the line of code:

self.TopScoreContainer.backgroundColor = UIColor.greenColor()    

Is it possible to substitute in a hexadecimal number or RGB value instead of greenColor() ? Thanks.

回答1:

    let myCustomColorHSBa = UIColor(hue: 120/360, saturation: 0.25 , brightness: 1.0 , alpha: 1)
    let myCustomColorRGBa = UIColor(red: 191/255, green: 1, blue: 191/255, alpha: 1)

using it as an extension read-only computed var:

Read-Only Computed Properties

A computed property with a getter but no setter is known as a read-only computed property. A read-only computed property always returns a value, and can be accessed through dot syntax, but cannot be set to a different value.

NOTE

You must declare computed properties—including read-only computed properties—as variable properties with the var keyword, because their value is not fixed. The let keyword is only used for constant properties, to indicate that their values cannot be changed once they are set as part of instance initialization.

You can simplify the declaration of a read-only computed property by removing the get keyword and its braces:

extension UIColor {
    var lightGreen: UIColor {
        return UIColor(red: 191/255, green: 1, blue: 191/255, alpha: 1)
    }
}
let lightGreen = UIColor().lightGreen

or you can also create your own htmlColor input as follow:

update: Xcode 7.2 • Swift 2.1.1

extension String {
    subscript(range: Range<Int>) -> String {
        return range.startIndex < 0 || range.endIndex > characters.count ? "Out of Range" : substringWithRange(Range(start: startIndex.advancedBy(range.startIndex),end: startIndex.advancedBy(range.endIndex)))
    }
    var hexaCGFloat: CGFloat {
        return CGFloat(strtoul(self, nil, 16))
    }
}

extension UIColor {
    convenience init(htmlColor: String, alpha: Double) {
        self.init(red: htmlColor[1...2].hexaCGFloat / 255.0, green: htmlColor[3...4].hexaCGFloat / 255.0, blue: htmlColor[5...6].hexaCGFloat / 255.0, alpha: CGFloat(alpha)  )
    }
    convenience init(r: Int, g:Int , b:Int , a: Int) {
        self.init(red: CGFloat(r)/255, green: CGFloat(g)/255, blue: CGFloat(b)/255, alpha: CGFloat(a)/255)
    }
}
let myColor = UIColor(r: 255 , g: 0, b: 0, a: 255)
let myHtmlWebColor = UIColor(htmlColor: "#bfffbf", alpha: 1.0)