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@yannickl
Last active September 16, 2023 03:55
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Hex string <=> UIColor conversion in Swift
import Foundation
import UIKit
extension UIColor {
convenience init(hexString:String) {
let hexString:NSString = hexString.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet())
let scanner = NSScanner(string: hexString)
if (hexString.hasPrefix("#")) {
scanner.scanLocation = 1
}
var color:UInt32 = 0
scanner.scanHexInt(&color)
let mask = 0x000000FF
let r = Int(color >> 16) & mask
let g = Int(color >> 8) & mask
let b = Int(color) & mask
let red = CGFloat(r) / 255.0
let green = CGFloat(g) / 255.0
let blue = CGFloat(b) / 255.0
self.init(red:red, green:green, blue:blue, alpha:1)
}
func toHexString() -> String {
var r:CGFloat = 0
var g:CGFloat = 0
var b:CGFloat = 0
var a:CGFloat = 0
getRed(&r, green: &g, blue: &b, alpha: &a)
let rgb:Int = (Int)(r*255)<<16 | (Int)(g*255)<<8 | (Int)(b*255)<<0
return NSString(format:"#%06x", rgb)
}
}
@ucotta
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ucotta commented Mar 14, 2018

A simplified version of eMdOS with Alpha support and optionals. I use it to get the colors from a JSON without worrying if it's defined or not.

extension UIColor {
    convenience init?(hexRGBA: String?) {
        guard let rgba = hexRGBA, let val = Int(rgba.replacingOccurrences(of: "#", with: ""), radix: 16) else {
            return nil
        }
        self.init(red: CGFloat((val >> 24) & 0xff) / 255.0, green: CGFloat((val >> 16) & 0xff) / 255.0, blue: CGFloat((val >> 8) & 0xff) / 255.0, alpha: CGFloat(val & 0xff) / 255.0)
    }
    convenience init?(hexRGB: String?) {
        guard let rgb = hexRGB else {
            return nil
        }
        self.init(hexRGBA: rgb + "ff") // Add alpha = 1.0
    }
}

Usage:

let newColorWithAlpha = UIColor(hexRGBA: "#aabbccdd") ?? UIColor.white
let otherColor = UIColor(hexRGB: "#aabbcc") ?? UIColor.blue

@pvroosendaal
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