swift中编程的十六进制颜色与主情节提要不同

let redColor = UIColor(red: 1.0, green: 0.0, blue: 0.0, alpha: 1.0)

extension UIColor {
    convenience init(hex: String) {
        var hexValue = hex.trimmingCharacters(in: CharacterSet.alphanumerics.inverted)
        if hexValue.count == 6 {
            hexValue = "FF" + hexValue
        }
        
        var rgbValue: UInt64 = 0
        Scanner(string: hexValue).scanHexInt64(&rgbValue)
        
        let red = CGFloat((rgbValue & 0xFF0000) >> 16) / 255.0
        let green = CGFloat((rgbValue & 0x00FF00) >> 8) / 255.0
        let blue = CGFloat(rgbValue & 0x0000FF) / 255.0
        
        self.init(red: red, green: green, blue: blue, alpha: 1.0)
    }
}

let redColor = UIColor(hex: "#FF0000")