swift 中 UIColor 的一个简单扩展 UIColor+Extension

完整代码

import Foundation
import UIKit

extension UIColor {
convenience init(r : CGFloat, g : CGFloat, b : CGFloat){
self.init(red: r/255.0, green: g/255.0, blue: b/255.0, alpha: 1.0);
}
//简化RGB颜色写法
class func RGBA(_ r : UInt, g : UInt, b : UInt, a : CGFloat) -> UIColor {
let redFloat = CGFloat(r) / 255.0
let green = CGFloat(g) / 255.0
let blue = CGFloat(b) / 255.0
return UIColor(red: redFloat, green: green, blue: blue, alpha: a)
}
//随机色
class func randomColor() -> UIColor {
return UIColor(r: CGFloat(arc4random_uniform(256)), g: CGFloat(arc4random_uniform(256)), b: CGFloat(arc4random_uniform(256)));
}
//16进制颜色
class func colorWithHexString(_ hex: String, alpha : CGFloat = 1.0) -> UIColor {
var hex = hex
if hex.hasPrefix("#") {
hex = hex.substring(from: hex.characters.index(hex.startIndex, offsetBy: 1))
}

// Deal with 3 character Hex strings
if hex.characters.count == 3 {
let redHex = hex.substring(to: hex.characters.index(hex.startIndex, offsetBy: 1))
let greenHex = hex.substring(with: (hex.characters.index(hex.startIndex, offsetBy: 1) ..< hex.characters.index(hex.startIndex, offsetBy: 2)))
let blueHex = hex.substring(from: hex.characters.index(hex.startIndex, offsetBy: 2))

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

let redHex = hex.substring(to: hex.characters.index(hex.startIndex, offsetBy: 2))
let greenHex = hex.substring(with: (hex.characters.index(hex.startIndex, offsetBy: 2) ..< hex.characters.index(hex.startIndex, offsetBy: 4)))
let blueHex = hex.substring(with: (hex.characters.index(hex.startIndex, offsetBy: 4) ..< hex.characters.index(hex.startIndex, offsetBy: 6)))

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)

return UIColor(red: CGFloat(redInt) / 255.0, green: CGFloat(greenInt) / 255.0, blue: CGFloat(blueInt) / 255.0, alpha: CGFloat(alpha))
}
}

使用举例

RGBA

tableView.backgroundColor = UIColor.RGBA(53, g: 46, b: 54, a: 1)
十六进制颜色
self.tabBarController?.tabBar.barTintColor = UIColor.colorWithHexString("#252122")