SWIFT开发extension
Extension
SWIFT编写和应用extension变得很简单。
直接在项目中增加UIColor+Extension.swift,就可以在其他文件中直接使用了。
例子:使用 #FFFFFF 或 #FFFFFFFF 来设置颜色值,快速与Web开发同步参数。
//
// UIColor+Extension.swift
//
import UIKit
extension UIColor {
public convenience init?(hex: String) {
let r, g, b, a: CGFloat
if hex.hasPrefix("#") {
let start = hex.index(hex.startIndex, offsetBy: 1)
let hexColor = String(hex[start...])
if hexColor.count == 8 {
let scanner = Scanner(string: hexColor)
var hexNumber: UInt64 = 0
if scanner.scanHexInt64(&hexNumber) {
r = CGFloat((hexNumber & 0xff000000) >> 24) / 255
g = CGFloat((hexNumber & 0x00ff0000) >> 16) / 255
b = CGFloat((hexNumber & 0x0000ff00) >> 8) / 255
a = CGFloat(hexNumber & 0x000000ff) / 255
self.init(red: r, green: g, blue: b, alpha: a)
return
}
}
if hexColor.count == 6 {
let scanner = Scanner(string: hexColor)
var hexNumber: UInt64 = 0
if scanner.scanHexInt64(&hexNumber) {
r = CGFloat((hexNumber & 0xff0000) >> 16) / 255
g = CGFloat((hexNumber & 0x00ff00) >> 8) / 255
b = CGFloat(hexNumber & 0x0000ff) / 255
self.init(red: r, green: g, blue: b, alpha: 255)
return
}
}
}
return nil
}
}
调用举例:
UIColoe.init(hex:"#FFFFFF")
UIColoe.init(hex:"#00000088") // 88 表示透明度 alpha