swift 中常用的进制转换

import Foundation
extension Character
{
func toInt() -> Int
{
var intFromCharacter:Int = 0
for scalar in String(self).unicodeScalars
{
intFromCharacter = Int(scalar.value)
}
return intFromCharacter
}
}
//MARK: 十六进制 --> 十进制
func hex2dec(num:String) -> Int
{
let str = num.uppercaseString
var sum = 0
for i in str.utf8 {
sum = sum * 16 + Int(i) - 48 // 0-9 从48开始
if i >= 65 {                 // A-Z 从65开始，但有初始值10，所以应该是减去55
sum -= 7
}
}
return sum
}
//MARK:十进制  --> 十六进制
func dec2hex(num:Int) -> String {
return String(format: "%0X", num)
}
//MARK: 十进制 -> 二进制
func dec2bin(var number:Int) -> String {
var str = ""
while number > 0 {
str = "\(number % 2)" + str
number /= 2
}
return str
}
//MARK: 二进制  ->  十进制
func bin2dec(num:String) -> Int {
var sum = 0
for cc in num.characters
{
sum = sum * 2 + cc.toInt()
}
return sum
}