Dictionary to go from a String like "ff" to a UInt8 like 255

dictionaryBytesToInts.swift

func dictionaryBytesToInts() -> [String:UInt8] {
    var D: [String:UInt8] = [:]
    let chars = "0123456789abcdef".characters.map { String($0) }
    for k1 in chars {
        for k2 in chars {
            let i = chars.indexOf(k1)!
            let j = chars.indexOf(k2)!
            D[k1+k2] = UInt8(i*16 + j)
        }
    }
    return D
}