gistfile1.swift

import Foundation


extension String {
    
    func numsToCharsA() -> String {
        return self.stringByReplacingOccurrencesOfString("1", withString: "a")
                .stringByReplacingOccurrencesOfString("2", withString: "b")
                .stringByReplacingOccurrencesOfString("3", withString: "c")
                .stringByReplacingOccurrencesOfString("4", withString: "d")
                .stringByReplacingOccurrencesOfString("5", withString: "e")
                .stringByReplacingOccurrencesOfString("6", withString: "f")
                .stringByReplacingOccurrencesOfString("7", withString: "g")
                .stringByReplacingOccurrencesOfString("8", withString: "h")
                .stringByReplacingOccurrencesOfString("9", withString: "i")
    }
    
    func numsToCharsB() -> String {
        let table = [
            "1":"a",
            "2":"b",
            "3":"c",
            "4":"d",
            "5":"e",
            "6":"f",
            "7":"g",
            "8":"h",
            "9":"i"
        ]
        
        var newStr = self
        for (key, value) in table {
            print("value: \(value), key: \(key)")
            newStr = newStr.stringByReplacingOccurrencesOfString(key, withString: value)
        }
        
        return newStr
    }
    
}