SubString using Int instead of StringIndex Type

gistfile1.swift

extension String{
    func substringFromIndexInt(indx:Int) -> String {
        let index = advance(self.startIndex, indx)
        return self.substringFromIndex(index)
    }

    func substringWithRangeInt(intRange:Range<Int>)->String{
        let start = advance(self.startIndex,intRange.startIndex)
        let end = advance(self.startIndex,intRange.endIndex)
        return self.substringWithRange(start..<end)
    }
    
    
}