How to create a string with format?

Question

I need to create a string with format which can convert int, long, double etc. types into string. Using Obj-C, I can do it via below way.

NSString *str = [NS         


        

Answer 1

Success to try it:

 var letters:NSString = "abcdefghijkl"
        var strRendom = NSMutableString.stringWithCapacity(strlength)
        for var i=0; i, <#CVarArg[]#>)
            let strlk = NSString(format: "%c", letters.characterAtIndex(rndString))
            strRendom.appendString(String(strlk))
        }