String Extension - Ordinal number formatting

gistfile1.swift

extension String {
    
    static func ordinalNumberFormat(number: Int) -> String {
        var ending = "th"
        
        let ones = number % 10
        let tens = ((number / 10) % 10) as Int
        
        if tens != 1 { // tens == 1 will always end in "th"
            switch ones {
            case 1:
                ending = "st"
            case 2:
                ending = "nd"
            case 3:
                ending = "rd"
            default:
                println("String.ordinalNumberFormat(\(number)) defaulting to \(ending)")
            }
        }
        
        return "\(number)\(ending)"
    }
    
}