NumberUtilities.swift

import Foundation

extension Float {
    func format(f: String) -> String {
        return String(format: "%\(f)f", self)
    }
    mutating func roundTo(decimals: Int) {
        let divisor = pow(10.0, Float(decimals))
        self = round(self * divisor) / divisor
    }
    func roundTo(decimals: Int) -> Float {
        let divisor = pow(10.0, Float(decimals))
        return round(self * divisor) / divisor
    }
    func roundedUpString(decimals: Int) -> String {
        let divisor = pow(10.0, Float(decimals))
        var roundedNumber = "\(ceil(self * divisor) / divisor)"
        if roundedNumber.hasSuffix(".0") {
            roundedNumber.substringToIndex(find(roundedNumber, ".")!)
        }
        return roundedNumber
    }
    func descriptionWithLocale(locale: NSLocale) -> String? {
        return NSNumber(float: self).descriptionWithLocale(locale)
    }
}

extension Double {
    func format(f: String) -> String {
        return String(format: "%\(f)f", self)
    }
    mutating func roundTo(decimals: Int) {
        let divisor = pow(10.0, Double(decimals))
        self = round(self * divisor) / divisor
    }
    func roundTo(decimals: Int) -> Double {
        let divisor = pow(10.0, Double(decimals))
        return round(self * divisor) / divisor
    }
    func roundedUpString(decimals: Int) -> String {
        let divisor = pow(10.0, Double(decimals))
        var roundedNumber = "\(ceil(self * divisor) / divisor)"
        if roundedNumber.hasSuffix(".0") {
            roundedNumber.substringToIndex(find(roundedNumber, ".")!)
        }
        return roundedNumber
    }
    func descriptionWithLocale(locale: NSLocale) -> String? {
        return NSNumber(double: self).descriptionWithLocale(locale)
    }
}

extension Int {
    func descriptionWithLocale(locale: NSLocale) -> String? {
        return NSNumber(integer: self).descriptionWithLocale(locale)
    }
}