Random Numbers in Swift

Random.swift

struct Random {
    static func within<B: protocol<Comparable, ForwardIndexType>>(range: ClosedInterval<B>) -> B {
    	let inclusiveDistance = range.start.distanceTo(range.end).successor()
    	let randomAdvance = B.Distance(arc4random_uniform(UInt32(inclusiveDistance.toIntMax())).toIntMax())
    	return range.start.advancedBy(randomAdvance)
    }
    
    static func within(range: ClosedInterval<Float>) -> Float {
        return (range.end - range.start) * Float(Float(arc4random()) / Float(UInt32.max)) + range.start
    }
    
    static func within(range: ClosedInterval<Double>) -> Double {
        return (range.end - range.start) * Double(Double(arc4random()) / Double(UInt32.max)) + range.start
    }
    
    static func generate() -> Int {
        return Random.within(0...1)
    }
    
    static func generate() -> Bool {
        return Random.generate() == 0
    }
    
    static func generate() -> Float {
        return Random.within(0.0...1.0)
    }
    
    static func generate() -> Double {
        return Random.within(0.0...1.0)
    }
}

// Example

while true { println(Random.within(2.3...5.7)) }
/* -> 2.98055791377103
 *    3.29764970182386
 *    3.46185294840528
 *    4.50507207708551
 *    4.7390977582054
 *    4.98469445493182
 *    3.17118956238758
 *    4.88981824288839
 *    4.35301200199244
 *    2.87590078748201
 *    5.20722583832853
 *    4.98944639761221
 *    3.90587487821604
 *    3.97134446820043
 *    2.6031687081566
 *    2.98006869556384
 *    2.9983296749411
 *    2.72558503174819
 *    2.30275103338127
 *    5.17898262280016
 *    ...
 */

Added a generate() for CGFloats at https://gist.github.com/tiktuk/1dd83e6cdd2fede38be7 ☺️ .