RandomExtensions.swift

extension Float {
    static func randomFloat(range : ClosedInterval<Float>) -> Float {
        return range.start + (range.end - range.start) * Float(Float(arc4random()) / Float(UInt32.max))
    }
}
extension Int {
    static func randomInt(range : ClosedInterval<Int>) -> Int {
        return range.start + Int(arc4random_uniform(UInt32(range.end - range.start + 1)))
    }
}
extension Double {
    static func randomDouble(range : ClosedInterval<Double>) -> Double {
        return range.start + (range.end - range.start) * Double(Double(arc4random()) / Double(UInt32.max))
    }
}
extension String {
    static func randomString(length : Int) -> String {
        let characters : NSString = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
        var mutableString = NSMutableString(capacity: length)
        for var i = 0; i < length; i++ {
            mutableString.appendFormat("%C", characters.characterAtIndex(Int(arc4random_uniform(UInt32 (characters.length)))))
        }
        return mutableString
    }
}


Float.randomFloat(1.3...5.6) //Output -> 2.56939077377319
Int.randomInt(1...6) // Output -> 3
Double.randomDouble(1.6...9.8) //Output -> 3.9534583365902
String.randomString(10) // Output -> 5A2SZGEpwc