Forked from user jstn. I have added extensions to CGFloat, CGPoint and Bool.

Random.swift

import Darwin

public func arc4random <T: IntegerLiteralConvertible> (type: T.Type) -> T {
    var r: T = 0
    arc4random_buf(&r, Int(sizeof(T)))
    return r
}

public extension UInt {
    public static func random(lower: UInt = min, upper: UInt = max) -> UInt {
        switch (__WORDSIZE) {
            case 32: return UInt(UInt32.random(lower: UInt32(lower), upper: UInt32(upper)))
            case 64: return UInt(UInt64.random(lower: UInt64(lower), upper: UInt64(upper)))
            default: return lower
        }
    }
}

public extension Int {
    public static func random(lower: Int = min, upper: Int = max) -> Int {
        switch (__WORDSIZE) {
            case 32: return Int(Int32.random(lower: Int32(lower), upper: Int32(upper)))
            case 64: return Int(Int64.random(lower: Int64(lower), upper: Int64(upper)))
            default: return lower
        }
    }
     public static func random(range: Range<Int>) -> Int {
        switch (__WORDSIZE) {
        case 32: return Int(Int32.random(lower: Int32(range.startIndex), upper: Int32(range.endIndex)))
        case 64: return Int(Int64.random(lower: Int64(range.startIndex), upper: Int64(range.endIndex)))
        default: return range.startIndex
        }
    }

}

public extension UInt32 {
    public static func random(lower: UInt32 = min, upper: UInt32 = max) -> UInt32 {
        return arc4random_uniform(upper - lower) + lower
    }
}

public extension Int32 {
    public static func random(lower: Int32 = min, upper: Int32 = max) -> Int32 {
        let r = arc4random_uniform(UInt32(Int64(upper) - Int64(lower)))
        return Int32(Int64(r) + Int64(lower))
    }
}

public extension UInt64 {
    public static func random(lower: UInt64 = min, upper: UInt64 = max) -> UInt64 {
        var m: UInt64
        let u = upper - lower
        var r = arc4random(UInt64)

        if u > UInt64(Int64.max) {
            m = 1 + ~u
        } else {
            m = ((max - (u * 2)) + 1) % u
        }

        while r < m {
            r = arc4random(UInt64)
        }

        return (r % u) + lower
    }
}

public extension Int64 {
    public static func random(lower: Int64 = min, upper: Int64 = max) -> Int64 {
        let (s, overflow) = Int64.subtractWithOverflow(upper, lower)
        let u = overflow ? UInt64.max - UInt64(~s) : UInt64(s)
        let r = UInt64.random(upper: u)

        if r > UInt64(Int64.max)  {
            return Int64(r - (UInt64(~lower) + 1))
        } else {
            return Int64(r) + lower
        }
    }
}

public extension Float {
    public static func random(lower: Float = 0.0, upper: Float = 1.0) -> Float {
        let r = Float(arc4random(UInt32)) / Float(UInt32.max)
        return (r * (upper - lower)) + lower
    }
}

public extension Double {
    public static func random(lower: Double = 0.0, upper: Double = 1.0) -> Double {
        let r = Double(arc4random(UInt64)) / Double(UInt64.max)
        return (r * (upper - lower)) + lower
    }
}
public extension CGFloat {
    public static func random(lower: CGFloat = 0.0, upper: CGFloat = 1.0) -> CGFloat
    {
        switch (__WORDSIZE) {
        case 32:
        let r = CGFloat(arc4random(UInt32)) / CGFloat(UInt32.max)
        return (r * (max - min)) + min
        case 64:
        let r = CGFloat(arc4random(UInt64)) / CGFloat(UInt64.max)
        return (r * (max - min)) + min
        default: return min
        }

    }
}
public extension CGPoint {
    
    public static func randomWithinCGRect(rectangle:CGRect) -> CGPoint
    {
        let x = CGFloat.random(min: rectangle.minX, max: rectangle.maxX)
        let y = CGFloat.random(min: rectangle.minY, max: rectangle.maxY)
        
        return CGPointMake(x,y)
    }
    public static func randomWithinCGSize(size:CGSize) -> CGPoint
    {
        let x = CGFloat.random(min: 0.0, max: size.width)
        let y = CGFloat.random(min: 0.0, max: size.height)
        
        return CGPointMake(x, y)
    }
    public static func random(minX: CGFloat, maxX: CGFloat, minY: CGFloat, maxY: CGFloat) -> CGPoint
    {
        return CGPoint.randomWithinCGRect(CGRectMake(minX, minY, maxX-minX, maxY-minY))
    }
    public static func random(WithinRadius radius:CGFloat, OfPoint midPoint:CGPoint) -> CGPoint
    {
        let r = CGFloat.random(min: 0.0, max: radius)
        let a = CGFloat.random(min: 0.0, max: CGFloat(M_PI * 2))
        let x = midPoint.x + r * cos(a)
        let y = midPoint.y + r * sin(a)
        return CGPointMake(x,y)
    }

}
public extension Bool {

    /**
        Random bool. 

        :returns: A random Bool.

    */
    public static func random() -> Bool
    {
        return Double.random() <= 0.5
    }
    
    /**
        Random boolean with likeliness percentage parameter. An argument of 0.3 will return true ≈30% of the times the function is called.
        
        :param: likeliness Likeliness percentage expressed as a decimal between 0.0-1.0. 0.1 == 10% etc.
        :returns: A random Bool.
    */
    public static func randomWithLikeliness(likeliness: Double) -> Bool
    {
        assert(likeliness > 0.0 && likeliness <= 1.0, "Likeliness percentage must be expressed with a value between 0.0 - 1.0")
        return Double.random() <= likeliness
    }
}

Usage instructions

//Int

let randomInt = Int.random(1...10) 
let randomInt = Int.random(lower:1, upper:10)

//Double, Float, CGFloat  
let randomDouble = Double.random() // Random between 0.0-1.0
let randomDouble = Double.random(lower:2.0, upper:5.0)

//CGPoint
let randomPoint = CGPoint.random(minX:5.0, maxX:10.0, minY:20.0, maxY:30.0)
let randomPoint = CGPoint.randomWithinCGRect(rectangle)
let randomPoint = CGPoint.randomWithinCGSize(size)
let randomPoint = CGPoint.random(WithinRadius:40.0, OfPoint:point) //Random point within circle

//Bool
let randomBool = Bool.random() //Random true or false
let randomBool = Bool.randomWithLikeliness(0.3) // True in approx 30% of the cases