Calculate Screen Ratios.

calcScreenRatios.swift

// Euclidean algorithm for GCD
func euclid( a:Int, b:Int ) -> Int{
	var aa : Int = a
	var bb : Int = b
	var rr : Int = aa % bb
	while rr != 0 {
		aa = bb
		bb = rr
		rr = aa % bb
	}
	return bb
}

func calcRatio( a:Int, b:Int ) -> ( ra:Int, rb:Int ){
	let gcd : Int = euclid(a, b)
	return (a/gcd, b/gcd)
}

func printRatio( a:Int, b:Int, memo:String? = nil ){
	let ratio = calcRatio(a, b)
	let prefex = (memo != nil) ? "\(memo!) : " : ""
	println("\(prefex)[\(a):\(b)] => [\(ratio.0):\(ratio.1)](\(Float(ratio.0)/Float(ratio.1)))")
}

// iPhone Screen Ratios
printRatio(640, 960, memo:"iPhone 4 (S)")	// [2:3](0.666666686534882)
printRatio(640, 1136, memo:"iPhone 5 (C|S)")	// [40:71](0.563380300998688)
printRatio(750, 1334, memo:"iPhone 6")		// [375:667](0.562218904495239)
printRatio(1080, 1920, memo:"iPhone 6 Plus")	// [9:16](0.5625)
printRatio(1536, 2048, memo:"iPad (all)")	// [3:4](0.75)