fixup: Swift example takes arguments from CLI

Swift/fibonacci/fibonacci.swift

@@ -1,12 +1,31 @@
-func fibonacci(n: Int) -> Int {
-var a = 0
-var b = 1
-for _ in 0..<n {
-let temp = a
-a = b
-b = temp + b
-}
-return a
+func fib(n: UInt) -> UInt {
+	if n <= 1 {
+		return n
+	}
+
+	return fib(n: n-1) + fib(n: n-2)
 }
 
-print(fibonacci(n:7))
+let arguments = CommandLine.arguments
+
+var n:UInt
+if (arguments.count > 1) {
+	for i in 1...arguments.count-1 {
+		if let n = UInt(arguments[i]) {
+			print("Fibonacci sequence number at index \(n) is \(fib(n: n))")
+		} else {
+			print("Failed to parse argument into a number: \(arguments[i])\n")
+		}
+	}
+} else {
+	print("Enter a non-negative number:")
+	if let line = readLine() {
+		if let n = UInt(line) {
+			print("Fibonacci sequence number at index \(n) is \(fib(n: n))")
+		} else {
+			print("Could not convert \(line) to integer.\n")	
+		}
+	} else {
+		print("Could not read user input.\n")	
+	}
+}