Swift NSString to Int conversion issues - swift

Question

First off, I'm fairly new to programming and trying to learn Swift, though I've worked with python and perl in the past.
I'm creating a simple prime number command line application. The program runs correctly when I provide the arguments for the functions, but causes consistently incorrect outputs when I prompt user input. I researched the best way to implement this behavior in Swift, as it doesn't have scanf() or raw_input() type commands, but I have something screwed up.
The program has several different functions, but the one I've been fighting with checks whether an integer is prime. The code for the function follows:
func testForPrime(num:Int)->Bool{
var num = num
var counter = 0
var primeTest : Bool = true
if num <= 1 || num % 2 == 0{
println("\(num) is not a prime number")
primeTest = false
}else{
##'checkerNumbers' is another function to determine the denominator
for i in checkerNumbers(Double(num)){
if num % i == 0 {
++counter
println("\(num) is not a prime number.")
println("\(num / i)*\(i)=\(num)")
primeTest = false
break
}
}
if counter == 0{
println("\(num) is a prime number!")
primeTest = true
}
}
return primeTest
}
And here is the input for the function:
var input = NSFileHandle.fileHandleWithStandardInput()
println("Enter a number to check if it is prime")
if let data : NSData = input.availableData as NSData? {
if let var x : Int = NSInteger(NSUTF8StringEncoding) as NSInteger?{
var intInput = x
testForPrime(intInput)
}
}
When a any number is entered in the terminal, the output is always '4'. However, if I run the function with testForPrime(13), instead of with user input, it responds as I would expect. I was thinking it may have to do with the conversion from NSString and NSUTF8StringEncoding to Int...
Can someone help me sort this out?
Thanks in advance!

Answer 1

Ok... So I figured out a way to make it work, though it may not be the best. I replaced the whole input section with the following:
println("Enter a number to check if it is prime")
var input = NSString(data: NSFileHandle.fileHandleWithStandardInput().availableData, encoding:NSUTF8StringEncoding)
var intInput = input?.intValue
testForPrime(Int(intInput!))