Switch statement inside if statement - ios

Question

I am trying to have a switch statement inside of an if statement checking integers
if variable <= 3 {
// code
switch variable {
case 0:
println("0 case")
case 1:
println("1 case")
case 2:
println("2 case")
case 3:
println("3 case")
default:
println("error")
}
}
But I am getting an error for each case
Binary operator '~=' cannot be applied to operands of type 'Int' and 'Int?'
I do not understand why this wouldn't work.

Answer 1

3 is an Int but variable is an Int? (an optional Int). You have to unwrap it.
For example, you can check if it's nil in the if statement. If it's not, then it's safe to force-unwrap (with !) inside the scope of that conditional:
One of many possible approaches:
if variable <= 3 && variable != nil {
// code
switch variable! {
case 0:
println("0 case")
case 1:
println("1 case")
case 2:
println("2 case")
case 3:
println("3 case")
default:
println("error")
}
}

Answer 2

var variable : Int? will not work
var variable = 2
//var variable : Int? // will not work
if variable <= 3 {
// code
switch variable {
case 0:
println("0 case")
case 1:
println("1 case")
case 2:
println("2 case")
case 3:
println("3 case")
default:
println("error")
}
}

Answer 3

If your variable is an Optional, be aware that if it's nil then in your initial if statement the expression nil <= 3 returns true.
So, the most comprehensive form your can choose (IMHO) is:
var variable : Int? = ...
switch variable {
case .Some(0):
print("1 case")
case .Some(1):
print("2 case")
case .Some(3):
print("3 case")
case .Some(let x):
print("We got \(x)")
case .None:
print("variable is nil")
}
Note:
print is Swift 2.0. Use println in Swift 1.2