When can the "default" be ommited in a Switch statement?

Question

In the "Conditional Statement" part of the tutorial it shows this piece of code to explain the "where" command:
let myPoint = (1, -1)
switch myPoint {
case let (x, y) where x == y:
print("(\(x), \(y)) is on the line x == y")
case let (x, y) where x == -y:
print("(\(x), \(y)) is on the line x == -y")
case let (x, y):
print("(\(x), \(y)) is just some arbitrary point")
}

It has no "default" case.
If I change the pairs of values for an Int:
let Input = 500
switch Input {
case let (x) where x <= 50:
print ("in case a")
case let (x) where x > 50:
print ("in case b")
}

It gives me an error asking for a default value...

Can someone please explain me why is that?

Answer 1

the default statement can be omitted only if all the possible cases are covered in the switch...case statement, otherwise it is always good to put a default statement to be executed in case the user inputs are not covered by any of the other case statement s

Answer 2

Hi Ramzi, thanks for your answer.
But I still don't see, why I'm getting the error in this code:

let Input = 500
switch Input {
case let (x) where x <= 50:
print ("in case a")
case let (x) where x > 50:
print ("in case b")
}

I mean, all possible cases are consider in these two case, right? In that case, why is still no ok?
Thanks in advance.

Answer 3

I haven't never programmed with swift before but reviewing your code I think that you should add another line :
case let (x):
print ("not in any case")

hope it helps
thanks