Pieter - 6 months ago 71

Swift Question

I am familiar with

`switch`

`switch`

`if someVar < 0 {`

// do something

} else if someVar == 0 {

// do something else

} else if someVar > 0 {

// etc

}

Answer

Here's one approach. Assuming `someVar`

is an `Int`

or other `Comparable`

, you can optionally assign the operand to a new variable. This lets you scope it however you want using the `where`

keyword:

```
var someVar = 3
switch someVar {
case let x where x < 0:
print("x is \(x)")
case let x where x == 0:
print("x is \(x)")
case let x where x > 0:
print("x is \(x)")
default:
print("this is impossible")
}
```

This can be simplified a bit:

```
switch someVar {
case _ where someVar < 0:
print("someVar is \(someVar)")
case 0:
print("someVar is 0")
case _ where someVar > 0:
print("someVar is \(someVar)")
default:
print("this is impossible")
}
```

You can also avoid the `where`

keyword entirely with range matching:

```
switch someVar {
case Int.min..<0:
print("someVar is \(someVar)")
case 0:
print("someVar is 0")
default:
print("someVar is \(someVar)")
}
```