Is there a way to do conditional assignment to constants in Swift?
You could also do this
var someConstant: String {
if #available(iOS 9, *) {
return "iOS 9"
} else {
return "not iOS 9"
}
}
By doing this you can't assign a value to the variable someConstant
even if it is a var
and not a let
because it is a calculated property
Another way of doing this would be to use free functions.
let someConstant: String = {
if #available(iOS 9, *) {
return "iOS 9"
} else {
return "not iOS 9"
}
}()
The difference between the first example from the second example is that the second example is only instantiated once.
Do the declaration and assignment on two separate lines:
let attribs: [NSAttributedString.Key: Any]
if #available(iOS 8.2, *) {
attribs = [.font: UIFont.systemFont(ofSize: 30, weight: .light)]
} else {
attribs = [.font: UIFont.systemFont(ofSize: 30)]
}
Even though it is a let
, you can do the assignment (only once per path of execution) on a separate line.
I think you want something like this:
let value: String
if #available(iOS 9, *) {
value = "iOS 9 is available"
} else {
value = "iOS 9 and up only"
}
print(value) // iOS 9 is available