Optional strings might contain a string like “Hello” or they might be nil – nothing at all.
Consider this optional string:
var name: String? = nil
What happens if we use name.count
? A real string has a count
property that stores how many letters it has, but this is nil
– it’s empty memory, not a string, so it doesn’t have a count
.
Because of this, trying to read name.count
is unsafe and Swift won’t allow it. Instead, we must look inside the optional and see what’s there – a process known as unwrapping.
A common way of unwrapping optionals is with if let
syntax, which unwraps with a condition. If there was a value inside the optional then you can use it, but if there wasn’t the condition fails.
For example:
if let unwrapped = name {
print("\(unwrapped.count) letters")
} else {
print("Missing name.")
}
If name
holds a string, it will be put inside unwrapped
as a regular String
and we can read its count
property inside the condition. Alternatively, if name
is empty, the else
code will be run.
SAVE 50% To celebrate WWDC23, all our books and bundles are half price, so you can take your Swift knowledge further without spending big! Get the Swift Power Pack to build your iOS career faster, get the Swift Platform Pack to builds apps for macOS, watchOS, and beyond, or get the Swift Plus Pack to learn advanced design patterns, testing skills, and more.
Link copied to your pasteboard.