An alternative to if let
is guard let
, which also unwraps optionals. guard let
will unwrap an optional for you, but if it finds nil
inside it expects you to exit the function, loop, or condition you used it in.
However, the major difference between if let
and guard let
is that your unwrapped optional remains usable after the guard
code.
Let’s try it out with a greet()
function. This will accept an optional string as its only parameter and try to unwrap it, but if there’s nothing inside it will print a message and exit. Because optionals unwrapped using guard let
stay around after the guard
finishes, we can print the unwrapped string at the end of the function:
func greet(_ name: String?) {
guard let unwrapped = name else {
print("You didn't provide a name!")
return
}
print("Hello, \(unwrapped)!")
}
Using guard let
lets you deal with problems at the start of your functions, then exit immediately. This means the rest of your function is the happy path – the path your code takes if everything is correct.
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