Use the guard keyword for early returns
Use the guard keyword for early returns 관련
Available from Swift 2.0
It's very common to place some conditional checks at the start of a method to ensure that various data is configured ready to go. For example, if a Submit button is tapped, you might want to check that the user has entered a username in your user interface. To do this, you'd use this code:
func submitTapped() {
guard username.text.characters.count > 0 else {
return
}
print("All good")
}
Using guard might not seem much different to using if, but with guard your intention is clearer: execution should not continue if your conditions are not met. Plus it has the advantage of being shorter and more readable, so guard is a real improvement, and I'm sure it will be adopted quickly.
There is one bonus to using guard that might make it even more useful to you: if you use it to unwrap any optionals, those unwrapped values stay around for you to use in the rest of your code block. For example:
guard let unwrappedName = userName else {
return
}
print("Your username is \(unwrappedName)")
This is in comparison to a straight if statement, where the unwrapped value would be available only inside the if block, like this:
if let unwrappedName = userName {
print("Your username is \(unwrappedName)")
} else {
return
}
// this won't work – unwrappedName doesn't exist here!
print("Your username is \(unwrappedName)")
Other changes in Swift 2.0…