Swift: Nil is incompatible with return type String

Question

I have this code in Swift:

guard let user = username else{
        return nil
    }

But I'm getting the following errors:

Nil is incompatible with return type String

Any of you knows why or how I return nil in this case?

I'll really appreciate your help

Answer 1

You have to tell the compiler that you want to return nil. How do you that? By assigning ? after your object. For instance, take a look at this code:

func newFriend(friendDictionary: [String : String]) -> Friend? {
    guard let name = friendDictionary["name"], let age = friendDictionary["age"] else {
        return nil
    }
    let address = friendDictionary["address"]
    return Friend(name: name, age: age, address: address)
}

Notice how I needed to tell the compiler that my object Friend, which I'm returning, is an optional Friend?. Otherwise it will throw an error.