struct Dog {
    var name: String
    init?(name: String) {
        guard name == "Lassie" else { //error message when "guard let": Pattern matching in a condition requires the 'case' keyword
            print("Sorry, wrong dog!")
            return nil
        }
        self.name = name
    }
}
let dog = Dog(name: "Fido")

Hi, how come the guard works without the "let" keyword and does not work with "guard let"? i thought its always "guard let" but seems not true for some reason..

Ok, thanks @roosterboy. guard let is to check if optional value exists or is nil and guard is just to check if condition is true or false.

I modified code to make initialiser with optional parameter to use guard let first and then when its true, jump to guard statement to check condition.

struct DogOptional {
    var name: String?
    init?(nameOptional: String?) {
        guard let unwrapped = nameOptional else { //guard with let because parameter is optional.
            print("Sorry, entry not received!")
            return nil
        }
        guard unwrapped != "Lassie" else{
            print("Sorry, wrong dog name!")
            return nil
        }
        self.name = unwrapped
        print("Dog name is: \(name!)")
    }
}
let dogObj = DogOptional(nameOptional: "Lassie")

And just as an FYI, you can often combine these two into onne guard:

        guard let unwrapped = nameOptional,  unwrapped != "Lassie" else {
            return nil
        }

Not in your specific example, if you want to maintain two separate error messages, but just be aware that it's possible.

Thanks @roosterboy for showing how to shorten the code by putting the 2 conditions into one line :D