Nested functions in Swift

Question

I am learning swift and want to understand how to make nested functions

extension Auto {
    // MARK: Auto extensions
    func isRegistred() -> Bool {
        return true
    }
}

if I want to verify if an Auto is registered I have to use this line if Auto.isRegistered() If the auto is registered I also want to be able to verify if it's a new one, so I want to add a isNew() function. Is it possible to add a nested function so that I can still verify if the auto is registered with Auto.isRegistered() and use Auto.isRegistered().isNew() to verify that it's a registered auto and a new one? Something like

extension Auto {
    // MARK: Auto extensions
    func isRegistred() -> Bool {
        func isNew() -> Bool{
            return true
        }
        return true
    }
}

Tim Vermeulen · Accepted Answer · 2016-08-17 11:02:42Z

5

No, that wouldn't really make sense. You can't access functions within functions. auto.isRegistered() returns a Bool, so auto.isRegistered().isNew() would try to call the isNew() method on Bool which, obviously, doesn't exist.

I also advise you to use computed properties instead of functions if you name it "isSomething", that's more in line with Apple's APIs. So you'd get something like this:

extension Auto {
    var isRegistered: Bool {
        // ...
    }

    var isNew: Bool {
        // ...
    }
}

Then you can simply check if an auto is both registered and new with

auto.isRegistered && auto.isNew

edited Aug 17, 2016 at 11:02

answered Aug 17, 2016 at 9:45

Tim Vermeulen

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