Alternative to implicitly unwrapped optional using @propertyWrapper in swift

Question

I found myself using a lot of implicitly unwrapped optionals when initialiser injection would not work or when creating mvvm modules for examples:

class TodoView: UIViewController {
    
    var viewModel: TodoViewModelProtocol!

}

Not only it doesn't look so good, but its also a pain to always force unwrap if I need to use a switch statement on an explicitly unwrapped optional variable for example.

Is there any way to get rid of the implicitly unwrapped optional, for example using @properyWrapper in swift 5?

Answer 1

You can simulate implicitly unwrapped optionals with a property wrapper as follows:

@propertyWrapper
struct MaybeUninitialized<T> {
    private var storage: T?
    var wrappedValue: T {
    get { storage! }
    set { storage = newValue}
    }
}

Then you can even use possibly uninitialized fields storing optionals without accidentially unwrapping the optional. Something like this:

@MaybeUninitialized var x: Int?

print(x) // will crash
x = nil
print(x) // print nil