Swift: Overriding a convenience with a designated initializer

Question

The Swift documentation states the following: If the initializer you are overriding is a convenience initializer, your override must call another designated initializer from its own subclass, as per the rules described above in Initializer Chaining. This means, that when I define an initializer with the same signature as a `convenience` initializer from the base class, then it must also act as a `convenience` initializer. I cannot "override" a `convenience` initializer with a `designated` initializer. This seems awkward to me: There might be various cases where a signature, e.g., `(String)` is only a convenience init for the base class but a designated init for a subclass. In contrast to methods, only because two initializer have the same signature, they do not have to perform a similar task. A signature of `(String)` could mean something completely different for a subclass. - So, why did they add this restriction? - How can I circumvent it? I.e., if I do need a non-convenience initia…

Accepted Answer

What they mean is that if the initialiser that you have after overriding is a convenience initialiser, then you must follow Initialiser Chaining.

The following works fine meaning you can override a convenience initialiser with a designated initialiser :

```
class Base {
    var x = 0
    init() {}
    convenience init(_: Int) {
        self.init()
        self.x = 5
    }
}

class Derived : Base {
    init() {}
    init(_: Int) {
        super.init()
        self.x = 10
    }
}

var i = Derived(1)     // x = 10
```

Swift: Overriding a convenience with a designated initializer

Solution

Problem