Upgrading to Swfit 3: cannot override 'init' which has been marked unavailable

Question

I just inherited an iOS project which incorporates Apple's ResearchKit (RK).

I have upgraded to the most recent version of RK and also to Swift 3. While I have worked in iOS and RK, I am still not very confident. Anyways, There is a class called SurveyTask which implements an ORKOrderedTask from RK.

cannot override 'init' which has been marked unavailable

at the end this function, stepz already defined, we have:

super.init(identifier: "survey", steps: stepz)

I checked the ORKOrderedTask class definition, which has an init function.

I have been reading about initializers but haven't found anything. Using override or convenience before the init in SurveyTask doesn't change anything. Same error. Any help would be greatly appreciated.

XCode version 8.1.

Answer 1

Here's how you can mimic a parameterless initializer and avoid the unavailable error:

class MyClass: ParentWithUnavailableInitializer {
    init(workaround _: Void = ()) {
        // Call a designated initializer
        super.init(param: "a very sensible value")
    }
}

// At a call site
let obj = MyClass()

Works in Swift 3.2 and Swift 4.