Casting to Task without specifying generic type

[adrianhr91]

I'm trying to create a universal error handler for my application and to make matters even more complicated I'm using an event bus to pass a task around. I'm trying to do the following:

let apiTask = data.object as! Task // Option 1
let apiTask = data.object as! Task<AnyObject> // Option 2

apiTask!.continueWith { (task) in
    if(task.cancelled || task.faulted) {
        self.isInError = true
    } else {
        self.isInError = false
    }
}

Option 1 gives a compile time error saying the generic type TResut of Task cannot be inferred.
Option 2 causes a runtime error saying Task<SpecificType> cannot be caster to Task<AnyObject>

I have the same implementation in Java where it seems you don't need to specify the generic type so I appreciate this might be a language limitation rather than a library one. TResult could be potentially any type so I can't specify it in the method above. Is there any way to work around this?

[xxtesaxx]

Hello,
I'm completely new to Bolts and also a beginner in swift so maybe this might be completely wrong but wouldn't it be possible to create a struct or class called e. g. "MyTaskResult" to wrap your actual result?

I just gave it a quick try and it seems to work:

func printHelloWorld() {
    doSomething().continueWith() { task in
        print(task.result?.result)
    }
}

func doSomething() -> Task<MyResult> {
    let tcs = TaskCompletionSource<MyResult>()
    ...
    tcs.set(result: MyResult(result: "Hello World" as AnyObject))
    ...
    return tcs.task
}

struct MyResult {
    var result: AnyObject
}

Surely there is a better way of doing this but this, I think, could at least work somehow.

[appacea]

Hi. Any updates on this? I'm running into the same problem.

I'm porting my code from Objc to Swift and have a function like this:

(void) handleException:(BFTask*)task{}

converted to Swift:

func handleException(_ task: Task)()

In ObjC the input can be any BFTask but in Swift I get the "Task cannot be caster to Task" error mentioned above by @adrianhr91 .

@xxtesaxx solution is a smart approach but requires the use of AnyObject in the input rather than a specific type.

[appacea]

I ended up going a different route, by using an extension I can create a function in the Task Class that can be called from any generic Task. So instead of a function that takes a generic Task as input, I have a function that is a prototype of a generic Task.

extension Task{
func handleException()()
}

This way handleException() can be called on any Task

Hope that helps someone else.