Allow setting the result of a task completion source from an existing task. about bolts-objc HOT 4 OPEN

import Bolts

extension BFTaskCompletionSource {

    func setTask(task: BFTask) {
        if task.faulted {
            if task.error != nil {
                setError(task.error)
            } else {
                setException(task.exception)
            }
        } else if task.cancelled {
            cancel()
        } else {
            setResult(task.result)
        }
    }
}

from bolts-objc.

cc @grantland What do you think?
Using updateFromTask: on a BFTaskCompletionSource actually makes slightly more sense, since we already have a task aka getTask property on it.

from bolts-objc.

First, when do we really need to use this pattern, how often do we need to use this pattern, and is it really something we se other developers utilizing? I'm not quite convinced this needs to be pushed upstream.

from bolts-objc.

This pattern is necessary when interacting with libraries that aren't designed with Bolts in mind. For example, Let's say I have an initialization task, followed by a NetworkTask where I create an NSURLSessionDataTask which has a completionHandler that has a few of sub-tasks to run which should eventually hit a FinalTask which is in charge of handling errors generated in all tasks above it as well as handling the success case if everything goes as planed.

InitTask
NetworkTask
network-subtaskA
network-subtaskB
FinalTask

If I didn't have a NetworkTask which had it's own completionHandler outside the scope of Bolts, I could do this simply by returning a task chain in the NetworkTask in the continueWith block which intelligently would determine the if the result returned is a BFTask handle it one way, else wrap the result in a BFTask and handle it another way.

In short the request here is to have the same ability when setting the results of a completionSource as we do when returning results from a continueWith block.

from bolts-objc.