Returning a Promise from a completion handler in PromiseKit

user_5429504 0
Viewed 1588

I have the following problem:

func doSomething() -> Promise<Bool> {

  let completionHandler = { (result: Bool) in
    // How can I fulfill the promise here -- Promise { fulfill, _ in fulfill(result) } 
  }

  someLibrary.doSomeTasks(handler: completionHandler)
  // What do I return for this function?...
}

Currently I don't know what to return / how to return a Promise<Bool> because the bool value isn't available until the completion handler is finished. someLibrary.doSomeTasks doesn't support PromiseKit so I'm stuck with using the completion handler like shown. Thanks!

promisekit promise swift asynchronous ios
2 Answers

this has been updated in promiseKit 6 to:

func doSomething() -> Promise<Bool> {
   return Promise<Bool> { seal in 
       someLibrary.doSomeTask(handler: { value in
           seal.fullfill(value)

           // we also have seal.reject(error), seal.resolve(value, error)
       })
   }
}
user_79994220

Here is the general form to do what you want:

func doSomething() -> Promise<Bool> {
    return Promise { fulfill, reject in 
        someLibrary.doSomeTask(handler: { value in
            fulfill(value)
        })
    }
}
user_5064410
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