Run closure of promise/future on main ui thread

[iliraga]

Is it possible to run the Promise-Closure on the main thread? Sometimes I want to perform a UI asynchronous operation like requesting permissions to user etc. If those are runned in separate threads, they are not shown to the user... I wasn't able to found any solution in documentation or sourcecode

[Yasuhiro Inami]

You can use any threading techniques e.g. Grand Central Dispatch inside Task initialization
to deliver fulfill/reject events on your target thread/queue.

Please see below as an example:

SwiftTask/Playgrounds/02-Async.playground/Contents.swift

Lines 25 to 33 in 16c08c0

 // fulfills after 100ms 
 func asyncTask(value: String) -> MyTask 
 { 
     return MyTask { progress, fulfill, reject, configure in 
         dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 100_000_000), dispatch_get_main_queue()) { 
             fulfill(value) 
         } 
     } 
 }