eneko / Sync

Run asynchronous blocks synchronously

Sync

Run asynchronous blocks synchronously

Installation

With cocoapods:

pod 'Sync'

Without cocoapods:

1. Grab the Sync.swift file form the Sources folder and add it to your project.

Or:

1. Clone the repo
2. Build the framework with archive
3. Add the Sync.framework bundle to your project

Usage

Similar to semaphores or dispatch_group, Sync mus be notified when the asynchronous block is complete. The asynchronous code can be running on a background thread:

let sync = Sync()
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)) {
    // Your async code in background thread
    sync.complete()
}
sync.wait()

...or in the main thread:

let sync = Sync()
dispatch_async(dispatch_get_main_queue()) {
    // Your async code in main thread
    sync.complete()
}
sync.wait()

Sync waits indefinitely for the block to complete unless a timeout is specified:

let sync = Sync()
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)) {
    // Your async code in background thread
    sync.complete()
}
sync.wait(seconds: 5) // wait at most 5 seconds and continue

Synchronous Methods

Sync works even in cases where the completion block is called on the main thread, avoiding a deadlock. This makes it very simple to write synchronous methods that can be run on a command line application or inside an NSOperation or background thread.

func locationForString(name: String) -> CLLocation? {
    var location: CLLocation?
    let sync = Sync()
    CLGeocoder().geocodeAddressString(name) { (placemarks, error) in
        location = placemarks?.first?.location
        sync.complete()
    }
    sync.wait(seconds: 5)
    return location
}

let location = locationForString("San Francisco")
print(location.coordinate)