mainThread VS mainQueue #3
Description
There are quite a few checks like NSThread.isMainThread() in the code. Maybe this should be changed to checking for the main queue instead?
Here's sample code to check for the queue instead, based on http://blog.benjamin-encz.de/post/main-queue-vs-main-thread/, where the difference is explained, too:
private let mainQueueKey = UnsafeMutablePointer<Void>.alloc(1)
private let mainQueueValue = UnsafeMutablePointer<Void>.alloc(1)
// Associate a key-value pair with the main queue
dispatch_queue_set_specific(
dispatch_get_main_queue(),
mainQueueKey,
mainQueueValue,
nil
)
func dispatch_ensure_main_queue(block: dispatch_block_t) {
// Check for presence of key-value pair on current queue
if (dispatch_get_specific(mainQueueKey) == mainQueueValue) {
// if we found right value for key, execute immediately
print("main queue")
block()
} else {
// otherwise dispatch on main queue now
// /!\ Use dispatch_sync cautiously
// it can cause deadlocks!
dispatch_sync(dispatch_get_main_queue()) {
print("not main queue")
block()
}
}
return image
}