nsoperation

I'm trying to build a bulk image downloader, where images can be added to a queue on the fly to be downloaded, and I can find out the progress and when they're done downloading. Through my reading it seems like NSOperationQueue for the queue functionality and NSURLSession for the network functionality seems like my best bet, but I'm confused as to how to use the two in tandem. I know I add instances of NSOperation to the NSOperationQueue and they get queued. And it seems I create a download task with NSURLSessionDownloadTask , and multiple if I need multiple tasks, but I'm not sure how I put

Today I've met one weird issue when I was trying to 'generalize' my 'CoreData importing operations'. It appeared that if I create a generic subclass of NSOperation the main() func won't be called. Simple example: class MyOperation<T: NSObject>: NSOperation { override func main() { println("My operation main was called") } } If you create an instance of this class and add it to the operationQueue you will see that it's main() isn't actually called. override func viewDidLoad() { super.viewDidLoad() // Do any additional setup after loading the view, typically from a nib. self.operationQueue =

I am trying to get started with using Operation s in a side project rather than having closure-based callbacks littered throughout my networking code to help eliminate nested calls. So I was doing some reading on the subject, and I came across this implementation: open class AsynchronousOperation: Operation { // MARK: - Properties private let stateQueue = DispatchQueue(label: "asynchronous.operation.state", attributes: .concurrent) private var rawState = OperationState.ready private dynamic var state: OperationState { get { return stateQueue.sync(execute: { rawState }) } set { willChangeValue

I have a long running loop I want to run in the background with an NSOperation . I'd like to use a block: NSBlockOperation *operation = [NSBlockOperation blockOperationWithBlock:^{ while(/* not canceled*/){ //do something... } }]; The question is, how to I check to see if it's canceled. The block doesn't take any arguments, and operation is nil at the time it's captured by the block. Is there no way to cancel block operations? Doh. Dear future googlers: of course operation is nil when copied by the block, but it doesn't have to be copied. It can be qualified with __block like so: //THIS MIGHT

I've been wondering, can you use cancel/cancelAllOperations/.isCancelled with a thread you have launched with GCD? Currently, I just use a boolean as a flag, to cancel the background process. Let's say you want to do a lot of processing in the background, while keeping the UI responsive so that you can catch a cancel button (or animate something to show the processor is working). Here's how we do it... @interface AstoundingView : UIView { BOOL pleaseAbandonYourEfforts; blah } @implementation AstoundingView // // these are the foreground routines... // begin, abandon and all-done // -(void