nsoperation

So, I have a group of ASINetworkQueues that currently run together resulting in a race condition when it comes to DB saves. I am trying to create an NSOperationQueue that will will queue each of these "sub queues". I currently have created an NSOperation with a main method that kicks off the "sub queue" to start it's download. My problem is that each time I add a sub queue to the main queue using "addOperation" it fires that "main" method straight away so my sub queues run concurrently. I was under the impression the main method was fired one at a time. i.e. only for the operation at the top

I'm having problems to execute a https requests, if the request don't have any error i never get the message, this is a command line tool application and i have a plist to allow http requests, i always see the completion block. typealias escHandler = ( URLResponse?, Data? ) -> Void func getRequest(url : URL, _ handler : @escaping escHandler){ let session = URLSession.shared var request = URLRequest(url:url) request.cachePolicy = .reloadIgnoringLocalCacheData request.httpMethod = "GET" let task = session.dataTask(with: url ){ (data,response,error) in handler(response,data) } task.resume() }

Related to this SO question , I want to put the data loading in the background. However, I get 'library routine called out of sequence' errors. In this SO thread say that the way is using NSOperation, but looking on the samples on the web I not know how that could solve the issue. I share a single sqlite connection with the singleton pattern: @interface Db : NSObject { NSString *path; FMDatabase* theDb; BOOL isOpen; } @property (retain, nonatomic) FMDatabase *theDb; @property (retain, nonatomic) NSString *path; @property (nonatomic) BOOL isOpen; -------- static Db *currentDbSingleton = nil;

On iOS/CocoaTouch I often see code that creates a new instance of NSAutoreleasePool within a method. I recently saw one within an NSOperation. What are the ground rules for setting up a new instance of NSAutoreleasePool? Why is this preferable to simply relying on the pre-existing release pool created in main.m? Thanks, Doug You can use a new autorelease pool whenever you want, but it is not always beneficial. It is required whenever you start a new thread or objects autoreleased in that thread will be leaked. It is also common to create new autorelease pools in a method where you create and

Is it possible to pass data from an NSOperation up the dependency chain to be used by the next NSOperation? Thanks Chris Yes. The current NSOperation can access it's dependancies via the dependencies method: NSArray *myDependancies = [self dependencies]; It can then access whatever properties you wish on the previous operations and pull out any data it requires. In a recent project I found that I needed to pass data along so often that I created a subclass of NSOperation that automatically carried forward an NSDictionary of data from one operation to the next. 来源： https://stackoverflow.com