nsoperationqueue

I'm trying to build a download manager class that packets all the async download (every op has its own thread) operation in an NSOperation subclass to add them later in an NSOperationQueue. The download manager class (a singleton) also exposes few methods to work on the queue and cancel operations that matches some requirements. Those are steps to start creating kind of a Class Cluster(Abstract Factory) that returns different kinds of NSOperation for different types of common operation (upload, download,parse, etc). The class seems to work pretty well with download operations, but if in the

I have a problem with my network activity indicator in that sometimes it will continue to be displayed when it should not be. I wrote my own manager for it and swapped it out for one that uses an NSAssert statement like this... - (void)setNetworkActivityIndicatorVisible:(BOOL)setVisible { static NSInteger NumberOfCallsToSetVisible = 0; if (setVisible) NumberOfCallsToSetVisible++; else NumberOfCallsToSetVisible--; // The assertion helps to find programmer errors in activity indicator management. // Since a negative NumberOfCallsToSetVisible is not a fatal error, // it should probably be removed

一、简介 一个NSOperation对象可以通过调用start方法来执行任务，默认是同步执行的。也可以将NSOperation添加到一个NSOperationQueue(操作队列)中去执行，而且是异步执行的。 创建一个操作队列： [java] view plain copy NSOperationQueue *queue = [[NSOperationQueue alloc] init]; 二、添加 NSOperation 到 NSOperationQueue 中 1.添加一个operation [java] view plain copy [queue addOperation:operation]; 2.添加一组operation [java] view plain copy [queue addOperations:operations waitUntilFinished:NO]; 3.添加一个block形式的operation [java] view plain copy [queue addOperationWithBlock:^() { NSLog(@ "执行一个新的操作，线程：%@" , [NSThread currentThread]); }]; NSOperation添加到queue之后,通常短时间内就会得到运行。但是如果存在依赖,或者整个queue被暂停等原因

Im doing some lengthy calculations to create chart data on a background thread i was originally use GCD, but every time a user filters the chart data by hitting a button, the chart data needs to be recalculated, if the user clicks the chart data filtering buttons very quickly (power user) then the chart loops through each drawing as each GCD dispatch async finishes I realize that I can't cancel threads with GCD so I've moved to trying to implement an OperationQueue I call cancelAllOperations() before adding a new operation to the queue The operations on the queue act funky, sometimes it seems

How can we implement dispatch_barrier_async 's equivalent behavior using NSOperationQueue or any user-defined data-structure based on NSOperationQueue ? The requirement is, whenever a barrier operation is submitted it should wait until all non-barrier operations submitted earlier finish their execution and blocks other operations submitted after that. Non-barrier operations should be able to perform concurrently. Barrier operations should execute serially. NB: Not using GCD ,as it doesn't provide(or atleast difficult) much access over the operations, like cancelling single operation, etc. Clay