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POhow to stop performing selector in background?
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copied!<p>I have some class A. In this class i have a method, which calls [<code>self performSelectorInBackground:...]</code>. And it starts downloading some info from internet.</p> <p>After i tap Home button, then enter the app again, this background method keeps working. So, if i call this method again, i have bad_access, because background method is already working and i call it twice.</p> <p>Can i stop performing selector in background of the class A? For example in my applicationDidEnterBackground? Or can i check, if selector is performing or something?</p> <p>I found couple things like</p> <pre><code>[[NSRunLoop currentRunLoop] cancelPerformSelectorsWithTarget:a]; [NSObject cancelPreviousPerformRequestsWithTarget:a selector:@selector(startDownload) object:nil]; </code></pre> <p>But they didn't work for me. So</p> <p>my objAppDelegate:</p> <pre><code>@inteface ObjAppDelegate { A *a; } @implementation ObjAppDelegate { -(void)applicationDidEnterBackground:(UIApplication *)application { //or it can be didBecomeActive.. //here. check if background task of class A is running, or just stop it ?? } } @implementation A { //some timer, or event, etc. -(void)startDownload { [self performSelectorInBackground:@selector(runBackgroundTask) withObject:nil]; } -(void)runBackgroundTask { //some network stuff.. } } </code></pre> <p>i did it like this:</p> <p><code><pre> threadForDownload = [[NSThread alloc] initWithTarget:self selector:@selector(threadMain:) object:nil]; [threadForDownload start]; [self performSelector:@selector(startDownload) onThread:threadForDownload withObject:nil waitUntilDone:NO];</p> <ul> <li><p>(void)threadMain:(id)data { NSAutoreleasePool *pool = [NSAutoreleasePool new];</p> <p>NSRunLoop *runloop = [NSRunLoop currentRunLoop]; [runloop addPort:[NSMachPort port] forMode:NSDefaultRunLoopMode];</p> <p>while (YES) { [runloop runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]]; }</p> <p>[pool release]; }</p></li> </ul> <p></code></pre></p> <p>In my startDownload method i look at activity indicator to check, whether startDownload is already running..</p> <p><code><pre> -(void)startDownload { if (![[UIApplication sharedApplication] isNetworkActivityIndicatorVisible]) // flag.. { //.... } } </code></pre></p> <p>// I make visible networkActivityIndicator every time i start downloading</p>

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