StackOverflow2013

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PONSOperation synchronization problem
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copied!<p>I am struggling to find a way to synchronize operation on IPhone app. I have three main NSOperation.</p> <pre><code> NSInvocationOperation *showSpinner = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(spinnerOn:) object:YES]; NSInvocationOperation *reloadDatasource = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(reloadDatasource) object:nil]; NSInvocationOperation *hideSpinner = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(spinnerOn:) object:NO]; // Add dependency [reloadDatasource addDependency:showSpinner]; [hideSpinner addDependency:reloadDatasource]; [self.queue addOperation:showSpinner]; [self.queue addOperation:reloadDatasource]; [self.queue addOperation:hideSpinner]; </code></pre> <p>I can see that the three operations are correctly started in sequence. However, as you can imagine, the first operation create a UIView and attach it on top, while the last one should remove it. </p> <p>It happens that graphically speaking the operations happens at once on the screen. So I can see the table already loaded, while the spinner is on screen, or other strange unsynchronized things.</p> <p>I understood that change on the graphic side happen on the main thread. So I am asking how can I modify the code to do what it is supposed to do. Which is: create spinner, load data, and remove spinner ? Is there a common way to separate graphic operation and data operation ? For example create two distinct operation. </p> <p>thanks</p>

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