Databases
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    <p>You've got several problems in here, mostly related to modifying the UI on a background thread, which you must never do. For example:</p> <pre><code>dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, (unsigned long)NULL), ^(void) { UIActivityIndicatorView *indicator = [[UIActivityIndicatorView alloc]initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray]; indicator.frame = CGRectMake(140, 85, 40.0, 40.0); [indicator bringSubviewToFront:self.view]; [indicator startAnimating]; [self.view addSubview:indicator]; ... </code></pre> <p>Here you're modifying the current view's list of subviews on a background thread. That's not legal. Most UIKit methods have to run on the main thread (from a GCD point of view, this is the main queue).</p> <p>This line is also extremely dangerous inside of <code>viewWillAppear:</code> (or most anywhere):</p> <pre><code>[self performSelectorInBackground:@selector(getDataFromDatabase) withObject:nil]; </code></pre> <p>Your view could appear and disappear multiple times during <code>getDataFromDatabase</code> (side note: you should call this <code>fetchDataFromDatabase</code>. "get" has a special meaning in Cocoa). If the view appears multiple times, you can wind up with many threads running simultaneously, which is certainly not what you meant.</p> <p>You should almost never use <code>performSelectorInBackground:withObject:</code>. Use <code>NSOperationQueue</code> or dispatch queues to manage background operations.</p>
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    1. COI have just started learning, so complicated! Can you give me some code examples so i can have a play with it!
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    2. COHaven't got a clue where to start!
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    3. COI would start simpler. I don't see anything in the above code that needs a background thread. You can do a lot of iOS development without spawning threads. Your primary problem is that you've integrated a JSON network fetch into a view controller. Don't do that. Put your data fetches into a model class that just manages data (and use NSURLConnection to fetch the data asynchronously). Then the view controller will respond to changes in the model classes. See http://developer.apple.com/library/ios/#documentation/general/conceptual/DevPedia-CocoaCore/MVC.html
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Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

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