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Managed Object Context arrives empty when passed via a segue in iOS 5

I’ve just found that passing an NSManagedObjectContext object via a segue in iOS 5 doesn’t work: the property remains empty. In iOS 6 on the other hand this isn’t a problem: the context arrives just like any other property would, and as logic would dictate. Here’s code from an amended Utility Template app: – (void)prepareForSegue:(UIStoryboardSegue […]

How to find out what class an NSObject belongs to

Sometimes you find yourself having a reference to an object (say a View Controller), but you don’t know what class it belongs to. Thankfully there’s a method for this which will work with any NSObject: if ([self.navController isMemberOfClass:[UIViewController class]]) { self.previousTitle = @”Novels”; } In this example we’re testing if our self.navController is a UIViewController. […]

How to define a method that takes multiple parameters

I keep forgetting how to do this… don’t ask me why, it’s not that difficult! So here’s how we define one: – (void)methodName:(NSString *)parameterOne methodNameContinues:(NSString *)parameterTwo; Add more parameters as you please. In theory, the method name is split across these multiple descriptive parts before each parameter is defined. However in reality I find it […]

How to list the contents of an NSURL

On the iOS simulator we have the luxury of peeking inside our virtual devices with the Finder. We can do this by heading over to the Finder, holding down Option and clicking Go. This will bring up the Library, in which you can navigate to Application Support / iPhone Simulator / 7.0 / Applications / […]

How to display a UIImage from an NSURL

If you’re displaying images from the main iOS bundle, things are fairly straightforward: self.imageView.image = [UIImage imageNamed:@”Amy.png”]; But if you have an NSURL to your image then it’s not as easy. It took me some digging to find out that you have to convert the URL into NSData first, and then display the data: NSData […]

How to copy a file from the Main Bundle into the Documents Directory in iOS

You can do this either by using paths or NSURLs. Apple recommends using NSURLs, so here’s how it works. In this example we’re copying a file called “Amy.png” which exists in the app’s main bundle. // file URL in our bundle NSURL *fileFromBundle = [[NSBundle mainBundle]URLForResource:@”Amy” withExtension:@”png”]; // Destination URL NSURL *destinationURL = [[self applicationDocumentsDirectory]URLByAppendingPathComponent:@”Amy.png”]; […]

How to use Core Data with multiple Store Files

Sometimes it can be useful to split your Core Data Store File across multiple files. For example, one file could live on the local file system, while the other could live in iCloud. We can do this by telling the Xcode Model Editor to add more than one Configuration, each of which can be allocated […]

How to style the Tumblr Widget Sidebar Plugin

tumblr-logoI’ve been recently using Tumblr more to post sketches from all kinds of devices, and naturally I wanted to embed them in some of my websites’ sidebars.

I found the extremely helpful Tumblr Widget plugin by Gabriel Roth for this: install, drag in the widget add Tumblr URL. Done!

I wanted my images to be in a size that the widget didn’t offer, so I did some tweaking – perhaps it’ll help if you’re in a similar situation.

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