Arun Stephens

Core Data not returning a custom concrete class

Ever had a problem when you’re fetching something from an NSManagedObjectContext, and you’ve set a concrete class in your model, only to find that it is an NSManagedObject? Me too. I read this post at StackOverflow, which suggested that you have to create the subclass using Xcode, from within the modeler. OK, I thought. I’ll try that. I deleted my old .h and .m files. I went into the modeler. I created a new Managed Object class. Read more →

Temporary NSManagedObjectIDs

I’ve run into a problem where I insert a managed object into a managed object context, in a separate thread, and then return the object ID to the main thread and then retrieve the object from the main thread’s context using that ID. It didn’t always work. It is because I saved the first managed object context after I took the object ID. And the object ID was temporary because the object hadn’t been persisted. Read more →

binding not implemented for this SQLType 7: Core Data and iPhone OS 3

*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'binding not implemented for this SQLType 7' That’s not something you want to read. And it doesn’t make much sense. And there’s not a lot out there on that problem, either. I am adding Core Data to Zoopcast (the people-powered local search app). The first few releases just took data from the JSON web service, and put it into unmanaged objects. (As it turns out, I probably should have gone with Core Data from day one. Read more →

Images showing on iPhone Simulator but not device?

If you’re working on an app (Zoopcast, say) and you’re finding that images that you’ve got in your application bundle are showing up when you’re running in the simulator, but not on the device, check the case of your filenames. I thought there might have been some sort of image format problem that [UIImage imageNamed:] uses, but I was wrong. It was simple case sensitivity. I’m guessing that my computer has a case-insensitive filesystem whereas the iPhone and iPod I am testing on presumably have a case-sensitive one. Read more →

CLLocationCoordinate2DMake is new in iOS 4

I hadn’t done any Core Location work before iOS 4 came out. But now I am. And I ran into a very odd EXC_BAD_ACCESS bug when running on an iPod touch that’s running iPhone OS 3.1.3. I pinpointed the problem (actually, I think it was only a problem, because I did a lot of other refactoring to get to this point) was with CLLocationCoordinate2DMake. And I finally realised when looking in the header that it’s new for iOS 4. Read more →

To Three20 or not to Three20…

My answer, and one I wish I came to a bit earlier, is not to Three20. And the reason is this. It is a completely different architecture to the native UIKit framework. Which is fine, it’s supposed to be. But because of this, making what should be minor changes to the appearance of a table view cell, for example, can become troublesome. Some of the problems I had were because of the lack of documentation. Read more →

Fruits of the iPhone posts

An avid reader of this blog (i.e. no one) will have noticed that lately there have been quite a few posts about iPhone development. Well, I am pleased to announce (on behalf of Zemobo) that Zemobo Rugby has now launched on the iTunes App Store. It ties in with Zemobo’s Rugby Picks app on Facebook. You can download it from It’s free! Read more →

Modal view controllers and recursion causing stack overflow

Ironically, it was this post at Stack Overflow that helped me solve this problem! There appears to be a bug (either in the iPhone SDK or my understanding of it) that if you dismiss a modal view controller with animation using UINavigationController’s dismissModalViewControllerAnimated, it will cause some sort of weird recursion that causes a stack overflow (over 4000 frames were in the stack when it crashed, and it took a split second for it to fill up in the Simulator) if you then want to display the modal view controller again using presentModalViewController. Read more →

OpenID and iPhone apps

I am trying to find an OpenID implementation that is similar to the way that Facebook Connect’s login mechanism works on the iPhone. I can’t find anything, which is very surprising. Does anybody know of an open source OpenID consumer implementation for iPhone OS? And if you don’t know of one, are you looking for one? If I can’t find one, I am going to have to write my own, and it’s something that I think would do well to be open sourced, so if you are interested, please post a comment. Read more →

Width of grouped UITableViewCell

I am working on some iPhone development at the moment. I have built a cell for a UITableView in Interface Builder. The cell was a bit too wide for the cell in my table view, and I realised it was because the cell in the NIB is full width but I am loading it into a grouped table view. I didn’t want to have to measure it myself so I searched for the width. Read more →