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{ Category Archives } code-level

An example of unit testing working for me

Some specific feedback I was given regarding my unit testing talk at VTM: iPhone fall conference was that the talk was short on real-world application of unit testing. That statement is definitely true, and it’s unfortunate that I didn’t meet the attendee’s expectations for the talk. I hope to address that deficiency here, by showing […]

On voices that matter

In October I’ll be in Philadelphia, PA talking at Voices That Matter: Fall iPhone Developers’ Conference. I’m looking forward to meeting some old friends and new faces, and sucking up a little more of that energy and enthusiasm that pervades all of the Apple-focussed developer events I’ve been to. In comparison with other fields of […]

On private methods

Let’s invent a hypothetical situation. You’re the software architect for an Objective-C application framework at a large company. This framework is used by many thousands of developers to create all sorts of applications for a particular platform. However, you have a problem. Developer Technical Support are reporting that some third-party developers are using a tool […]

On authorization proxy objects

Authorization Services is quite a nice way to build in discretionary access controls to a Mac application. There’s a whole chapter in Professional Cocoa Application Security (Chapter 6) dedicated to the topic, if you’re interested in how it works. The thing is, it’s quite verbose. If you’ve got a number of privileged operations (like, one […]

NSConference MINI videos available

During WWDC week I talked at NSConference MINI, a one-day conference organised by Scotty and the MDN. The videos are now available: free to attendees, or $50 for all 10 for non-attendees. My own talk was on extending the Clang static analyser, to perform your own tests on your code. I’m pleased with the amount […]

On detecting God Classes

Opinion on Twitter was divided when I suggested the following static analyser behaviour: report on any class that conforms to too many protocols. Firstly, a warning: “too many” is highly contextual. Almost all objects implement NSObject and you couldn’t do much without it, so it gets a bye. Other protocols, like NSCoding and NSCopying, are […]

Using Aspect-Oriented Programming for Security Engineering

This paper by Kotrappa Sirbi and Prakash Jayanth Kulkarni (link goes to HTML abstract, full text PDF is free) discusses implementation of an application’s security requirements in Java using Aspect-Oriented Programming (AOP). We have AOP for Objective-C (of sorts), but as hardly anyone has used it I think it’s worth taking a paragraph or two […]

On NSNull as an anti-pattern

All this talk about type-safe collections may leave you thinking: but what about NSNull? Let’s say you have an array that only accepts objects conforming to MyProtocol. You can’t add +[NSNull null] to it, because it doesn’t implement the protocol. So haven’t I just broken mutable arrays? Let’s be clear: NSNull is a nasty hack. […]

On type safety and making it harder to write buggy code

Objective-C’s duck typing system is both a blessing and a curse. A blessing, in that it’s amazingly flexible. A curse, in that such flexibility can lead to some awkward problems. Something that typically happens in dealing with data from a property list, JSON or other similar format is that you perform some operation on an […]