Advanced programming tips, tricks and hacks for Mac development in C/Objective-C and Cocoa.

There's a Garbage Collection ninja hiding in the project templates

Not all Xcode project templates are alike. Especially the Core Data Command Line Tool...

An unwanted feature jumped out and attacked me!

In yesterday's post on implementing a CSV parser, I briefly mentioned that the parser took around 0.28 seconds to parse the test data that I provided. I consider this a good time for the parser to take but my first run was not so quick.

The first timing test I ran gave a parsing time of 1.15 seconds. This was slightly shocking to me, since I had already run a "control" test — where I just used componentsSeparatedByString: to break into lines and then into fields — that took just 0.95 seconds.

Had I really spent all that time writing code that was 20% slower (albeit more functional) than a clumsy, brute force approach?

No. As it turns out, the Xcode Project Template I had used for the test project, the:

    Mac OS X→Application→Command Line Tool→Type:Core Data

project has Garbage Collection enabled by default.

The only real hint that this template is different is the objc_startCollectorThread() line in the default main() function — of course, I never saw this line because I always replace the source files in the templates with my own versions that follow my own formatting style.

Anyway, I turned Garbage Collection off and... boom 4 times faster.

I'd ask for more warning about these major — but subtle — changes to templates in the future but you know... ninjas, what can you do?