Eat Big Apple

有夠麻煩。

基本原理雖然跟在 iOS 上面差不多：如果想要讓每個 CALayer 都可以有高解析度顯示，我們就必須根據目前的解析度設定，設定每個 CALayer 的 contentsScale 這個 property，但是呢，在 iOS 上面，基本上 contentsScale 應該怎麼設定，大概只要參考 [UIScreen mainScreen] 即可，但是在 Mac OS X 上面，我們則是要去參考 NSWindow 的 backingScaleFactor property。

「Actually, Sheldon Has Better Design.」

If you're an iOS developer, and love the sitcom The Big Bang Theory, then you have to watch season 4 episode 12: The Bus Pants Utilization (original air date is January 6, 2011.)

In this episode, Leonard comes up with an idea for his iOS app and derails his friendship with Sheldon.

What's the App?

It's a handwriting-recognition based equation solver, or in Sheldon's way: 「The Surprisingly Helpful Equation-Linked Differential Optimized Numerator.」 The idea behind this is to use iPhone's camera to take a picture of the equation, and scan it with handwriting recognition, then run it through a symbolic evaluation engine, and bam.

Learning Cocoa

During the episode, they show several actual Objective-C code snippets and interesting design sketches on white boards, here are some of them:

They have a CRecognition object holds an UIImage instance variable, and sadly they name it _Photo (with underline as prefix), it's not the naming convention Apple suggested.

The next morning, Sheldon starts his own design, if you look closer, it's much more considered than Leonard's.

For example, since this is an utility app, Sheldon comes up with a flip view design that similar to built-in Camera/Stocks app. A full screen SPhotoView with a snapshot button in the middle, and on the other side, it's SEquationView and a UITableView at the bottom with some buttons.

In here, you can see more details. A UITableView holds the scanned equations, and supports rotation for landscape full screen detail view and portrait detail view. On the right side, Sheldon shows better understanding about UIViewController』s view hierarchy design concept.

Later, Leonard's team is doing some reference counting. Instead of accessing instance variable directly in -initWithPhoto: and -dealloc, they decide to use retain property self.photo, with class method to return a autoreleased CRecognition object, and claim there's no leaks.

What a mess, you should always use instance variable directly in -initWithPhoto: and -dealloc when creating/releasing instance object.

Here you see Leonard's app class hierarchy, mostly MFC-ish (thanks, @lukhnos.) style naming convention for the class names, almost everything starts with letter 「C」 (is for 「Class」 I think), CAppDelegate, CMainView, CCameraView, CSymbolicView, etc. They should use prescribed prefix like 「LRH,」 which means Leonard, Rajesh and Howard.

The beautiful Penny is next to Sheldon, and there's Facebook API on the white board.

In the end, Penny's shoes app project. There're many of them on the AppStore already, and the UI design for this one looks kinda lame.

And Sheldon is working on this project… (for customer from hell?)

Conclusion

I love and enjoy this episode a lot, and the TBBT crew does a great job for all these minor details, they look very convincing to me.

But, they should use Mac when doing the coding, I only saw Raj's MacBook Pro, and rest of them are using PCs. That's not right, you can't run Xcode on PC, well, unless they all use Hackintoshes…

Also, If you want to hire someone for your iOS app project, I highly recommend Sheldon Cooper.

References

The Big Bang Theory: 4x12 The Bus Pants Utilization

Apple: Introduction to Coding Guidelines for Cocoa