Calligraphic Code | Tudor Munteanu

It’s a long time since I posted something serious here. Shame on me! Cheap excuse: I have been busy. Busy with work and busy enjoying the German air of my new home.

Another thing that kept me busy was this neat book published by Apress: “Pro Obj-C Design Patterns for iOS”, by Carlo Chung. True to the short paragraph on the cover “Use Objective-C design patterns to bring your iOS skill to the next level”, the book takes a deep dive into how various design patterns can be applied in the Cocoa Touch Framework and in Objective-C in general.

This book is in a pro series, so it’s not “iOS Development 101” or “Start using Objective-C in 24 hours”

In its 23 chapters, the book covers the most common software design deja-vu scenarios for:

• Object creation Interface adaptation
• Decoupling of objects
• Abstract collection
• Algorithm encapsulation
• Performance and object access
• State of objects

If you’re reading about design patterns for the first time, my advice is to take a few minutes, pause reading the book and think about each pattern you read. While the examples are well explained, source code and diagrams, sometimes in day-to-day software design the exact examples from the book can be missed. As long as the governing concepts and use cases are well understood, they can be a lot of help.

All too often, developers grind trough building good apps on willpower and a vigorous focus on code development, leaving them unaware of and unable to benefit from the underlying structural and functional design patterns.

If you want to take your iOS (and not only) coding skills to the next level, make your personal library a favor, get this book and thoroughly read it. Have a good read!

Setting up a public git repository on Mac OS has a few tricks and here’s a step-by-step
tutorial to the rescue. I needed to set this up for my own projects and most of the information was scattered across the web.

Let’s roll!

On the server

1. Install git. I’ve used both http://code.google.com/p/git-osx-installer/ and the one from Mac Ports. Both work fine.

2. What’s your public IP? Ah, I know: http://www.whatismyip.com/
If your server is behind a router, as in my case, you’ll need to setup port forwarding. Port 22 for SHH, to be precise.

3. SSH is installed by default on Mac OS. It’s accessible from Terminal, you can generate keys, but it doesn’t allow other computers to connect to your server. To enable this go to System Preferences -> Sharing and from the list on the left, check “Remote Login”.
We’ll come back here later, because it allows some more advanced settings.

4. Create a user that will manage the repositories. The simplest way is trough System Preferences -> Accounts. Create it as an
Administrator for now, and you can remove the Administration rights later on. It will make the installation easier. Let’s name it ‘git’ to remember it easier.

5. Generate an SSH key by typing the following in Terminal:

6. Setup pasword-less ssh. This is a very important step and you should not continue with the next steps if this doesn’t work.

For this, you need to generate an ssh key from your client machine, exactly like on the previous step.

The generated key will be a one-liner in ~/.ssh/id_rsa.pub. Copy this key to the server inside /Users/git/.ssh/authorized_keys.
Create the authorized_keys file if it doesn’t exist already. To check the setup, from your client machine run:

If it logs in w/o asking for a password, you’re the man! Otherwise, double check if the public key from the client corresponds with the one from the server.

7. gitolite enters the scene.

“Gitolite lets you use a single user on a server to host many git repositories and provide access to many developers, without having to give them real userids on or shell access to the server. The essential magic in doing this is ssh’s pubkey access and the authorized_keys file, and the inspiration was an older program called gitosis.

Gitolite can restrict who can read from (clone/fetch) or write to (push) a repository. It can also restrict who can push to what branch or tag, which is very important in a corporate environment”

Run the following commands in the command-line:

As a quick walkthrough, this downloads the gitolite repository, creates some required directories and runs some config scrips.
The path on the last line might vary, depending on how you named your user account that handles git.

The above scripts also create a test repository in /Users/git/repositories/

8. Do the victory dance, because you now have a git server on your Mac.

On the client

1. Install git, the same way you installed it on the server.

2. Navigate in Terminal to the location where you want the repository to be and grab the test repository by running:

3. Pushing your commits to the server might require some special settings. Since there are too many options, I won’t get into these details here. This is a link that might help: http://stackoverflow.com/questions/2816369/git-push-error-remote-rejected-master-master-branch-is-currently-checked-ou . Do remember to contribute with at least an upvote if you found the information useful. Be nice to Stackoverflow and it will be nice to you.

Happy remote coding!

Lua

For some time now I’ve been digging into Lua. Coming from Python, the power of a clean syntax and good documentation is impossible to ignore.

Lua is a powerful, fast, lightweight, embeddable scripting language.

Lua combines simple procedural syntax with powerful data description constructs based on associative arrays and extensible semantics. Lua is dynamically typed, runs by interpreting bytecode for a register-based virtual machine, and has automatic memory management with incremental garbage collection, making it ideal for configuration, scripting, and rapid prototyping.

It’s that exotic, super-fast scripting language that very few use, right? Partially right. It’s extensively used in the gaming industry (e.g. World of Warcraft) usually together with C++.

Lua comes with a console, which is great tool for fast experimenting of logic and syntax.

Lua + iOS

All fine and dandy, but how can this help me on iOS development? Stefan found the right answer: iPhone Wax .

Wax is a framework that lets you write native iPhone apps in Lua. It bridges Objective-C and Lua using the Objective-C runtime. With Wax, anything you can do in Objective-C is automatically available in Lua!” Corey Johnson, main guy behind Wax

As anyone with iOS development experience knows, Obj-C is very strict about classes, requiring a certain mindset to write good, maintainable and modular applications. Wax doesn’t alter this approach at all.

Memory management is another worry that goes away in Wax, because of the automatic garbage collection.

By this point, Wax looked completely different than any other write-quick-iphone-apps gimicks out there, including PhoneGap, Titanium, Rhomobile, Corona SDK. Do note that I mention “iPhone apps”, since the result of Wax is not cross platform. Well, a solid application should take advatage of the hardware platform and the only part that can be cross platform is the interface, even that within certain limits.

Cocoa with a sprinkle of Lua

Wax looked good in theory. A UITabBarController is a UITabBar, a delegate is a delegate, 3rd party libs work how they are intended to (Facebook, ASIHTTPRequest, custom written ones). Now let’s see it in practice.

Read the full article…