Software Creations – Orn Kristjansson

I figured I would try out developing on Mac Os making an iPhone app. My first experience on the Hackintosh building an application ( my first blog post from it as well ). Anyway, I downloaded the SDK got xCode going and followed some Hello world tutorial. I feel Hello world is just too simple to get a feel for the environment and Objective-C. So I decided to port my HandiCap Android sample to the iPhone, should give me enough time to play with xCode and get a feel for it.

As I started up xCode and started coding first I noticed was the keyboard shortcuts which are strange when using PC keyboard on the Mac, I run the Mac in a VM. I understand I can map that anyway I want so that shouldn’t be a problem if I decide to do some more development. As I knew this sample was going to be short I didn’t bother changing it. When using xCode it doesn’t really feel like an IDE rather a collection of different tools. I had a hard time finding out how to set controls on a view in the beginning once I got the appropriate tools open it was pretty much straight forward. One thing that I don’t really understand is when you link controls to the File owner, why does that link your controls to your code view ? why not link that to the view itself as that is where the code resides ? I guess I will figure that out later as time goes on.

So let’s take a look at the code, first you need to reference the controls in the header file that you already setup in the Interface builder. Yes you need to do that by hand, it is not taken care of by the IDE, more integration is needed on the IDE’s behalf if you ask me. Note the UITextFieldDelegate tag on the controller, this one is needed to hide the keyboard when Return is pressed along with code in the class file.

Then we start coding in the class ( .m ) file

I disabled the two result fields in code in the viewDidLoad function as it did not work to set Accessibility Enabled = false from the Interface builder, I don’t know why.
The textFieldShouldReturn function implements the functionality that goes with UITextFieldDelegate in the header file. Simply when the user is done with input in the two text fields he can hit return on the keyboard and the keyboard gets hidden again.
The calculate function is a straight port from the Android code, I only had to include tgmath.h and use the math functions from there.
The btCalculate_Clicked is where all the functionality happens, simply convert the text input from string to double then call calculate and display in the result fields. There is no error checking on the input as I was feeling lazy.
I’m using NSLog to log out to the console, if you want to create a program for production you should maybe write your own logging or use third party library to be able to control the logging level both debug and runtime.
Lastly we have dealloc function where we release the resources the code has been referencing. As pointed out by my friend Mick they are introducing automatic dellocations by the compiler called ARC ( Automatic Reference Counting ) in the near future. That should be welcomed by objective-c developers as they don’t have to keep track of and releasing resources, fewer bugs and more productivity. Some changes discussed on Stack Overflow This experience reminded me of other c / c++ coding with a twist I find the [ class function:param ] syntax strange, but I’m sure I can get used to that.


Below is the app in action and here is the code if anybody is interested HandiCap xCode project

In order to release your app in the Android market place you need to digitally sign it. The instructions are here. But in short I will show you what you need from the command line, you won’t have to read all the instructions. First off make your app .apk name something different then what your going to use in the end. As the process requires the input and output to have different file names.

Lets take a look, this example is from DOS command line

Create the signature key
C:\Temp> keytool -genkey -v -keystore c:\temp\release-key.keystore -alias MyAlias -keyalg RSA -keysize 2048 -validity 10000

Sign using the key
C:\Temp> jarsigner -verbose -keystore release-key.keystore release.MyApp.apk MyAlias

Verify that it took
C:\Temp> jarsigner -verify -verbose release.MyApp.apk

Run the align tool as recommended
C:\Temp> zipalign -v 4 release.MyApp.apk MyApp.apk

And your all done, now publish it and start watching the downloads.

I found out that I had not played with Text to speech in .net yet. So naturally I went to take a look how easy or hard it is to use TTS in C#. It turns out the hardest part is to find the download link for the TTS install. Its hard to understand how Microsoft sometimes seems to hide download links. Once you find the SAPI SDK page, you would think they would have download links, but not so. However you do not need the whole SDK just to do Text to speech. You only need the TTS download which has a much smaller footprint. But again, where is the download link… ? I found one Microsoft page that doesn’t make it clear, and another third party page that I used to download the TTS install.

And now for the code it self, it’s very straight forward. After installing TTS add reference to your project, choose the COM “Microsoft Speech Object Library” that will create interop dll for your project. Add a reference to the speech library in code and the Hello world sample is only two lines of code.

Another choice is to do the same without using the COM object, as COM is heavy. In that case add reference to System.Speech .net library and the code will look like this.

I had to fix an old plugin I made some time back, I did actually post about it here Java Authenticated POST. So why bring it up again, a good question I say. As Twitter changed their authentication sometime late last year ( Nov 2010 ? ). All programs using the old authentication stopped working. I hadn’t had / given myself time to look at the broken plugin. What the TeamCity twitter plugin does it to tweet when the TeamCity server starts and ends builds. If you follow that account you get notified on Twitter without having to open up your email box to see how your builds are doing.
I went googling about the new authentication and found a nice snippet on StackOverflow The snippet uses Twitter4J library to make the task really simple, check them out. The best part is that Twitter4J only needs Java 1.4 to run. That’s great as my TeamCity server only has Java 1.5 and not the newer 1.6, further as an added bonus their core jar is only 280k, that’s all I needed. Below is my code modified from the StackOverflow sample. It works fine if you are only posting to one account. The tokens and keys can be found on your Twitter app page. If you need to post for different users from your application then your code needs to take that into account. If you want the source of the plugin or all 3 plugins I have created, you can run over to GitHub and pick it up. I made it public domain, open source, whatever you want to call it.

Edit, the 3 plugins have now been added to the official TeamCity PlugIn page

I had a need to store some configuration data that is non XML compliant in my .net configuration file. As the configuration file is XML file I settled on storing the data in Base64 and then converting it back after it’s read from the configuration file. First we take the string and convert it to bytes then we convert the bytes to Base64 string that will be written to the configuration file. Reverse when you want to read the string from the configuration file.

And now for the code, as a UnitTest

I wanted to play short sound bites in a Android application, when playing sounds on the Media player there is a lag as the Media player needs to allocate memory, load the resource etc. If you need to play short sounds in response to button click or when shooting a gun in your game you need it to play instantly in response to what the user just did. In that respect SoundPool is the way to go, it allows preloading the soundbites and gives instant access to the sounds as needed. I created a simple convenience class for it as seen below.

Then all you need in your Activity is to initiate the player class and call playShortResource when you need a sound played. Your resources should be available in the res/raw directory.