On my work, technology and related stuff....

About me

Hi, I am Priya Rajagopal- a technologist, software architect and developer. I have worked on a wide range of technologies in my career. My current passion is mobile development. The notion of a customizable and powerful computing platform in the palm of your hand (literally) is very exciting.
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What else?

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I had an awesome time presenting on Mobile Development at Girl Develop It, Ann Arbor group. There was an incredible level of interest in this topic that explained the good turnout despite the stormy weather. 


The talk covered the basics of developing native apps for the iOS, Android and Windows platforms. In addition, an overview of some of the major cross-platform tools and frameworks including Appcelerator Titanium, Cordova PhoneGap and Xamarin Mono were provided. The talk also briefly addressed the concept of Responsive Web Design as it applies to mobile website and web apps.

You can download a copy of the talk from here

Now a brief note on the evening itself : The topic of "Women in Technology" (or lack thereof) has always been an important to me and I am always looking for opportunities to help bridge the gender gap.

So it was encouraging to be speaking to an audience where women techies were in the majority (and a special shoutout to all the men who made it and showed their support to the group). Judging by the enthusiasm of the attendees, it is quite clear that women are just as curious and interested in technology as their male counterparts  I believe that a forum that allows women to learn without fear of being judged and network comfortably with fellow women techies can be vital in encouraging more women to join the rest of us. 

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I recently gave a talk on Dynamic Fonts at Cocoaheads meeting. You can download the presentation and sample code from here.

iOS7 introduced a cool feature called Dynamic Fonts. What it essentially allows you to do is to set your preferred reading text size in Settings (General or Accessibility) app of your phone and voilà, all apps that support dynamic type automatically adjust to display text content according to the preferred size setting

In this post, I’ll go over what you would need to do to support dynamic type within your apps so that yours will be one of the cool apps that reacts to the preferred text size change!

UITextKit, Text Styles and Font Descriptors

iOS7 introduced UITextKit – a powerful framework that allows you to support rich text content, layouts and without the complexities of drawing it with Core Text or having to use UIWebView.
An important component of UITextKit is TextStyles. Text Styles describe an intended use of a font .

The table below shows the list of supported text styles and the font descriptors that define them for the case when we set the preferred text size slider settings to the center.
 

Text Styles
Font Descriptor
UIFontTextStyleHeadline
(headings)
  NSCTFontUIUsageAttribute = UICTFontTextStyleHeadline;
NSFontNameAttribute = ".AppleSystemUIHeadline";
NSFontSizeAttribute = 17
UIFontTextStyleSubheadline || Read more

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Functional Testing is system level , end-to-end testing of your app from a user's perspective. Automating the process of functional testing of your app offers several benefits – it saves time and effort, it's repeatable, simplifies regression testing, enables testing with large data sets and it can be tied into your Continuous Integration process. UI Automations is an automated functional test framework from Apple. Here, user interactions are driven by test scripts are written in JavaScript and executed using the Instruments Automation tool.

While there are several other automated functional test tools available including Calabash, KIF, Frank and Fone Monkey, UI Automations has the benefit that it is very simple to use, needs minimal or no changes to your existing app and since it's from Apple, it is (fairly) well supported and maintained.

I recently gave a talk on automated functional testing of iOS apps using UI Automations. You can download the presentation from this link. There is also a sample demo application with a corresponding set of UI Automation test scripts.

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Today, I gave an introductory level technical talk about developing mobile apps for iOS platform at the American Society Of Engineers Of Indian Origin (ASEI), MI. The ASEI is "a two level (National and Local) non-profit organization of engineers and technical professionals of Indian origin". You can learn about them at http://www.aseimi.org. I was aware of the group but I had never attended any of their meetings, so  I was not sure what to expect.

Right after work, I made the 45 mile drive to the ASEI meeting. Fighting the evening rush hour traffic, I reached there on the nick of time ; I probably made the organizers quite nervous!

There was a pretty good turn out. These were people, who just like me, had driven in from work and who probably had ten other places they'd rather be on a fall evening with picture perfect weather. I had to ensure that my talk was well worth their evening.

Soon after the featured mobile app presentation, I got started. I surveyed the room and learnt that there were less than five developers in the room. The rest of the audience was a mix of people with diverse backgrounds (different industries , different roles, varying demographics, a few were not even iPhone users). 

My presentation was intended to be fairly technical , so my challenge was to make it appeal to the diverse audience. Although they were all not developers, I knew they all had one thing in common – they were very keen on learning more about iOS mobile development. I knew that was a start.

So for the next hour or so, I quickly moved through my slides. I had material for couple of hours but I tried to focus on material that would broadly appeal.  Then the questions started pouring in and they were all very relevant. People were paying attention (well- at least most of them were) and it was interesting to see different perspectives. 

I left the meeting with a greater sense of community. 

You can download my presentation from here. It is intended to be a primer to the iOS platform and developing apps for it .

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This post describes a way to scale the text content that is presented within a UIWebview of your iOS app. Often times, there is a need to zoom in or zoom out the text content presented within UIWebview container in response to user actions. 
 
•   Run a simple Javascript on the contents of the webview using the stringByEvaluatingJavaScriptFromString method in order to adjust the size of the text.

 

NSString *jsForTextSize = [[NSString alloc] initWithFormat:@"document.getElementsByTagName('body')[0].style.
webkitTextSizeAdjust= '%d%%'", updatedFontSize*100/DEFAULTWEBVIEWFONTSIZE];
[self.myWebView stringByEvaluatingJavaScriptFromString:jsForTextSize];
 
 

In the JS above, DEFAULTWEBVIEWFONTSIZE refers to the default font size of the text content presented within the web view and updatedFontSize refers to the desired font size. So for example, if DEFAULTWEBVIEWFONTSIZE is 18 and updatedFontSize is 9, then updatedFontSize*100/DEFAULTWEBVIEWFONTSIZE evaluates to 50.

 

•   Next step is to adjust the frame height of the web view so the scaled text content is visible. The simplest way to do this is to have the UIWebView as a subview of a scrollable view (UIScrollView or  its subclass ).  That way, you can adjust the web view frame height  and correspondingly, the content size of the scroll view that encompasses it. Adjusting the  web view height is a bit tricky as described below.

 

The sizeThatFits method on web view returns a size that best fits the content. The problem with this is that when you scale up, the method returns the updated size but if the web view is large enough to display the specified content, then scaling down will not update the frame size but instead, the current frame size is returned.

 

So first , reset the current frame height  of the web view to a small value like 1.
 

    CGRectadjustedFrame = self.myWebView.frame;
    adjustedFrame.size.height= 1;
    self.myWebView.frame= adjustedFrame;
   
   

Now, obtain the frame size that would best fit the content. Since the current frame size is 1, we are scaling up. Update the frame size of the web view with the new frame size.
 

   CGSizeframeSize = [self.myWebViewsizeThatFits:CGSizeZero];
    adjustedFrame.size.height= frameSize.height;
    self.myWebView.frame= adjustedFrame;
 
  

Finally, update the content size of the UIScrollView containing the web view to accommodate the scaled content.
 

    CGSizescrollViewSize = self.myScrollView.contentSize;
    scrollViewSize.height= adjustedFrame.size.height+ self.myWebView.frame.origin.y;
    self.myScrollView.contentSize= scrollViewSize;
 
 

You can download a sample project that scales the text content of web view from  here. Shown below are some screenshots of the app.

 
   
 


 

 

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As an iOS developer (or any developer for that matter), it is not uncommon (or dare I say- its “very common”) for us to defer things while coding so as to not disrupt the current coding flow. For instance, handling of a special case or updating an algorithm with a more efficient one or just a reminder to double check a certain logic . To remind ourselves, we typically include a comment like “ToDo: Handle error code -1020” in our code.

 

Now, before we realize it, we have several “ToDos” and “FixMe” scattered throughout our project and unfortunately, many of them go unattended . Note that “attending” to them may be as simple as removing the comment because we have in fact handled the “To Do” but have just forgotten to remove the now obsolete comment which leads to clutter and confusing code.

 
 

So here is a neat little perl script that I found (and tweaked a wee bit for my purpose) that solves the problem. The script is executed  every time my project is built. The purpose of script is simple. The script greps for keywords in all the .h and .m files in the  ${SRCROOT} folder and prefixes it with a “warning”  label.

KEYWORDS="TODO|ToDo|TODO:|FIXME:|\?\?\?:|\!\!\!:" find "${SRCROOT}" \( -name "*.h" -or -name
 "*.m" \) -print0 | xargs -0 egrep --with-filename --line-number --only-matching "($KEYWORDS).
*\$" | perl -p -e "s/($KEYWORDS)/ warning: \$1/"

 

Now, every time, I compile my project, the script runs and displays all statements that begin with keywords listed in the KEYWORDS reg expression show up as warnings. They are now hard to miss and I can ensure that all the “To Do”s are handled in a timely manner.

To add the script, select “Add Build Phase” under the “Build Phases” tab of Xcode project settings.

 

Then , cut and paste the script to the “Run Script” section


Now, when you build your app, you should see all comments that include the keywords mentioned in the script listed as warnings.

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The Problem…

If you have been using Xcode  (the latest version as of writing this post is Xcode 4.6.2 ) for an extended period of time, testing your app on the iOS simulator, you may eventually encounter a “Resource temporarily Unavailable” build error . There are no build errors associated with your source code but the system is unable to successfully build your app and launch the simulator to run it . You would observe something like this in your build output.

 

 

So what’s going on?

The reason this occurs is because every time you launch the iOS simulator through Xcode to run your app and then quit /stop running the app, Xcode leaves behind a Zombie process.  If you are not familiar with Zombie processes in Unix, essentially, it is a process that has completed execution but whose entry remains in the process table. It is the responsibility of the parent process to eventually clear these processes. The zombies don’t use any of the computer resources so you won’t observe a depletion of resources , but the problem is that in this “undead” state, they hold on the PID or Process Identifier. The implication of this is that eventually, your system will run out of PIDs to assign to new processes, thereby resulting in a failure to spawn or launch a new process.

You can confirm this behavior by running your iOS app through Xcode a few times and then running the “ps” command on the terminal window. You will observe a bunch of zombie processes listed for your app. The “Z” in the “S” (or “STAT” ) column indicates that “symbolic state” of the process is a “Zombie“.

Priya-Mac-01:$ ps -aelf

UID PID PPID F CPU PRI NI SZ RSS WCHAN S ADDR TTY TIME CMD STIME

…….

 501 928 233 6000 0 0 0 0 0 - Z 0 ?? 0:00.00 (MyApp) Fri11AM

 501 1072 233 6000 0 0 0 0 0 - Z 0 ?? 0:00.00 (MyApp) Fri11AM

 501 9473 233 6000 0 0 0 0 0 - Z 0 ?? 0:00.00 (MyApp) Fri05PM

 501 11380 233 6000 0 0 0 0 0 - Z 0 ?? 0:00.00 (MyApp) Mon09AM

 501 11599 233 6000 0 0 0 0 0 - Z 0 ?? 0:00.00 (MyApp) Mon09AM

 501 11614 233 6000 0 0 0 0 0 - Z 0 ?? 0:00.00 (MyApp) 19Jun13

 501 11758 233 6000 0 0 0 0 0 - Z 0 ?? 0:00.00 (MyApp) 19Jun13

 501 12412 233 6000 0 0 0 0 0 - Z 0 ?? 0:00.00 (MyApp) 19Jun13

 501 12564 233 6000 0 0 0 0 0 - Z 0 ?? 0:00.00 (MyApp) 19Jun13

 501 13245 233 6000 0 0 0 0 0 - Z 0 ?? 0:00.00 (MyApp) 19Jun13

 501 13407 233 6000 0 0 0 0 0 - Z 0 ?? 0:00.00 (MyApp) Mon11AM

 501 13590 233 6000 0 0 0 0 0 - Z 0 ?? 0:00.00 (MyApp) 19Jun13

 501 13725 233 6000 0 0 0 0 0 - Z 0 ?? 0:00.00 (MyApp) 19Jun13

 501 14545 233 6000 0 0 0 0 0 - Z 0 ?? 0:00.00 (MyApp) Mon12PM

 501 14646 233 6000 0 0 0 0 0 - Z 0 ?? 0:00.00 (MyApp) Mon12PM

 501 14761 233 6000 0 0 0 0 0 - Z 0 ?? 0:00.00 (MyApp) Mon12PM

 501 14835 233 6000 0 0 0 0 0 - Z 0 ?? 0:00.00 (MyApp) Mon12PM

-------- 

Priya-Mac-01:$ ps -aelf | grep "MyApp"|wc -l

272

In my case, there were 272 zombie processes associated with my app that Xcode didn’t reclaim. So in case of the Xcode, you will eventually notice that you are no longer able to build the app and launch the simulator to run it. In fact, you probably won’t be able to launch  any new application. Yep- not a good place to be.

So what are your options?

Reboot:

The simplest and safest method is to reboot your system. This will get rid of the zombie processes

Re-initializing/Killing the Parent Process:

Generally , killing the  parent process corresponding to the Zombie processes should take care of it but unfortunately, in the case of Xcode, the parent process is the system launchd process. The launchd is a core system process that handles the launching of many of the other processes.  Issuing a “kill” command to the launchd process can result in undesirable results and can even make your system unresponsive. So DO NOT kill the launchd process. You could try to re-initialize the process using the kill with HUP (“Hang Up”) option but you are probably better off rebooting your Mac.

If you are curious, you can follow the steps below to determine the parent process of the Zombie Xcode process

1) You can identify the PID  (“ppid”) of the parent process corresponding to the zombie process using the command

Priya-Mac-01:$ps -p <PID of MyApp Zombie Process> -O ppid

This will output the ppid of the parent process corresponding to the Zombie process,

2) You can get details of the parent process using the following command

Priya-Mac-01:ps -p <PID of Parent Process>

PID TTY           TIME CMD

  236 ??         0:00.75 /sbin/launchd

The output of the above command indicates that the launchd process is parent process.

You can find more details on Zombie processes at you can check out  the details in http://en.wikipedia.org/wiki/Zombie_process.

 

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This post describes how to invoke a SOAP based web service from your iOS app. The post is not going to dwell into the discussion of SOAP based versus a RESTful service and neither is it intended to be a tutorial on SOAP. For more information on the latter,there are plenty of online resources including the W3C (http://www.w3.org/TR/soap/). This post assumes that your needs require invocation of SOAP based web services from your iOS app.

We will use a free online web service http://www.webservicex.net/CurrencyConvertor.asmx?WSDL for our example. This is a very simple web service handles currency conversions (surprise!).

I recommend a free utility called "wsdl2objc" which generates client-side Objective-C code from a SOAP Web Services Definition File (WSDL) file. You can always construct the SOAP request messages and parse the SOAP responses on your own without the tool, however, the tool does a lot of the heavy lifting and is convenient.

1. Download the wsdl2objc tool from http://code.google.com/p/wsdl2objc/

2. Run the wsdl2objc tool . Enter the source URL for the WSDL and the destination folder for the generated ObjC files and select "Parse WSDL" button. A screenshot of the same is shown below

3. Once the "Parse WSDL" process completes, you should see a number of ObjC files in the destination folder.

4. Follow the following steps to integrate the ObjC files into your app.
4a) Copy the ObjC files that were generated in the previous step to your app project. Make sure you select the "Copy Files Into Destination Folder" option.
Description: Macintosh HD 2 Mountain Lion:Users:mactester:Downloads:post:screenshot-copyfiles.png

4b) If you are using ARC in your project, you will have to disable ARC for the generated ObjC files. To do this, go to the "Compile Sources" section of "Build Phases" of your project and specify the "-fno-objc-arc" compiler flag for all the generated files.
Description: Macintosh HD 2 Mountain Lion:Users:mactester:Downloads:post:screenshot-disableARC.png

4c) If you already have libxml2 installed on your system (look for libxml2.dylib in /usr/lib folder), then skip this step. Otherwise, follow the steps in (4c) to install libxml2 library
4c-1)  Install the macports package installer from http://www.macports.org/install.php (if you don't have it already)
4c-2) Install libxml2 library by executing the following command in a terminal window
        sudo port install libxml2

(*Tip* For the build to work for libxml2, make sure you have the command line tools installed for Xcode )

4d) In the target "Build settings", include "-lxml2" in the "Other Linker Flags"  property
Description: Macintosh HD 2 Mountain Lion:Users:mactester:Downloads:post:screenshot-linkerflags.png

4e) In the target "Build settings", include "/usr/include/libxml2" in the "Header Search Paths"  property

Description: Macintosh HD 2 Mountain Lion:Users:mactester:Downloads:post:screenshot-headerfiles.png

4f) Import "CurrencyConvertorSvc.h" file into your implementation file and use the methods provided by this interface to make the appropriate web services calls.

The following code snippet demonstrate its usage


-(void)processRequest

{

    CurrencyConvertorSoapBinding* binding = [CurrencyConvertorSvcCurrencyConvertorSoapBinding];

    CurrencyConvertorSoapBindingResponse* response;

    CurrencyConvertorSvc_ConversionRate* request = [[CurrencyConvertorSvc_ConversionRatealloc]init];

    request.FromCurrencyCurrencyConvertorSvc_Currency_enumFromString(self.fromCurrencyTextField.text);

    request.ToCurrency = CurrencyConvertorSvc_Currency_enumFromString(self.toCurrencyTextField.text );

    response = [binding ConversionRateUsingParameters:request];

 

    dispatch_async(dispatch_get_main_queue(), ^{

        [self processResponse:response];

    });

}

 

 


-(void) processResponse: (CurrencyConvertorSoapBindingResponse*)soapResponse

{

    NSArray *responseBodyParts = soapResponse.bodyParts;

    id bodyPart;

    [self.activitystopAnimating];

    [self.activityremoveFromSuperview];

    @try{

        bodyPart = [responseBodyParts objectAtIndex:0]; // Assuming just 1 part in response which is fine

 

    }

    @catch (NSException* exception)

    {

        UIAlertView* alert = [[UIAlertViewalloc]initWithTitle:@"Server Error"message:@"Error while trying to process request"delegate:selfcancelButtonTitle:@"OK"otherButtonTitles: nil];

        [alert show];

        return;

    }

 

    if ([bodyPart isKindOfClass:[SOAPFault class]]) {

 

        NSString* errorMesg = ((SOAPFault *)bodyPart).simpleFaultString;

        UIAlertView* alert = [[UIAlertViewalloc]initWithTitle:@"Server Error"message:errorMesg delegate:selfcancelButtonTitle:@"OK"otherButtonTitles: nil];

        [alert show];

    }

    elseif([bodyPart isKindOfClass:[CurrencyConvertorSvc_ConversionRateResponseclass]]) {

        CurrencyConvertorSvc_ConversionRateResponse* rateResponse = bodyPart;

        UIAlertView* alert = [[UIAlertViewalloc]initWithTitle:@"Success!"message:[NSStringstringWithFormat:@"Currency Conversion Rate is %@",rateResponse.ConversionRateResult] delegate:selfcancelButtonTitle:@"OK"otherButtonTitles: nil];

        [alert show];

 

    }

 

}

 

An example project can be downloaded from the following link-  SOAP Test. The project has been built using Xcode 4.5.

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If you have an iPhone app or are developing one, with the launch of iPhone5 , you  need to ensure that your images scale to support the new taller retina display (640X1136).

In case of the launch image, naming the new launch with the suffix "-568h@2x" (e.g.. Default-568h@2x) will ensure that the system picks up the right launch image for the iPhone5.

However, just adding the "-568h@2x" to the new images is not sufficient to have the system pick the right images for the tall retina display. Here is a very simple category on UIImage that can be used to return the right image. Note that in the category implementation, I assume that all the iPhone5 specific images are named with a suffix of "-568h@2x".

 

The "UIImage+iPhone5extension.h" Interface definition

#import <UIKit/UIKit.h>

@interface UIImage (iPhone5extension)

+ (UIImage*)imageNamedForDevice:(NSString*)name;

@end

 

 

 

The "UIImage+iPhone5extension.m" file implementation

#import "UIImage+iPhone5extension.h"

@implementation UIImage (iPhone5extension)

+ (UIImage*)imageNamedForDevice:(NSString*)name {

 UIImage *returnImage = [UIImage imageNamed:[NSString stringWithFormat:@"%@", name]];
if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone)
 {
if (([UIScreenmainScreen].bounds.size.height * [UIScreenmainScreen].scale) >=1136)
 {
 return [UIImage imageNamed:[NSString stringWithFormat:@"%@-568h@2x", name]];
 }
 }

 return returnImage;
}

@end

 

 

Just include the above files in your project and replace relevant occurrences of [UIImage imageNamed:] call with [UIImage imageNamedForDevice:]. This would ensure that right image is picked up for non-retina,retina and tall retina versions of the resolution.

 

Mobile Video Streaming

Feb 07, 2012

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Consumption of mobile streaming video is on an upward trend. Supporting video streaming on mobile platforms presents a lot of challenges, primarily due to the diversity of devices. The decisions include encodings , file formats, streaming protocol etc. Content Distribution Networks (CDNs) and video delivery platforms exist today to alleviate the process so you don't have to worry about the video delivery aspect and can focus on the mobile app that consumes the video.
However, in order to make an informed choice about the CDNs and their offerings and the video delivery platforms, a background on mobile streaming technologies is imperative.
I recently gave a presentation at the local Mobile Monday meeting that provides an overview of mobile streaming technologies, mobile platform specific requirements and the challenges. Click Here to download the presentation.