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You should also check out the other blogs on the list. They’re all on my daily reading list.

Post from iPhone Development Blog Copyright © 2009 Nick Dalton - iPhone Developer

The iPhone Development Blog Named a Top 10 Blog by oDesk

1. Download and store HTML documents that are rendered using the UIWebView class.
2. Download and store the external documents referenced in the HTML, like images, so that they, along with the HTML documents, are available in non-networked situations.
3. Use the same HTML documents and external documents as the body of in-app generated Emails.

The challenge was to devise a scheme whereby the same HTML documents can be used for both rendering content within the app under non-networked situations and to provide the exact same user experience within the Email body; a clear Catch-22!

There are a number of possible approaches (see page 10 of Nick’s presentation, but the one we choose was to use complete URL’s for all externally referenced documents within the HTML (for example, all images are referenced on a CDN). We choose this route as it provides the simplest way to support the Email requirement.

Next we had to figure out a way to modify these URL’s dynamically to reference the same external documents located locally on the device. To do this we use some features of UIWebView and Javascript.

First we set up the UIWebView and implement the webViewDidFinishLoad delegate method to kick off the Javascript. Below you can see we take advantage of the webview’s stringByEvaluatingJavaScriptFromString() method to call our Javascript event listener useLocalPaths().

- (void)webViewDidFinishLoad:(UIWebView *)webView {
  DLog(@"Local URLs used = %@",[webView stringByEvaluatingJavaScriptFromString: @"window.useLocalPaths()"]);
}

The Javascript for the event listener is the following:

<script type="text/javascript">
  window.addEventListener('load',function() {
    window.useLocalPaths = function() {
      var images = document.getElementsByTagName('img');
      for (var i=0; i<images.length; i++) {
        var url = images[i].src;
        if (url.length>0) {
          var bits = url.split('/');
          images[i].src = bits[bits.length-1];
        }
      }
      return true;
    };
  },false);
</script>

In this case, this event listener queries for all image tags and modifies the src attribute by stripping all of the URL except for the image file name. For example if our image tag looked like this,

<img src="http://www.pervasentcdn.com/pervasent.jpg" class="logo" alt="Pervasent" />

it would be come this

<img src="pervasent.jpg" class="logo" alt="Pervasent" />

and thus achieves our goal.

It’s worth noting that the general approach of using UIWebView + Javascript is quite handy and obviously has many possible applications.

Post from iPhone Development Blog Copyright © 2009 Nick Dalton - iPhone Developer

UIWebView: Dynamically Modify HTML documents

Thoughts on In-App-Purchasing For Free Apps
A thorough post by Jeff Scott at 148Apps describing the good news and the bad news for both developers and consumers.

In-App purchases could fundamentally change Apple’s App Store
Seth Weintraub at ComputerWorld postulates that everything will change. The (unanswered) question is how?

In-App Purchase now available for free apps
Marco Arment was one of the first iPhone developers to comment on the change.

Apple relents: in-app purchase for free apps allows demo-to-paid
Another good developer summary by Erica Sadun at TUAW.

Free In-App Purchases Will Change…. Little?
A somewhat pessimistic look at In App Purchase by Arnold Kim.

In App Purchase and the state of iPhone piracy
Much has been written about Apple’s statement that “Using In App Purchase in your app can also help combat some of the problems of software piracy by allowing you to verify In App Purchases”. Most of it has been ill-informed speculations by non-developers. In this post Dominique Bongard goes into great depth about the challenges of using In App Purchase to combat piracy. It’s not from a developers perspective, but from someone who has been involved in anti-piracy monitoring.

Do In App Purchases count towards the Top Grossing list?
This is one of the questions I asked in my original article. The answer seems to be yes. Freeverse analyzed the rankings of three of their games on the Top Paid list vs. the Top Grossing list. And Distmo discovered that several free apps have made it onto the Top Grossing list.

iTunes Connect Updated
On October 22 Apple made an update to iTunes Connect. After this update I was finally able to add In App Purchase to free apps, and it was also possible to change the price of an existing app with In App Purchase to free.

iPhone Developer Program License Agreement Updated
When you login to iPhone Dev Center you will be prompted to accept a new iPhone Developer Program License Agreement. I have not compared the entire document against the previous version, but one thing that I noticed had changed was specifically to allow for In App Purchase in free apps.

Post from iPhone Development Blog Copyright © 2009 Nick Dalton - iPhone Developer

In App Purchase – Roundup

• Agree that the Session was Informative? 100%
• Agree that the Speaker was Authoritative? 100%
• Agree that the Session was What you Expected? 100%
• Overall rating (1-5, 5 being best) Avg : 5

Wow! I could literally not have asked for anything more. Thank you to all of you who attended my talk. If you have not checked out the presentation, it’s available here: UIWebView – The Most Versatile Class in UIKit.

While on the topic of feedback, feel free to suggest topics you would like to see covered here on the iPhone Development Blog in the future. Is there anything you would like to see more of? Less? Comments are open.

Post from iPhone Development Blog Copyright © 2009 Nick Dalton - iPhone Developer

Thanks For The Feedback

It’s great if you have a veteran iPhone developer at your side to guide you through the jungle. To make sure that you understand the Cocoa Touch principles, get a good application architecture in place from the start, etc, etc.

Luckily you can have one of the best teachers in the business by your side for two days to get you started the right way. Dan Grigsby of Mobile Orchard fame is teaching his Two Day Beginning iPhone Programming Training Class in Portland, Nov 12-13 and in Los Angeles, Nov 19-20. You don’t need any iPhone or Mac programming experience before the class, but you should have some prior development experience, e.g. being a web developer.

More information here. If you enter the coupon code “nick”, you’ll get a nice discount if you sign up during early registration. (And no, I’m not getting any kickbacks on this.)

If you’re already past the beginner level, then you should definitely subscribe to the Mobile Orchard Podcast. It has great interviews with iPhone developers and gets into wonderfully gory details about iPhone programming and other development issues.

Post from iPhone Development Blog Copyright © 2009 Nick Dalton - iPhone Developer

Are You Serious About Becoming An iPhone Developer?

Post from iPhone Development Blog Copyright © 2009 Nick Dalton - iPhone Developer

In App Purchase for Free Apps

#include <sys/param.h>
#include <sys/mount.h>

+(float)getTotalDiskSpaceInBytes {
	NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
	struct statfs tStats;
	statfs([[paths lastObject] cString], &tStats);
	float totalSpace = (float)(tStats.f_blocks * tStats.f_bsize);

    return totalSpace;
}

This approach relies on the handy Unix statfs() function that provides the required file system information. I coded it up and it worked on my 3.x devices. Fine I thought, I’m off and running. Then when testing on a 2.x device, it crashed. The problem looks to be differences in the compiler settings between the two OS versions. Rather than figure that out (I leave that as an exercise to the reader ), I continued my search and came across what I consider the “correct” solution since it uses the iPhone SDK itself, as given below.

+(float)getTotalDiskSpaceInBytes {
	float totalSpace = 0.0f;
	NSError *error = nil;
	NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
	NSDictionary *dictionary = [[NSFileManager defaultManager] attributesOfFileSystemForPath:[paths lastObject] error: &error];

	if (dictionary) {
		NSNumber *fileSystemSizeInBytes = [dictionary objectForKey: NSFileSystemSize];
		totalSpace = [fileSystemSizeInBytes floatValue];
	} else {
		DLog(@"Error Obtaining File System Info: Domain = %@, Code = %@", [error domain], [error code]);
	}

    return totalSpace;
}

As stated in the documentation, these interfaces wrapper the statfs() function, so they ultimately do the same thing, but they have been a part of the SDK since version 2.0! Testing verified my assumption and this approach works for me on my 2.x and 3.x devices and the numbers match what iTunes shows as well.

Post from iPhone Development Blog Copyright © 2009 Nick Dalton - iPhone Developer

How To Obtain Total and Available Disk Space on Your iPhone or iPod Touch

My own humble talk was titled UIWebView – The Most Versatile Class in UIKit. A topic that should be familiar to longtime readers of this blog. For the presentation I also took the time to create complete working code examples. Another favorite request around here…

Here are the links to download the presentation and the sample code.

Post from iPhone Development Blog Copyright © 2009 Nick Dalton - iPhone Developer

360|iDev iPhone Developers Conference Presentation

I still think my own App Store Rejection Reasons page is a good complement to Apple’s official documents. And I just updated the page with a few new items that I painfully encountered.

Post from iPhone Development Blog Copyright © 2009 Nick Dalton - iPhone Developer

App Store Resource Center

If you follow the instructions in the post for a 3.0 project you will get an error:

There’s already another key named “GCC_PREPROCESSOR_DEFINITIONS”. Please enter a different name.

If you scroll through all the build settings you will not find one labeled GCC_PREPROCESSOR_DEFINITIONS. This is because this setting has helpfully been relabeled “Preprocessor Macros” and is now listed under the heading GCC 4.2 – Preprocessing:

To find out how any of these new “helpful” labels are actually translated to compiler settings, click on the Research Assistant button at bottom left corner of the window (the button that looks like a pair of reading classes on top of a stack of books) and you’ll see this:

Note that I’ve only seen this change for projects that I’ve created in Xcode 3.1.3 (which by default only have a SDK 3.0 target). Projects that were created in older versions of Xcode (even if they can target SDK 3.0) still show the GCC_PREPROCESSOR_DEFINITIONS label under the heading User-Defined.

Post from iPhone Development Blog Copyright © 2009 Nick Dalton - iPhone Developer

How To Add DEBUG Flag In A 3.0 Project In Xcode