Automatic Subversion Revision Stamping for iPhone Projects

Posted by: on May 26, 2010 in Blog | Tags: , , , , | 2 Comments

Early during development of a new iPhone OS application, I discovered that App Store submissions must use a strict format for the CFBundleVersion key in the Info.plist file. It can only be numbers and dots. This left me a little frustrated with how to version pre-1.0 releases to testers. I didn’t want to use an open-source style “0.9” and yet it wasn’t 1.0. What I really wanted was “1.0 b1” or similar.

I stumbled on Daniel Jalkut’s post about automatically stamping the Subversion revision into Info.plist and thought that might be a good way to go. I also created a new key in Info.plist, LYSApplicationDisplayVersion, that I use as a human-friendly version string, which is where I get my preferred “1.0 b1” form. CFBundleVersion now takes the form of major.minor.revision, where major and minor are the important parts of the human-friendly version (“1.0”) and revision is the Subversion revision number that produced the binary.

I like this method because it solves one problem raised by commenters on Daniel’s post. Because the Subversion revision is the third component, it doesn’t matter that r3999 is a mature 1.2 point release and r4000 is a risky pre-2.0 alpha for testers. Those versions end up 1.2.3999 and 2.0.4000 and it’s clear that they are from two different branches of development. For iPhone Ad Hoc distribution, iTunes also parses the version properly and knows that 1.0.100 is newer than 1.0.95.

Here is the script to paste into your custom script build phase:

# Xcode auto-versioning script for Subversion
# by Axel Andersson, modified by Daniel Jalkut to add
# "--revision HEAD" to the svn info line, which allows
# the latest revision to always be used.
use strict;
die "$0: Must be run from Xcode" unless $ENV{"BUILT_PRODUCTS_DIR"};
# Get the current subversion revision number and use it to set the CFBundleVersion value
my $REV = `/usr/bin/svnversion -n ./`;
my $version = $REV;
# (Match the last group of digits and optional letter M/S/P):
# ugly yet functional (barely) regex by Daniel Jalkut:
#$version =~ s/([\d]*:)(\d+[M|S]*).*/$2/;
# better yet still functional regex via Kevin "Regex Nerd" Ballard
($version =~ m/(\d+)([MSP]*)$/) && ($version = $1);
die "$0: No Subversion revision found" unless $version;
die "$0: Modified, switched or partial working copy, you sure about that?" if $2 && ($ENV{"BUILD_STYLE"} eq "Ad Hoc" || $ENV{"BUILD_STYLE"} eq "App Store");
open(FH, "plutil -convert xml1 \"$INFO\" -o - |") or die "$0: $INFO: $!";
my $info = join("", <FH>);
$info =~ s/([\t ]+<key>CFBundleVersion<\/key>\n[\t ]+<string>\d+\.\d+).*?(<\/string>)/$1.$version$2/;
open(FH, "| plutil -convert binary1 - -o \"$INFO\"") or die "$0: $INFO: $!";
print FH $info;

There are a couple of other changes to this script for Subversion 1.5 and later, and for iPhone OS targets.

The first is that the regular expression allows for a trailing P in the Subversion revision. This signals a working copy from a sparse checkout, which I never use and therefore may be a problem. I have the script fail if any letter is appended to the revision when the BUILD_STYLE is “Ad Hoc” or “App Store”, which are two new configurations, cloned from Release, that I use for Ad Hoc and App Store distribution, respectively. Especially for modified working copies: I never want to accidentally hand out a build made from a modified working copy. Should the day come that I really do, I can comment this line out, make the build, and uncomment it again.

The second is that iPhone projects convert Info.plist to the binary plist format in the application bundle. In order to extract the existing CFBundleVersion key, it must be converted back to XML. When writing the plist back out, it is again converted to binary. Both of these steps use plutil, which is part of the Developer Tools.

Ruby, Threads and RubyCocoa

Posted by: on May 24, 2010 in Blog | Tags: , | No Comments

If you’re a Rails developer working on Mac OS X 10.6, you may have seen this message:

Ruby threads cannot be used in RubyCocoa without patches to the Ruby interpreter

It is caused by a plug-in or gem requiring osx/cocoa, frequently attachment_fu. AttachmentFu can use CoreImage as an image processor instead of calling out to an image manipulation library such as ImageMagick or GD2.

The warning is harmless, but it can be very noisy. To disable it, you can simply remove CoreImage from AttachmentFu’s list of image processors by creating a new file in config/initializers. Its contents should be this one line:


Image resize operations will now use one of the other image processors, which you can install from MacPorts. I never deploy to a Mac OS X server for production, and I prefer to run as much of the same code as possible in development, so this isn’t a problem for me.

Tim O’Reilly on Raising VC

Posted by: on May 5, 2010 in Blog | Tags: , | No Comments

Tim O’Reilly, interviewed by Inc. in The Oracle of Silicon Valley, on raising venture capital and the potential of his company getting really big:

“Money is like gasoline during a road trip,” he says. “You don’t want to run out of gas on your trip, but you’re not doing a tour of gas stations. You have to pay attention to money, but it shouldn’t be about the money.”

Remember HTTP Password in Mobile Safari

Posted by: on May 3, 2010 in Blog | Tags: , , | 4 Comments

In iPhone OS 3.0, Apple allowed Mobile Safari to save usernames and passwords in web forms. Unfortunately, Safari does not offer to do the same thing for HTTP Basic and Digest authentication. I’ve become fond of using HTTP authentication because it is very easy to set up, either in your Apache virtual host configuration or within a Rails application. There are many times that a full-fledged user database is unnecessary for a simple administration back-end.

There is a work-around, though it does mean storing your user and password in plaintext in your device’s bookmarks. HTTP allows you to supply authentication credentials as part of the URL, in the form

Use content_for to Put Markup In Its Place

Posted by: on May 3, 2010 in Blog | Tags: , | No Comments

Here is a useful trick for ensuring that you keep your partial templates well organized without sacrificing page-load times or duplicating your layouts unnecessarily.

You can use content_for to capture some markup, but have it emitted into the page from somewhere else.

Two places this is immediately useful: adding additional tags inside <head> and placing in-line Javascript near </body>, while keeping the code itself right next to the DOM elements it works upon.

content_for works by capturing whatever appears inside the block and storing it for later use. You emit whatever is stored using yield. What’s more, content_for doesn’t clobber the previous captured text if you use it more than once with the same key.

Say you have a fancy Javascript control that replaces a standard <select> element in forms. You can do this in your partials:

<select ...>
<% content_for :body_close do %>
  <script type="text/javascript">
    // code that does something with that <select>
<% end >

And then in your layout, just before the </body>:

<%= yield :body_close %>

Because most browsers will run in-line Javascript upon encountering it, this would delay the execution of the code until all of the page content was loaded, making your page appear to load faster.

What’s more, if that fancy Javascript control also requires a CSS file, but you don’t want to require the browser to fetch it on all of the other pages that don’t need it, you can conditionally add it to <head> by defining another content_for key that accumulates additional markup to go there:

<% content_for :head do %>
  <%= stylesheet_link_tag 'fancy_control' %>
<% end %>

And in your layout:

  <%= yield :head %>

This is also useful for keeping per-page markup like <title> and meta tags in the template and out of your controller.