MacRuby: How to create an app that can be configured from the outside?

Question

I have a MacRuby app that is meant to be customized and distributed by other people. The app really only has a few things that can be customized, but I would like to figure out a way to package the application so that a person could run a script, specify a few configuration options, and have it set up the application configuration so that it is ready to distribute to others.

For example, I have a string that points to a URL. I want someone to be able to change this URL without needing to open the project in XCode, and without having to re-build (or re-compile) so that someone on Windows or Linux could make this change.

Is this sort of thing possible? I'm new to MacRuby and Objective-C, so there may be an obvious solution to this that I am not aware of.

My Solution:

I used a plist file with the name AppConfig.plist that looked like this:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>homepage</key>
    <string>http://google.com</string>
</dict>
</plist>

And my App Delegate could access it like this:

config_path = NSBundle.mainBundle.pathForResource('AppConfig', ofType: 'plist')
@config = load_plist File.read(config_path)
# then access the homepage key like this: @config['homepage']

score 1 · Answer 1 · answered Jan 05 '12 at 22:21

1

Yes, use CFPreferences like every other app. Your users can then use the "defaults write" command (with arguments appropriate for your app) to customize its behavior without having to modify the app itself.

answered Jan 05 '12 at 22:21

jkh

3,246
16
13

After researching CFPreferences a bit more, it sounds like this is actually "user preferences" stored on the OS, not "developer configuration" that can be set before the app is installed, which is what I'm really trying to achieve. Am I mistaken? – Andrew Jan 07 '12 at 06:28
CFPreferences (or, I should also note, NSUserDefaults) is how you configure your application's behavior. I don't know what you mean by "set up before app is installed" since an App that isn't installed is, by definition, not configurable (what would you tie the configuration to? There's no bundle identifier!). Your app can ship with default preferences set which can then be changed, of course, and in that respect I was wrong the first time: If you want to be able to use the defaults(1) command, use NSUserDefaults, not CFPreferences. – jkh Jan 07 '12 at 22:31
P.S. If you want the application to be reconfigured by a 3rd party vendor, e.g. you see customization occurring by an intermediate party before the user gets it, you should simply stick a plist in your app bundle and read the data out of that directly. Then you can provide some procedure for the vendor to customize the plist. That may be actually what you're asking for here. – jkh Jan 07 '12 at 22:32
I think the plist approach is what I'm going for. Do you mind providing an example? – Andrew Jan 08 '12 at 19:49

score 1 · Accepted Answer · answered Mar 10 '12 at 21:43

The easiest way, as jkh said, is to use a plist. For example, you can store the needed customizations in Stuff.plist in the root of your project and access it using the following:

stuff = load_plist File.read(NSBundle.mainBundle.pathForResource('Stuff', ofType: 'plist'))

or if, for instance, Stuff.plist is in your Resources folder (where it probably should be)

stuff = load_plist File.read(NSBundle.mainBundle.pathForResource('Stuff', ofType:'plist', inDirectory:'Resources'))

stuff is now a Hash (or NSMutableDictionary) of your stuff. For example if Stuff.plist looked like this:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
  <key>my_stuff</key>
  <dict>
    <key>favorite_color</key>
    <string>green</string>
    <key>first_car</key>
    <string>Reliant K</string>
        </dict>
        <key>his_stuff</key>
        <dict>
    <key>favorite_color</key>
    <string>blue</string>
    <key>first_car</key>
    <string>240D</string>
        </dict>
  </dict>
  </plist>

You should be able to access the values in the following way:

    my_favorite_color = stuff[:my_stuff][:favorite_color]

I didn't actually test this in an application bundle, but I did test it using macirb. To play around with it yourself, you can load a plist file from macirb using the following:

stuff = load_plist File.read('/path/to/Stuff.plist')

MacRuby implements a load_plist on Kernel, but no write_plist or anything like that, however MacRuby does implement a to_plist on Object, so anything can be written to disk as a plist!

File.open('/path/to/new_plist.plist','w'){|f| f.write(['a','b','c'].to_plist)}

which gives you:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<array>
    <string>a</string>
    <string>b</string>
    <string>c</string>
</array>
</plist>

Now the user can define the customizations directly via plist and the already built app will read the values at runtime. Be careful with this, since you don't want to accidentally eval any rm *s.

MacRuby: How to create an app that can be configured from the outside?

My Solution:

2 Answers2