Re: NSUserDefaults from within a bundle

FROM : Benjamin Einstein
DATE : Sun Jul 02 20:33:07 2006

Thanks to the both of you. These first couple weeks of Cocoa 
development have been pretty simple, but I still have a bit of 
trouble with some of the concepts (as you've noticed). Strangely 
enough, I've spent the last two hours doing exactly what you 
suggested just now; writing to the MySQL database. It seems to work 
quite well, if only a little slow. Other suggestions are eye-opening, 
but the a database-based preference system seems the most logical, 
considering it's a database-based app.

Thanks again!

On Jul 2, 2006, at 2:25 PM, Paul Collins wrote:

> On Jul 2, 2006, at 9:17 AM, Benjamin Einstein wrote:

>>  We would really prefer to have global, "traveling" preferences 
>> that are embedded in the application bundle but can be modified 
>> locally (don't worry about rights, you must be a system admin and 
>> an application admin to make preferences changes). Is there a way 
>> to use NSUserDefaults to do this? Maybe CFPreferences?...
>>
>> There's one major catch: the application would have to be copied 
>> back when the user quits so other users get their updated 
>> preferences. Hmmmm. It would be okay unless the write failed.

>
> A few concepts that may be applicable, or not...
>
> NSUserDefaults has "defaults domains" that have a precedence order: 
> the existence of a particular preference in one domain overrides 
> that pref in any lower domains (when you are getting the value of 
> the pref in your code). The "Registration" domain is lowest. It is 
> hard coded in your app (I do it in my app delegate's init method). 
> These are never changed (unless you release a new version of the 
> whole app), but are overridden by prefs in any other domain, such 
> as when the user changes a pref locally and it is stored in the 
> user's Preferences folder by NSUserDefaults.
>
> Again, what Bill said about the app bundle--think of the app bundle 
> as read-only.
>
> CFPreferences is the Core Foundation API to the *same* preferences 
> system as NSUserDefaults, but has lower-level flexibility. In 
> particular, it lets you write prefs to different places, in what 
> are called "Preference Domains" - which are completely different 
> than ("orthogonal to") NSUserDefaults "Defaults Domains"! 
> "Preference Domains" includes an "any host" concept that you might 
> like, although I am not sure what the boundaries of this are (local 
> network??).
>
> You can read up on all this in the ADC reference library in Xcode's 
> built-in documentation.
>
> In case you haven't figured this out yet:  Cocoa's NS classes are 
> always the first place to look, but for some low-level or unusual 
> functionality you may need to drop down into Core Foundation's CF 
> functions, or even go over to Carbon (for certain GUI or event 
> functions that haven't made it into Cocoa).
>
> One other thought: can you just put these shared "preferences" into 
> the SQL database?
>
> Welcome to Mac programming, and good luck!
>
> --Paul Collins
>
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