I was discussing this with some friends and we began to wonder about this. Could someone gain access to URLs or other values that are contained in the actual objective-c code after they purchase your app?
Our initial feeling was no, but I wondered if anyone out there had definitive knowledge one way or the other?
I do know that .plist files are readily available.
Examples could be things like:
-URL values kept in a string
-API key and secret values
Yes, strings and information are easily extractable from compiled applications using the strings tool (see here), and it's actually even pretty easy to extract class information using class-dump-x (check here).
Just some food for thought.
Edit: one easy, albeit insecure, way of keeping your secret information hidden is obfuscating it, or cutting it up into small pieces.
The following code:
NSString *string = @"Hello, World!";
will produce "Hello, World!" using the strings tool.
Writing your code like this:
NSString *string = @"H";
string = [stringByAppendingString:@"el"];
string = [stringByAppendingString:@"lo"];
...
will show the characters typed, but not necessarily in order.
Again: easy to do, but not very secure.
What is it you're actually trying to accomplish? Be specific; there may be techniques to accomplish what you want, but they vary depending on your goals.
When you purchase an app it is saved on your hard disk as "FooBar.ipa"; that file is actually in Zip format. You can unzip it and inspect the contents, including searching for strings in the executable. Try it! Constant values in your code are not compressed, encrypted, or scrambled in any way.