Empty value in NSUserDefaults - objective-c

Question

I am developing a cocoa application. I created a user default object with this code:
NSUserDefaults *standard_user_defaults = [NSUserDefaults standardUserDefaults];
if (standard_user_defaults) {
[standard_user_defaults setObject:myString forKey:key];
[standard_user_defaults synchronize];
}
And then, I am getting the value with this code:
NSUserDefaults *standard_user_defaults = [NSUserDefaults standardUserDefaults];
NSString *val = nil;
if (standard_user_defaults)
val = [standard_user_defaults objectForKey:key];
The problem is that if I run this application in my computer is working fine, and I can get the user default value, but if another person runs the application is getting an empty value. Any ideas?

Answer 1

I assume by “another person” you mean another user on your computer. The reason they cannot read what you’ve written to your user defaults is because NSUserDefaults is meant for user-specific values. To save something that your application will be able to access from both your user account and others’, you need to place it in a file stored somewhere in a shared location on the system. One way to do this would be something like this:
NSString *basePath = [NSSearchPathForDirectoriesInDomains(NSApplicationSupportDirectory, NSLocalDomainMask, YES) objectAtIndex:0];
NSString *filePath = [basePath stringByAppendingPathComponent:#"someFileName"];
// write:
NSDictionary *dataToSave = [NSDictionary dictionaryWithObjectsAndKeys:theValue, #"someKey", nil];
if(filePath && [dataToSave writeToFile:filePath atomically:YES])
{
// success!
}
// read:
NSDictionary *dataToLoad = [NSDictionary dictionaryWithContentsOfFile:filePath];
if(dataToLoad)
{
// success!
NSString *theValue = [dataToLoad objectForKey:#"someKey"];
}

Answer 2

You should try and use valueForKey rather than objectForKey. Looking at your code, there is no reason it shouldn't work for one person and not another.
The one exception would be if you are using the defaults from the settings.bundle. Values stored into settings.bundle for user defaults are not initialized until the user opens the settings page for the first time.