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"];
}