Question

I need to save a variable that increments every time a user hits a button within the app. I’ve been trying to do that with NSUserDefaults with no success. Here’s the code I’m using:

[[NSUserDefaults standardUserDefaults] setInteger:i++ forKey:@"AppCount"];

When I output this in the log, however, I keep getting 0.

Any help would be greatly appreciated.

Answer 1

Try adding:

[[NSUserDefaults standardUserDefaults] synchronize];

After each time you change the value of your integer.

Quoting Apple’s documentation on synchronize:

Writes any modifications to the persistent domains to disk and updates
all unmodified persistent domains to what is on disk.

http://developer.apple.com/library/ios/DOCUMENTATION/Cocoa/Reference/Foundation/Classes/NSUserDefaults_Class/Reference/Reference.html#//apple_ref/occ/instm/NSUserDefaults/synchronize

So with this modification, your final code should look like this:

[[NSUserDefaults standardUserDefaults] setInteger:i++ forKey:@"AppCount"];
[[NSUserDefaults standardUserDefaults] synchronize];

EDIT: Actually on second thought, give this a try:

I think the problem is using i++ assumes that the application will always be able to keep track of the count, and every time you re-enter the application i gets reset.

The following works, I just tested it.

if (![[NSUserDefaults standardUserDefaults] integerForKey:@"AppCount"]) {
    [[NSUserDefaults standardUserDefaults] setInteger:i forKey:@"AppCount"];
}else{
    [[NSUserDefaults standardUserDefaults] setInteger:[[NSUserDefaults standardUserDefaults] integerForKey:@"AppCount"] + 1 forKey:@"AppCount"];
}
    [[NSUserDefaults standardUserDefaults] synchronize];