Question

I’m encountering a weird issue where storing an NSDictionary to the NSUserDefaults and then retrieving it converts it to an NSCFString.

Here’s where I save the data:

- (void)saveProgress
{
    // Save our progress to the user defaults.
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    NSMutableDictionary *progressDict = [NSMutableDictionary dictionary];
    if ([defaults objectForKey:@"session_progress"] != nil) {
        [progressDict addEntriesFromDictionary:[defaults dictionaryForKey:@"session_progress"]];
    }
    NSMutableDictionary *targetsDict = [NSMutableDictionary dictionary];
    if ([progressDict objectForKey:@"targets"] != nil) {
        [targetsDict addEntriesFromDictionary:[progressDict objectForKey:@"targets"]];
    }
    NSMutableDictionary *trackableDict = [NSMutableDictionary dictionary];
    if ([targetsDict objectForKey:@"mda_sao_ext_04"]) {
        [trackableDict addEntriesFromDictionary:[targetsDict objectForKey:@"mda_sao_ext_04"]];
    }
    [trackableDict setObject:[NSNumber numberWithBool:YES]
                      forKey:@"viewed"];
    NSLog(@"SAVE Trackable %@ %@", [trackableDict class], trackableDict);
    [targetsDict setObject:trackableDict
                    forKey:@"mda_sao_ext_04"];
    NSLog(@"SAVE Targets %@ %@", [targetsDict class], targetsDict);
    [progressDict setObject:targetsDict
                     forKey:@"targets"];
    [defaults setObject:progressDict
                 forKey:@"session_progress"];
    [defaults synchronize];
}

And here’s where I load the data:

- (NSInteger)loadProgress
{
    // Load our progress from the user defaults.
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    if ([defaults objectForKey:@"session_progress"] == nil) {
        return 0;
    }
    NSDictionary *progressDict = [defaults dictionaryForKey:@"session_progress"];
    if ([progressDict objectForKey:@"targets"] == nil) {
        return 0;
    }
    NSDictionary *targetsDict = [progressDict objectForKey:@"targets"];
    NSLog(@"LOAD Targets %@ %@", [targetsDict class], targetsDict);
    NSInteger viewedCount = 0;
    for (NSDictionary *trackableDict in targetsDict) {
        NSLog(@"LOAD Trackable %@ %@", [trackableDict class], trackableDict);
        if ([[trackableDict objectForKey:@"viewed"] boolValue]) {
            ++viewedCount;
        }
    }

    return viewedCount;
}

The app crashes in loadProgress. Here’s the output to the console:

LOAD Targets __NSCFDictionary {
    "mda_sao_ext_04" =     {
        scanned = 1;
        viewed = 1;
    };
} 
LOAD Trackable __NSCFString mda_sao_ext_04

You can see from the first trace that `mda_sao_ext_04 is a dictionary, but for some reason it gets converted to a string.

Any ideas or suggestions? Thanks!

Answer 1

Fast enumeration of NSDictionary returns keys, not values.

for (NSDictionary *trackableDict in targetsDict) {

here you loop over all keys. Change

NSLog(@"LOAD Trackable %@ %@", [trackableDict class], trackableDict);

to

NSLog(@"LOAD Trackable %@ %@", [trackableDict class], targetsDict[trackableDict]);