Question

I have used this code to load data from a plist.

-(void)loadOrCreateData {
    NSLog(@"Start loadOrCreateData");
    NSString *filePath = [self dataFilePath];
    if ([[NSFileManager defaultManager] fileExistsAtPath:filePath]) 
    {
        NSLog(@"File Exists.. Loading from plist File");
        NSArray *array = [[NSArray alloc] initWithContentsOfFile:filePath];
        font = [array objectAtIndex:0];
        background = (NSString *)[array objectAtIndex:1];
        animation = [array objectAtIndex:5];
        [array release];
        NSLog(@"Loading Done!");
    }
    else 
    {
        NSLog(@"File does not exist.. Creating new plist File");
        font = @"Georgia-BoldItalic";
        background = @"monalisa.jpeg";
        animation = @"103";
        [self saveData];
    }

    NSLog(@"Finish loadOrCreateData");
}

- (NSString *)dataFilePath {
   NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
   NSString *documentsDirectory = [paths objectAtIndex:0];
   return [documentsDirectory stringByAppendingPathComponent:@"data.plist"];
}

- (void)saveData {
   NSMutableArray *array = [[NSMutableArray alloc] init];
   [array addObject:font];
   [array addObject:background];
   [array addObject:animation];
   [array writeToFile:[self dataFilePath] atomically:YES];
   [array release];
}

The first time everything loads fine when there is no plist file to get data from. But on second load, the app crashes when I try to use the loaded data outside the loadOrCreate method. For some reason, the data in font, background and animation is not available when accessed outside loadOrCreate method. The variables –
font, background and animation are declared as NSStrings in the .h file and therefore should be globally available right? Can you please tell me what the reason for this is?

Answer 1

You have to retain that objects.

    font = [[array objectAtIndex:0] retain];
    background = (NSString *)[[array objectAtIndex:1] retain];
    animation = [[array objectAtIndex:5] retain];
...
    font = [@"Georgia-BoldItalic" retain];
    background = [@"monalisa.jpeg" retain];
    animation = [@"103" retain];

Note: if you’re loading data several times, then don’t forget to release values before you set them.

Edit:

-(void)loadOrCreateData {
    [font release];
    [background release];
    [animation release];

    NSLog(@"Start loadOrCreateData");
    NSString *filePath = [self dataFilePath];
    if ([[NSFileManager defaultManager] fileExistsAtPath:filePath]) 
    {
        NSLog(@"File Exists.. Loading from plist File");
        NSArray *array = [[NSArray alloc] initWithContentsOfFile:filePath];
        font = [[array objectAtIndex:0] retain];
        background = (NSString *)[[array objectAtIndex:1] retain];
        animation = [[array objectAtIndex:5] retain];
        [array release];
        NSLog(@"Loading Done!");
    }
    else 
    {
        NSLog(@"File does not exist.. Creating new plist File");
        font = [@"Georgia-BoldItalic" retain];
        background = [@"monalisa.jpeg" retain];
        animation = [@"103" retain];
        [self saveData];
    }

    NSLog(@"Finish loadOrCreateData");
}