Question

Menu.h

@interface Menu : UITableViewController {    
    NSMutableArray *arrayCellCollectionOrder;
    NSMutableDictionary *dictCellCollection;
    NSMutableDictionary *dictCellIndividual;
}

@property (nonatomic, retain) NSMutableArray *arrayCellCollectionOrder;

@end

Menu.m

ViewDidLoad works as normal.

@synthesize arrayCellCollectionOrder;

- (void)viewDidLoad {

    // Codes to read in data from PLIST
    // This part works

    NSString *errorDesc = nil;
    NSPropertyListFormat format;
    NSString *plistPath;
    NSString *rootPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];

    plistPath = [rootPath stringByAppendingPathComponent:@"InfoTableDict.plist"];
    if (![[NSFileManager defaultManager] fileExistsAtPath:plistPath]) {
        plistPath = [[NSBundle mainBundle] pathForResource:@"InfoTableDict" ofType:@"plist"];
    }

    NSData *plistXML = [[NSFileManager defaultManager] contentsAtPath:plistPath];
    NSDictionary *temp = (NSDictionary *)[NSPropertyListSerialization
                                        propertyListFromData:plistXML
                                        mutabilityOption:NSPropertyListMutableContainersAndLeaves
                                        format:&format
                                        errorDescription:&errorDesc];

    if (!temp) {
        NSLog(@"Error reading plist: %@, format: %d", errorDesc, format);
    }

    arrayCellCollectionOrder = [[[NSMutableArray alloc] init] retain];
    arrayCellCollectionOrder = [temp objectForKey:@"CellCollectionOrder"]; 

    // I can access `arrayCellCollectionOrder` here, it's working.

}

cellForRowAtIndexPath works as normal. I can access arrayCellCollectionOrder.

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    static NSString *CellIdentifier = @"PhotoCell";
    PhotoCell *cell = (PhotoCell *) [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    if (cell == nil) {
        NSArray *topLevelObjects = [[NSBundle mainBundle] loadNibNamed:@"PhotoCell" owner:self options:nil];
        for (id currentObject in topLevelObjects) {
            if ([currentObject isKindOfClass:[PhotoCell class]]) {
                cell = (PhotoCell *) currentObject;
                break;
            }
        }
    }

    // Copy the specific dictionary from CellCollection to Cell Individual
    dictCellIndividual = [dictCellCollection objectForKey:[NSString stringWithFormat:@"%@", [arrayCellCollectionOrder objectAtIndex:indexPath.row]]];

    cell.photoCellTitle.text = [dictCellIndividual objectForKey:@"Title"];     // Load cell title
    cell.photoCellImage.image = [UIImage imageNamed:[NSString stringWithFormat:@"%@", [dictCellIndividual objectForKey:@"ThumbnailFilename"]]];        // Load cell image name

    return cell;

}

didSelectRowAtIndexPath NOT WORKING. I cannot access arrayCellCollectionOrder.

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {

// Browser
NSMutableArray *arrayPhotos = [[NSMutableArray alloc] init];

    NSLog(@"indexPath.row = %d", indexPath.row);        // Returns the row number i touched, works.

    NSLog(@"arrayCellCollectionOrder = %@", [NSString stringWithFormat:@"%@", [arrayCellCollectionOrder objectAtIndex:indexPath.row]]);        // DOES NOT WORK.

    // Copy the specific dictionary from CellCollection to Cell Individual
    dictCellIndividual = [dictCellCollection objectForKey:[NSString stringWithFormat:@"%@", [arrayCellCollectionOrder objectAtIndex:indexPath.row]]];        // This similar line gives error too.

    ...   ...
    ...   ...
    ...   ...
    ...   ...

}

Error is:
* Terminating app due to uncaught exception ‘NSRangeException’, reason: ‘-[__NSCFArray objectAtIndex:]: index (1) beyond bounds (0)’

i.e.: I clicked on row 1, but arrayCellCollectionOrder is NULL.
There should have data in arrayCellCollectionOrder as it’s declared in ViewDidLoad.

Is there something that I missed out?
Thanks a lot in advance.

Answer 1

arrayCellCollectionOrder = [[[NSMutableArray alloc] init] retain];
arrayCellCollectionOrder = [temp objectForKey:@"CellCollectionOrder"]; 

Do you see what you are doing to arrayCellCollectionOrder? You first assign it to a new NSMutableArray (and retain it needlessly), and then you immediately orphan the array and assign arrayCellCollectionOrder to another object that you are getting from the temp dictionary. In other words, that first line isn’t doing anything for you, other than create a leaked mutable array.

If the second line is correct and you are getting a valid object and that is what you want, then the problem is that I don’t see where that object is getting retained. As long as it is in the dictionary, it is probably retained, but if temp is discarded, then its members are released. If you did a

self.arrayCellCollectionOrder = [temp objectForKey:@"CellCollectionOrder"];

then the setter would retain it.