Can i do the initialization in a method?

Question

For example, i got a method like this:

- (void)addToRecents:(NSDictionary *)photo
{
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    NSMutableArray *recents = [[defaults objectForKey:@"RecentPhotos"] mutableCopy];
    if(!recents) recents = [NSMutableArray array];
    [recents addObject:photo];
    [defaults setObject:recents forKey:@"RecentPhotos"];
    [defaults synchronize];
    self.recentPhotos = [[NSUserDefaults standardUserDefaults] objectForKey:@"RecentPhotos"];    
    [self.tableView reloadData];
}

Then it always couldn't show the tableview i want. I use the nslog to print something in - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath to see if this method really got called. Then i found out it never got called.

Answer 1

I did the above cause from my past experience in C or Java, i think the place where you do the setup or initialization doesn't matter, as long as you just do it anywhere you want even in a method or function like these lines:

self.recentPhotos = [[NSUserDefaults standardUserDefaults] objectForKey:@"RecentPhotos"];    
[self.tableView reloadData];

However it didn't work at all. It took me about one hour to check every other stuff to figure it out cause i always thought i'm doing the right way like in Java.

Then i tried to put them inside the viewDidLoad(), it worked. I watched the Stanford lectures about viewController lifecycle again and as Paul said: it's better to do all the setup or initialization in the vieDidLoad(). Now I learn this difference.

This is just my own experience from working on the assignment 4.

Hope it would help others not waste too much time on this. Thanks

Answer 2

I spent a couple of hours on that part myself. A couple of comments that I hope would help:

1- You are really using the NSUserDefaults backward. I would continuously add the images to the local array and then just setObject that array up to the preferences (versus updating NSUserDefaults and copying it to the local array). Just more logical.

2- I don't think that the location of the reload in your code was the issue. I just tested it on my code and it worked fine. For some reason, as I was moving the VC in the IB, it disconnected the Source and delegate. So I had to reconnect them. I am wondering if that is what happened with you.

3- Tip as you progress in the assignment: once you embed the VCs in the TabBarController, think of the sequence of events for the table reload :-)

KB