Based on what you described, it would seem that you simply want to reload the table anytime the view comes back on screen after the user has backgrounded it. To achieve this the way I think you want, you need to add the following in your init method for your tableView - it will tell your tableView to reload the cells properly whenever the app is about to enter the foreground:
[[NSNotificationCenter defaultCenter] addObserver:self.tableView selector:@selector(reloadData) name:UIApplicationWillEnterForegroundNotification object:nil];
This way, if the user comes back to the view by opening the app after going to the phone's settings, your tableView should reload and the changes (if any were made) should properly be reflected.
You can see a quick video of the result I tested here:
https://www.dropbox.com/s/pvjuiyofydnxnvd/textsize.mov
EDIT:
Like you said in a previous comment, it would seem like it's something wrong with your nib implementation. The only difference is where/how you update the label property. In the custom cell, I created a label property and a font property, and added the label to the cell in init, and in layoutSubviews I overrode the font. Here's the code:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
LabelCell *cell = [tableView dequeueReusableCellWithIdentifier:@"LabelCell"];
if (cell == nil) {
cell = [[LabelCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"LabelCell"];
}
cell.myLabel.text = _items[indexPath.row];
cell.myFont = [UIFont preferredFontForTextStyle:UIFontTextStyleHeadline];
return cell;
}
And in the cell itself:
- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier {
self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
self.myLabel = [[UILabel alloc] initWithFrame:CGRectMake(10, 0, self.contentView.frame.size.width - 20, 34)];
self.myLabel.backgroundColor = [UIColor greenColor];
[self.contentView addSubview:self.myLabel];
return self;
}
- (void)layoutSubviews {
[super layoutSubviews];
self.myLabel.font = self.myFont;
}
And here is the same result using custom cells with labels:
https://www.dropbox.com/s/ow2zkb6j9yq2c3m/labelcells.mov
Regarding "clearing the queue", the cells don't get queued up until they are juuuust about to be shown on screen, you can see this by logging a counter value right after you dequeue cell with identifier. If there are 10 cells on screen right now, it only dequeues 10 cells. This is the reason why you use the code if (!cell) {do stuff here that's common for all cells} and then you do things that are specific to each cell afterwards, and why this code works even if you were to assume that reloadData didn't "clear the queue", which I'm not convinced it wouldn't anyway after reading through the UITableView docs.