如何告知所有自动布局约束自行更新？ （例如，当用户更新其系统大小/动态类型时）？

Question

I'm adding Dynamic Type support to my app in iOS 7, and right now when the user changes their System Font Size and then quits and reopens the app, it updates it delightfully. However, when just launching back to the app I can't seem to get it to work.

I added an observer:

 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(contentSizeDidChange) name:UIContentSizeCategoryDidChangeNotification object:nil];

Which calls the following method when the user changes their size:

- (void)contentSizeDidChange {
     [self.tableView invalidateIntrinsicContentSize];
     [self.tableView reloadData];
}

But the type size in my cells doesn't change at all (though the height of the cell does). Is this because I subclassed UITableViewCell for my cells?

EDIT:

Here's what I have in my UITableViewCell subclass:

- (void)contentSizeDidChange {
    self.fullCellURLLabel.font = [UIFont preferredFontForTextStyle:UIFontTextStyleSubheadline];
    self.timeLeftLabel.font = [UIFont preferredFontForTextStyle:UIFontTextStyleSubheadline];
    self.timeLeftLabel.font = [UIFont preferredFontForTextStyle:UIFontTextStyleHeadline];
    self.fullCellPreviewLabel.font = [UIFont preferredFontForTextStyle:UIFontTextStyleSubheadline];
}

Answer 1

I'm going to guess here (since I did not do it) that you have to reset the text on each text object to the "preferred" size you want. When you use that method it returns a static UIFont - the font itself won't update "inside" the control.

So do this test with a static view and a few uitextfields - who knows how the system will change the fonts as the size increases? Try that in a demo project first, before you refine your real app.