如何获取导航栏中栏按钮项的布局边距？

Question

I'm trying to create section headers in a collection view that look similar to section headers in a table view.

The text in a table view section header is aligned with the left bar button item. How do I get this alignment layout value in a collection view?

In a table view, this alignment value is in the layout margins property. I'm not able to find something equivalent in a collection view.

tableView.layoutMargins.left

Answer 1

A UIBarButtonItem is not a descendent of UIView. That's the problem. Whatever Apple is doing under the covers with the UINavigationBar is not publicly accessible. I think your best bet is a kind of hack.

Somewhere in your initialization code, do the following:

UITableView* temp = [[UITableView alloc] init];
UIEdgeInsets insets = temp.layoutMargins;
NSLog(@"%f", insets.left);

Then, save the UIEdgeInsets object and let the table disappear into the ether.

The NSLog in the above example prints out 8.000000. It seems like Apple is just using a standard value. Alternately, you could use that. But if you want to avoid hard-coding a standard value, then do what I suggest.

I'll admit, you're relying on the table, not the left bar button. But, I'm guessing what you want is to do whatever table views are doing. Good luck!