UISearchController doesn't work properly with a non-translucent UINavigationBar

问题

Currently I am trying to embed a UISearchController into my application. But the UISearchBar, which is a property of the UISearchController, doesn't get displayed properly, if the UINavigationBar is non-translucent. Usually after tapping the UISearchBar property, the UINavigationBar moves up to make room for the UISearchBar. You can see the result on the following screenshot:

https://www.dropbox.com/s/172k63zr2bhj84t/Normal_behaviour.png?dl=0

But if the "translucent" property of the UINavigationBar is set to "NO", the UISearchBar doesn't get displayed properly, because the background of the status bar remains transparent, as you can see on the following screenshot:

https://www.dropbox.com/s/v5cnxoj9ms6976r/Wrong_behaviour.png?dl=0

To demonstrate this weird behaviour, I have modified the sample project provided by Apple:

https://developer.apple.com/library/ios/samplecode/TableSearch_UISearchController/Introduction/Intro.html

Here you can download the modified version:

https://www.dropbox.com/s/7icfe6kap98g1e8/TableSearchwithUISearchControllerObj-CandSwift_MODIFIED.zip?dl=0

The modification is in file "APLMainTableViewController.m" line 33.

回答1:

It's clearly a bug (rdar://20942583).

My workaround is to set

self.edgesForExtendedLayout = UIRectEdgeAll;
self.extendedLayoutIncludesOpaqueBars = YES;

This allows you to keep the navigation bar opaque. The downside is that the content flows below the bar even if it can't be seen, creating some overhead.

回答2:

All I needed was:

func viewDidLoad() { 

    extendedLayoutIncludesOpaqueBars = true
}

回答3:

One workaround for this is to make the status bar translucent just before the search is going to become active, and remove the translucency when the search is about become inactive.

You can do this by registering your view controller as a delegate of UISearchController, and implementing the willPresentSearchController and willDismissSearchController methods. For example (in Swift):

Declare your view controller as a delegate of UISearchController:

 class MyViewController: UITableViewController, UISearchControllerDelegate

Don't forget to actually set it as the delegate, for instance in viewDidLoad add:

    searchController.delegate = self

And finally:

func willPresentSearchController(searchController: UISearchController) {
    navigationController?.navigationBar.translucent = true
}

func willDismissSearchController(searchController: UISearchController) {
    navigationController?.navigationBar.translucent = false
}