Navigation Bar's content partially not visible in modal on iOS 13

问题

A storyboard based application is having issue rendering the navigation bar's content when the navigation bar is displayed in a modal screen, but only when on a physical device. The code behaves properly in iOS 12 and in all simulators both iOS 12 and iOS 13.2.2.

On the left of the screenshot is a iPhone 11 simulator running iOS 13.2.2; on the right is a Reflector projection of my iPhone Xs running iOS 13.2.2 of the same code. We can see there's a space between the tableview and the navigation bar content on the physical device, but on the simulator the tableview is flush against the navigation bar.

There are no table section view headers, tableview margins are set to safe area. Has anyone else experienced that issue and if so, how did you solve it?

Here's a snapshot of the stackview captured from the device, in which we can clearly see the area being mis-rendered is well within the margins of the UINavigationBar:

I was also able to replicate the issue on a brand new project when setting up the following view structure:

The code to run this demo project is available on GitHub at: https://github.com/ekscrypto/stackoverflow-59033294

With the differing behaviours:

We can see physical device showing a bar of red between the navigation bar's content and the tableview; but that red bar is not visible in the simulator.

edit: 2019-11-25 16:45 EDT -- As per comments below I tried to force a refresh of the layout using:

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    if #available(iOS 13.0, *) {
        DispatchQueue.main.async {
            self.navigationController?.navigationBar.setNeedsLayout()
            self.navigationController?.navigationBar.layoutIfNeeded()
        }
    }
}

With and without the dispatch async, as well as with and without the layoutIfNeeded; it did not solve this particular issue for me.

回答1:

Based on the answer at How to prevent gap between uinavigationbar and view in iOS 13?, which wasn't working for me, I solved my issue using the following code:

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    if #available(iOS 13.0, *) {
            self.navigationController?.setNavigationBarHidden(true, animated: false)
            self.navigationController?.setNavigationBarHidden(false, animated: false)
    }
}

回答2:

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(true)
    if #available(iOS 13.0, *) {
     self.navigationController?.setNavigationBarHidden(true, animated: false)
     self.navigationController?.setNavigationBarHidden(false, animated: false)
    }


}

来源：https://stackoverflow.com/questions/59033294/navigation-bars-content-partially-not-visible-in-modal-on-ios-13

标签

swift

modal-dialog

storyboard

uinavigationbar

ios13