Swift: tab bar missing when presenting a view controller - how to solve this?

问题

I have created a simple tab bar with three views in storyboard. The tab bar works well, but when I try to show another view controller from a button within a tab, the new view is placed over the whole screen and also over the tab bar.

This is how I present the view so far when a button is pressed:

@IBAction func buttonPressed(_ sender: UIButton) {

        let newVC = self.storyboard?.instantiateViewController(withIdentifier: "extraVC")
        self.present(newVC!, animated: true, completion: nil)
    }

The other idea I had was this:

        self.tabBarController?.present(vc!, animated: true, completion: nil)

But not to my surprise this didn't work either.

So how can I present another view controller within the tab bar (so that the bottom bar is still shown)?

回答1:

When you present a view controller modally, its presentation style will be "Full Screen" by default. What you want to do is have it do in this case is just cover part of the screen (the part where the presenting view controller is drawn.

One way to accomplish this is to:

Set the modalPresentationStyle for the presented view controller to be .currentContext or .overCurrentContext
In the view controller that will be presenting the modal, set its definesContext property to true.

These steps can be done either in Interface Builder by setting attributes on the segue and the view controller, or you can modify your code to include the following:

@IBAction func buttonPressed(_ sender: UIButton) {
    let newVC = self.storyboard?.instantiateViewController(withIdentifier: "extraVC")
    self.definesPresentationContext = true
    newVC?.modalPresentationStyle = .overCurrentContext
    self.present(newVC!, animated: true, completion: nil)
}

What this combination of properties does is:

Indicate for the presented view controller that you want it to be presented in a non-full screen context (some specific section of the screen)
Indicate that the presenting view controller is is the section of the screen / the context you want the modal to be drawn according to.

More details can be found in the Apple Documentation

回答2:

When you are using present method, the ViewController is presented modally and covers your UITabBarConntroller. Instead of showing your view modally you can embed every first view controller in your TabBar into UINavigationController and then use method pushViewController to push it onto stack. You will have your TabBar visible and nice looking animation for free.

回答3:

In Xcode, I created a new project using the Tabbed App template to illustrate the solution above. This will create a project with a tabbar controller and two view controllers. I added a button with the title "view page" to the first view controller and embedded a navigation controller from the storyboard.

The storyboard will look like this after making the above changes:

In the FirstViewController.swift file, I created an IBAction for the button with the following code that will create another view controller called DetailViewController, with the title Favorites and a background color of orange. I used the navigation controller to present it by pushing it onto the navigation controller stack.

@IBAction func viewPageButtonTapped(_ sender: UIButton) {
    print("viewPageButtonTapped")
            let pinkViewController = DetailViewController()
    pinkViewController.title = "Favorites"
    pinkViewController.view.backgroundColor = UIColor.orange
    navigationController?.pushViewController(pinkViewController, animated: true)
}

When I run the project on the simulator, I got the desired result. Hope this helps give you some ideas.

回答4:

You should present a view controller in a primary context instead of present it modally. For that, instead of:

@IBAction func buttonPressed(_ sender: UIButton) {
    let newVC = self.storyboard?.instantiateViewController(withIdentifier: "extraVC")
    self.present(newVC!, animated: true, completion: nil)
}

call to show:

@IBAction func buttonPressed(_ sender: UIButton) {
    let newVC = self.storyboard?.instantiateViewController(withIdentifier: "extraVC")
    self.show(newVC!, sender: self)
}

回答5:

In your viewController do:

self.tabBarController?.present(nextViewController, animated: true/false, completion: {})

来源：https://stackoverflow.com/questions/46939931/swift-tab-bar-missing-when-presenting-a-view-controller-how-to-solve-this

标签

ios

swift

viewcontroller

tabbar