这里有一个简单的解决方案，无需编写任何代码。

在故事板中选择视图控制器 选择属性检查器 按照下图将显示“自动”设置为“全屏”

这一变化使iPad应用程序的行为符合预期，否则新屏幕将以弹出窗口的形式显示在屏幕中央。

另一种方法是在你的应用程序中拥有你自己的基本视图控制器组件，并通过一个基本的设置来实现指定的和必需的初始化器，如下所示:

class MyBaseViewController: UIViewController {

//MARK: Initialisers

/// Alternative initializer which allows you to set the modal presentation syle
/// - Parameter modalStyle: the presentation style to be used
init(with modalStyle:UIModalPresentationStyle) {
    super.init(nibName: nil, bundle: nil)
    self.setup(modalStyle: modalStyle)
}

override init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: Bundle?) {
    super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)
    // default modal presentation style as fullscreen
    self.setup(modalStyle: .fullScreen)
}

required init?(coder: NSCoder) {
    super.init(coder: coder)
    // default modal presentation style as fullscreen
    self.setup(modalStyle: .fullScreen)
}

//MARK: Private

/// Setup the view
///
/// - Parameter modalStyle: indicates which modal presentation style to be used
/// - Parameter modalPresentation: default true, it prevent modally presented view to be dismissible with the default swipe gesture
private func setup(modalStyle:UIModalPresentationStyle, modalPresentation:Bool = true){
    if #available(iOS 13, *) {
        self.modalPresentationStyle = modalStyle
        self.isModalInPresentation = modalPresentation
    }
}

注意:如果你的视图控制器包含在一个以模态方式呈现的导航控制器中，那么导航控制器应该以同样的方式处理这个问题(也就是说，用同样的方式定制你的自定义导航控制器组件)

在Xcode 11.1、iOS 13.1和iOS 12.4上测试

希望能有所帮助

我在ios 13中使用了swizzling

import Foundation
import UIKit

private func _swizzling(forClass: AnyClass, originalSelector: Selector, swizzledSelector: Selector) {
    if let originalMethod = class_getInstanceMethod(forClass, originalSelector),
       let swizzledMethod = class_getInstanceMethod(forClass, swizzledSelector) {
        method_exchangeImplementations(originalMethod, swizzledMethod)
    }
}

extension UIViewController {

    static let preventPageSheetPresentation: Void = {
        if #available(iOS 13, *) {
            _swizzling(forClass: UIViewController.self,
                       originalSelector: #selector(present(_: animated: completion:)),
                       swizzledSelector: #selector(_swizzledPresent(_: animated: completion:)))
        }
    }()

    @available(iOS 13.0, *)
    @objc private func _swizzledPresent(_ viewControllerToPresent: UIViewController,
                                        animated flag: Bool,
                                        completion: (() -> Void)? = nil) {
        if viewControllerToPresent.modalPresentationStyle == .pageSheet
                   || viewControllerToPresent.modalPresentationStyle == .automatic {
            viewControllerToPresent.modalPresentationStyle = .fullScreen
        }
        _swizzledPresent(viewControllerToPresent, animated: flag, completion: completion)
    }
}

然后放这个

UIViewController.preventPageSheetPresentation

的某个地方

例如在AppDelegate中

func application(_ application: UIApplication,
                 didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]?) -> Bool {

    UIViewController.preventPageSheetPresentation
    // ...
    return true
}

我通过使用方法swizzling(Swift 4.2)实现了它:

创建UIViewController扩展，如下所示

extension UIViewController {

    @objc private func swizzled_presentstyle(_ viewControllerToPresent: UIViewController, animated: Bool, completion: (() -> Void)?) {

        if #available(iOS 13.0, *) {
            if viewControllerToPresent.modalPresentationStyle == .automatic || viewControllerToPresent.modalPresentationStyle == .pageSheet {
                viewControllerToPresent.modalPresentationStyle = .fullScreen
            }
        }

        self.swizzled_presentstyle(viewControllerToPresent, animated: animated, completion: completion)
    }

     static func setPresentationStyle_fullScreen() {

        let instance: UIViewController = UIViewController()
        let aClass: AnyClass! = object_getClass(instance)

        let originalSelector = #selector(UIViewController.present(_:animated:completion:))
        let swizzledSelector = #selector(UIViewController.swizzled_presentstyle(_:animated:completion:))

        let originalMethod = class_getInstanceMethod(aClass, originalSelector)
        let swizzledMethod = class_getInstanceMethod(aClass, swizzledSelector)
        if let originalMethod = originalMethod, let swizzledMethod = swizzledMethod {
        method_exchangeImplementations(originalMethod, swizzledMethod)
        }
    }
}

在AppDelegate中，在application:didFinishLaunchingWithOptions中:调用swizzling代码通过调用:

UIViewController.setPresentationStyle_fullScreen()

提示:如果你调用present to一个嵌入在NavigationController内部的ViewController，你必须将NavigationController设置为。fullscreen，而不是VC。

你可以像@davidbates这样做，也可以通过编程方式(像@pascalbros)这样做。

同样适用于UITabViewController

一个NavigationController的示例场景:

    //BaseNavigationController: UINavigationController {}
    let baseNavigationController = storyboard!.instantiateViewController(withIdentifier: "BaseNavigationController")
    var navigationController = UINavigationController(rootViewController: baseNavigationController)
    navigationController.modalPresentationStyle = .fullScreen
    navigationController.topViewController as? LoginViewController
    self.present(navigationViewController, animated: true, completion: nil)

快速的解决方案。上面已经有了很好的答案。我还添加了我的快速2点输入，在截图中显示。

如果你不使用导航控制器，那么从右菜单检查器将显示设置为全屏 如果你使用导航控制器，那么默认情况下它会显示全屏，你什么都不用做。