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。

我在启动屏幕后的初始视图中遇到了这个问题。修复我，因为我没有一个segue或逻辑定义是切换演示从自动到全屏如下所示:

设置导航控制器。modalPresentationStyle到。fullscreen已经重复了一千多次了，但让我给你们展示另一个阻止器，它会导致UIViewController / UINavigationController没有在全屏显示，即使所有的属性都设置正确。

对我来说，罪魁祸首就藏在这条线里

navigationController?.presentationController?.delegate = self

显然，当设置UIAdaptivePresentationControllerDelegate时，你需要在可选的delegate方法中指定表示样式

    public func adaptivePresentationStyle(for controller: UIPresentationController) -> UIModalPresentationStyle {
        presentationStyle
    }

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
}

最新版本为iOS 13和Swift 5.x

let vc = ViewController(nibName: "ViewController", bundle: nil)

vc。modalPresentationStyle = .fullScreen

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

下面是Objective-C的解决方案

UIStoryboard *storyBoard = [UIStoryboard storyboardWithName:@"Main" bundle:nil];
ViewController *vc = [storyBoard instantiateViewControllerWithIdentifier:@"ViewController"];

vc.modalPresentationStyle = UIModalPresentationFullScreen;

[self presentViewController:vc animated:YES completion:nil];