Flutter iOS端如何设置启动屏仅支持左右横屏方向？

针对你遇到的启动屏在竖屏状态下显示异常的问题，给你两个可行的解决思路：

方案一：自定义启动屏视图控制器限制方向 #

1. 在Xcode中新建一个LaunchScreenViewController类（Swift/OC均可），继承自UIViewController
2. 在类中重写方向控制方法：
   • Swift代码：

     import UIKit
     
     class LaunchScreenViewController: UIViewController {
         override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
             return .landscapeLeft.union(.landscapeRight)
         }
     
         override var preferredInterfaceOrientationForPresentation: UIInterfaceOrientation {
             return .landscapeLeft
         }
     }
     

   • OC代码：

     #import "LaunchScreenViewController.h"
     
     @implementation LaunchScreenViewController
     
     - (UIInterfaceOrientationMask)supportedInterfaceOrientations {
         return UIInterfaceOrientationMaskLandscapeLeft | UIInterfaceOrientationMaskLandscapeRight;
     }
     
     - (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation {
         return UIInterfaceOrientationLandscapeLeft;
     }
     
     @end
     

3. 打开LaunchScreen.storyboard，选中根视图控制器，在Identity Inspector里把Class改成你刚创建的LaunchScreenViewController

方案二：通过AppDelegate动态控制方向 #

1. 在AppDelegate中，先强制启动阶段仅支持横屏：
   • Swift代码：

     func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
         // 启动时强制横屏
         UIDevice.current.setValue(UIInterfaceOrientation.landscapeLeft.rawValue, forKey: "orientation")
         return true
     }
     
     // 全局方向控制，根据当前页面动态返回
     func application(_ application: UIApplication, supportedInterfaceOrientationsFor window: UIWindow?) -> UIInterfaceOrientationMask {
         // 判断当前是否需要允许竖屏，通过Flutter端的方法调用控制
         if let flutterVC = window?.rootViewController as? FlutterViewController {
             let channel = FlutterMethodChannel(name: "com.yourapp/orientation", binaryMessenger: flutterVC.binaryMessenger)
             var allowPortrait = false
             channel.setMethodCallHandler { call, result in
                 switch call.method {
                 case "allowPortrait":
                     allowPortrait = true
                     result(nil)
                 case "forbidPortrait":
                     allowPortrait = false
                     UIDevice.current.setValue(UIInterfaceOrientation.landscapeLeft.rawValue, forKey: "orientation")
                     result(nil)
                 default:
                     result(FlutterMethodNotImplemented)
                 }
             }
             return allowPortrait ? [.portrait, .landscapeLeft, .landscapeRight] : [.landscapeLeft, .landscapeRight]
         }
         return [.landscapeLeft, .landscapeRight]
     }
     

2. 在Flutter端，打开相机前通过MethodChannel通知原生允许竖屏，关闭相机后通知禁止竖屏：

   final MethodChannel _orientationChannel = MethodChannel('com.yourapp/orientation');
   
   // 打开相机前调用
   await _orientationChannel.invokeMethod('allowPortrait');
   // 关闭相机后调用
   await _orientationChannel.invokeMethod('forbidPortrait');
   

两种方案都能解决启动屏竖屏显示的问题，方案一更直接针对启动屏，方案二适合需要全局动态切换方向的场景。

内容的提问来源于stack exchange，提问作者Savvy