在 Xamarin iOS 的单页中强制横向模式？

Question

我使用依赖服务来强制 Android 和 iOS 中单个页面的横向， 这是安卓版的：

public class OrientationService : IOrientationService
    {
        public void Landscape()
        {
            ((Activity)Forms.Context).RequestedOrientation = ScreenOrientation.Landscape;
        }

        public void Portrait()
        {
            ((Activity)Forms.Context).RequestedOrientation = ScreenOrientation.Portrait;
        }
    }

它工作得很好并且根据需要：强制横向模式，即使手头的设备方向是纵向的，我也需要为 iOS 实现相同的功能，尝试了这个（也尝试了注释代码）：

public class OrientationService : IOrientationService
    {
        public void Landscape()
        {
            UIDevice.CurrentDevice.SetValueForKey(new NSNumber((int)UIInterfaceOrientation.LandscapeLeft), new NSString("orientation"));
            //((AppDelegate)UIApplication.SharedApplication.Delegate).CurrentOrientation = UIInterfaceOrientationMask.Landscape;
            //UIApplication.SharedApplication.SetStatusBarOrientation(UIInterfaceOrientation.LandscapeLeft, false);
        }

        public void Portrait()
        {
            UIDevice.CurrentDevice.SetValueForKey(new NSNumber((int)UIInterfaceOrientation.Portrait), new NSString("orientation"));
            //((AppDelegate)UIApplication.SharedApplication.Delegate).CurrentOrientation = UIInterfaceOrientationMask.Portrait;
            //UIApplication.SharedApplication.SetStatusBarOrientation(UIInterfaceOrientation.Portrait, false);
        }
    }

但这只有在设备处于横向模式时才会切换到横向，不像 Android 版本

Answer 1

你应该在 iOS 中做更多的事情

在 AppDelegate.cs 中

public bool allowRotation; 

并重写方法

public override UIInterfaceOrientationMask GetSupportedInterfaceOrientations(UIApplication application, [Transient] UIWindow forWindow)
 {
    if(allowRotation==true)
     {
        return UIInterfaceOrientationMask.Landscape;
     }

    else
     {
        return UIInterfaceOrientationMask.Portrait;
     }
 } 

在依赖服务中

public class OrientationService : IOrientationService
{
    public void Landscape()
    {
        AppDelegate appDelegate = (AppDelegate)UIApplication.SharedApplication.Delegate;
        appDelegate.allowRotation = true;

        UIDevice.CurrentDevice.SetValueForKey(new NSNumber((int)UIInterfaceOrientation.LandscapeLeft), new NSString("orientation"));
        //((AppDelegate)UIApplication.SharedApplication.Delegate).CurrentOrientation = UIInterfaceOrientationMask.Landscape;
        //UIApplication.SharedApplication.SetStatusBarOrientation(UIInterfaceOrientation.LandscapeLeft, false);
    }

    public void Portrait()
    {
        AppDelegate appDelegate = (AppDelegate)UIApplication.SharedApplication.Delegate;
        appDelegate.allowRotation = true;

        UIDevice.CurrentDevice.SetValueForKey(new NSNumber((int)UIInterfaceOrientation.Portrait), new NSString("orientation"));
        //((AppDelegate)UIApplication.SharedApplication.Delegate).CurrentOrientation = UIInterfaceOrientationMask.Portrait;
        //UIApplication.SharedApplication.SetStatusBarOrientation(UIInterfaceOrientation.Portrait, false);
    }
}