如何阻止旋转以仅允许 xamarin 形式的纵向模式? [英] How can I block rotation to only allow portrait mode in xamarin forms?
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问题描述
我需要在特定页面上阻止轮播,这必须同时适用于 Android 和 iOS.
I need to block rotation on a specific page and this has to work both for Android and iOS.
我尝试使用 NuGet Plugin.DeviceOrientation 并添加以下代码
I tried using NuGet Plugin.DeviceOrientation and adding the following code
protected override void OnAppearing()
{
base.OnAppearing();
if (CrossDeviceOrientation.IsSupported)
CrossDeviceOrientation.Current.LockOrientation(Plugin.DeviceOrientation.Abstractions.DeviceOrientations.Portrait);
}
protected override void OnDisappearing()
{
base.OnDisappearing();
if (CrossDeviceOrientation.IsSupported)
CrossDeviceOrientation.Current.UnlockOrientation();
}
但抛出异常:System.NullReferenceException: '未将对象引用设置为对象的实例.'
but throws exception: System.NullReferenceException: 'Object reference not set to an instance of an object.'
推荐答案
对于 Xamarin.Forms,你可以依赖服务.
For Xamarin.Forms, you could dependency service.
创建界面:
public interface IRotate
{
void ForcePortrait();
}
安卓:
[assembly: Xamarin.Forms.Dependency(typeof(RoateHandler))]
namespace RotatePage.Droid
{
class RoateHandler : IRotate
{
public void ForcePortrait()
{
((Activity)Forms.Context).RequestedOrientation = ScreenOrientation.Portrait;
}
}
}
iOS:
[assembly: Xamarin.Forms.Dependency(typeof(RoateImplementation))]
namespace RotatePage.iOS
{
class RoateImplementation : IRotate
{
public void ForcePortrait()
{
UIDevice.CurrentDevice.SetValueForKey(new NSNumber((int)UIInterfaceOrientation.Portrait), new NSString("orientation"));
}
}
}
用法:
DependencyService.Get().ForcePortrait();
DependencyService.Get().ForcePortrait();
截图:
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