Xamarin.Forms：如何在 Android 和 Z9E304D4E8DF1B7248ABZ809 上获取和添加滑动事件？

Question

・使用Xamarin.Forms

・在 UWP 上，它工作

・但是在 Android 和 ios 上，我不知道如何实现。

这是我的代码

/* Depends on the platform */
        switch (Device.RuntimePlatform) {
            case Device.iOS:
                /* iOS */
                // ????
                break;
            case Device.Android:
                /* Android */
                // ????
                break;
           
            case Device.UWP:
                /* UWP */
                /* SwipeGestureRecognize */
                var leftSwipeGesture = new SwipeGestureRecognizer { Direction = SwipeDirection.Left };
                leftSwipeGesture.Swiped += async (sender, e) => {
                    // dosomething;
                };
                var rightSwipeGesture = new SwipeGestureRecognizer { Direction = SwipeDirection.Right };
                rightSwipeGesture.Swiped += async (sender, e) => {
                     // dosomething;
                };
                Layout.GestureRecognizers.Add(leftSwipeGesture);
                Layout.GestureRecognizers.Add(rightSwipeGesture);
                break;

            default:
                break;
        }

/* 添加 * /

输出错误

[Mono] DllImport searching in: '__Internal' ('(null)').
[Mono] Searching for 'java_interop_jnienv_call_float_method_a'.
[Mono] Probing 'java_interop_jnienv_call_float_method_a'.
[Mono] Found as 'java_interop_jnienv_call_float_method_a'.
[ame.calenderap] Explicit concurrent copying GC freed 10027(810KB) AllocSpace objects, 0(0B) LOS objects, 89% free, 2866KB/26MB, paused 25us total 7.627ms
[Mono] GC_TAR_BRIDGE bridges 497 objects 504 opaque 5 colors 497 colors-bridged 497 colors-visible 497 xref 3 cache-hit 0 cache-semihit 0 cache-miss 0 setup 0.04ms tarjan 0.09ms scc-setup 0.06ms gather-xref 0.00ms xref-setup 0.00ms cleanup 0.05ms
[Mono] GC_BRIDGE: Complete, was running for 9.34ms
[Mono] GC_MINOR: (Nursery full) time 4.69ms, stw 5.53ms promoted 1600K major size: 2464K in use: 1803K los size: 1024K in use: 162K
**System.NullReferenceException:** 'Object reference not set to an instance of an object.'

添加

System.ObjectDisposedException: 'Cannot access a disposed object.
Object name: 'Xamarin.Forms.Platform.Android.Platform+DefaultRenderer'.'

请支持我！

谢谢！

Answer 1

滑动手势识别器是跨平台的，您可以阅读有关如何添加滑动手势识别器的文档。

这是一个例子：

在 xaml 中：

<BoxView Color="Teal" ...>
    <BoxView.GestureRecognizers>
        <SwipeGestureRecognizer Direction="Left" Swiped="OnSwiped"/>
    </BoxView.GestureRecognizers>
</BoxView>

在后面的代码中：

public MainPage()
{
    InitializeComponent();

    var boxView = new BoxView { Color = Color.Teal };
    var leftSwipeGesture = new SwipeGestureRecognizer { Direction = SwipeDirection.Left };
    leftSwipeGesture.Swiped += OnSwiped;
    boxView.GestureRecognizers.Add(leftSwipeGesture);
}

private void OnSwiped(object sender, SwipedEventArgs e)
{
    throw new NotImplementedException();
}