Objective-C 将指针数组绑定到 C#

Question

我正在尝试在 Xamarin 中建立 Objective-C 库和 C# 之间的绑定。我要绑定的 class header 是这样的：

@interface MGLPolyline : MGLMultiPoint <MGLOverlay>

+ (instancetype)polylineWithCoordinates:(CLLocationCoordinate2D *)coords
                              count:(NSUInteger)count;

我想不通的是函数的第一个参数是什么。我试过这样绑定：

Static][Export("polylineWithCoordinates:count:")]
    [Internal]
    MGLPolyLine PolyLineWithCoordinates(IntPtr coord, int count);



public partial class MGLPolyLine
{
    public static unsafe MGLPolyLine PolyLineWithCoordinates(CLLocationCoordinate2D[] coords) 
    {
        unsafe
        {
            GCHandle handle = GCHandle.Alloc(coords);
            IntPtr pointer = (IntPtr)handle;

            MGLPolyLine line = MGLPolyLine.PolyLineWithCoordinates(pointer,2);

            handle.Free();
            return line;
        }

    }
}

上面的代码总是 returns 来自 MGLPolyLine.PolyLineWithCoordinates(pointer, 2) 调用的 null，这让我相信我没有正确传递数组。执行此绑定的正确方法是什么？

谢谢

编辑

我已经使用 Objective-Sharpie 来查看它会为我创建什么绑定，这就是我得到的：

// +(instancetype)polygonWithCoordinates:(CLLocationCoordinate2D *)coords count:(NSUInteger)count;
[Static]
[Export ("polygonWithCoordinates:count:")]
unsafe MGLPolygon PolygonWithCoordinates (CLLocationCoordinate2D* coords, nuint count);

现在的问题是我收到错误消息“btouch：未知类型的 CoreLocationCoordinate2D* 坐标 'MGLPolygon.PolygonWithCoordinates' (B1002)

Answer 1

原来我错误地使用了 GCHandle。工作解决方案是：

   //ApiDefinition.cs
    [Static][Export ("polylineWithCoordinates:count:")][Internal]
 MGLPolyline PolylineWithCoordinates (IntPtr coords, nuint count);

// Extra.cs
public partial class MGLPolyline
{
    public static unsafe MGLPolyline PolylineWithCoordinates(CLLocationCoordinate2D[] coords)
    {
        MGLPolyline line = null;

        fixed(void* arrPtr = coords)
        {

            IntPtr ptr = new IntPtr(arrPtr);
            line = MGLPolyline.PolylineWithCoordinates(ptr, 2);   
        }

        return line;
    }
}

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