ios - 使用 Mapkit 实现多个覆盖

Question

我正在做一个利用 Mapkit 框架的项目。最初有一张佛罗里达州 map ，上面有许多注释和圆形覆盖图，显示哪些区域接收送货。我想要所有这些，以及一个 MKPolygon 来突出显示整个状态。 (这是通过使用所有坐标的 XML 文件和 Objective-C 中的 XMLParser 来完成的)

MKCircleView 覆盖所有显示效果很好，我猜这是因为它们都是同一类型。但是，当我尝试实现 MKPolygon View 时，它不允许我这样做。

//Region for fort lauderdale delivery area overlay

MKCoordinateRegion fortLauderdale;
fortLauderdale.center.latitude = FTL_LATITUDE;
fortLauderdale.center.longitude = FTL_LONGITUDE;
fortLauderdale.span.latitudeDelta = SPAN_VALUE;
fortLauderdale.span.longitudeDelta = SPAN_VALUE;

//Create a circle for fort lauderdale area
MKCircle *fortLauderdaleCircle= [MKCircle circleWithCenterCoordinate:fortLauderdale.center radius:5000];
//2KM or 1.24 miles
[self.mapView addOverlay:fortLauderdaleCircle];

//Region for miami delivery area overlay

MKCoordinateRegion miami;
miami.center.latitude = MIA_LATITUDE;
miami.center.longitude = MIA_LONGITUDE;
miami.span.latitudeDelta = SPAN_VALUE;
miami.span.longitudeDelta = SPAN_VALUE;

//Create a circle for miami area
MKCircle *miamiCircle = [MKCircle circleWithCenterCoordinate:miami.center radius:5000];
//2KM or 1.24 miles
[self.mapView addOverlay:miamiCircle];

然后在实现它们的方法中我有这个:

-(MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id<MKOverlay>)overlay
{
    MKCircleView *circleView = [[MKCircleView alloc]initWithCircle:overlay];
    circleView.fillColor = [[UIColor cyanColor] colorWithAlphaComponent:0.5];
    circleView.strokeColor =[[UIColor blueColor] colorWithAlphaComponent:0.6];
    circleView.lineWidth = 1 ;
    return circleView;

    //This is the code for the polygon view but I don't know how
    //to return it without run-time errors 
    //MKPolygonView *polygonView = [[MKPolygonView alloc] initWithPolygon:overlay];
    //polygonView.fillColor = [[UIColor greenColor] colorWithAlphaComponent:0.2];
    //polygonView.strokeColor = [[UIColor greenColor] colorWithAlphaComponent:0.6];
    //polygonView.lineWidth = 1;
    //return polygonView;
}

这看起来已经很糟糕了，因为我在方法中调用了两个 return 语句，但这又是我问这个问题的原因。我不认为错误在于我解析 XML 数据的方式，因为在实现它之前没有错误。谢谢

Answer 1

首先，我想指出您正在使用已弃用的方法。 MKOverlayView 在 iOS7 中已弃用。除此之外，您需要做的是根据传递给委托(delegate)的覆盖参数确定要返回哪种类型的覆盖。所以，如果我要修改你的代码，我会这样做:

-(MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id<MKOverlay>)overlay
{
    if ([overlay isKindOfClass:[MKCircle class]]) {
        MKCircleView *circleView = [[MKCircleView alloc]initWithCircle:overlay];
        circleView.fillColor = [[UIColor cyanColor] colorWithAlphaComponent:0.5];
        circleView.strokeColor =[[UIColor blueColor] colorWithAlphaComponent:0.6];
        circleView.lineWidth = 1 ;
        return circleView;
    } else if ([overlay isKindOfClass:[MKPolygon class]]) {
        MKPolygonView *polygonView = [[MKPolygonView alloc] initWithPolygon:overlay];
        polygonView.fillColor = [[UIColor greenColor] colorWithAlphaComponent:0.2];
        polygonView.strokeColor = [[UIColor greenColor] colorWithAlphaComponent:0.6];
        polygonView.lineWidth = 1;
        return polygonView;
    }

    return nil;
}