Question

我需要 circle一个圈子,以显示我所策划的距离。

我在什么地方执行这两条法典,使之发挥作用? 我尝试将其列入<条码>viewWillAppear:,但圈子没有出现。

[self addCircle:_coordinate];
[self addCircleWithRadius:5.5 addCircleWithCoordinate:_coordinate];

- (void)addCircle: (CLLocationCoordinate2D)coordinate
{
    // draw the radius circle for the marker

    double radius = 2000.0;
    MKCircle *circle = [MKCircle circleWithCenterCoordinate:coordinate radius:radius];
    [circle setTitle:@"background"];
    [_mapView addOverlay:circle];

    MKCircle *circleLine = [MKCircle circleWithCenterCoordinate:coordinate radius:radius];
    [circleLine setTitle:@"line"];
    [_mapView addOverlay:circleLine];
}

- (void)addCircleWithRadius:(double)radius addCircleWithCoordinate: (CLLocationCoordinate2D) coordinate
{

    MKCircle *circle = [MKCircle circleWithCenterCoordinate:coordinate radius:radius];
    [circle setTitle:@"background"];
    [_mapView addOverlay:circle];

    MKCircle *circleLine = [MKCircle circleWithCenterCoordinate:coordinate radius:radius];
    [circleLine setTitle:@"line"];
    [_mapView addOverlay:circleLine];
}

- (void)sliderChanged:(UISlider*)sender
{
    [_mapView removeOverlays:[_mapView overlays]];

    double radius = (sender.value * 100);
    CLLocationCoordinate2D coordinate = self.coordinate;

    [self addCircleWithRadius:radius addCircleWithCoordinate:coordinate];
}

- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id <MKOverlay>)overlay{
    MKCircle *circle = overlay;
    MKCircleView *circleView = [[[MKCircleView alloc] initWithCircle:overlay] autorelease];

    if ([circle.title isEqualToString:@"background"])
    {
        //circleView.fillColor = UIColorFromRGB(0x598DD3);
        circleView.alpha = 0.25;
    }
    else
    {
        //circleView.strokeColor = UIColorFromRGB(0x5C8AC7);
        circleView.lineWidth = 2.0;
    }

    return circleView;
}

Answer 1

虽然你可以尝试<代码>viewDidAppear,而不是viewWillAppear,但我认为它已经在这方面开展工作。我认为,你有别的错误,你应该与一位gger者一道找到。检查通常嫌疑人:

Set the fill color. Make it opaque and obvious.
_mapView might be nil or zombied during runtime. (or not mapped in your xib)
The coordinates or radius may be different than you expect. Check the actual coordinate values in your debugger.
Everything may be correct except that the coordinates are not located in your map s zoomed area.

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