MKOverlay没有顺利调整大小

Question

我已经将MKCircle作为MKOverlay添加到我的MKMapView中.我还添加了一个UISlider来决定圆的半径.不幸的是,当使用它时,它似乎有点"滞后",不像我想要的那样流畅.

示例:http: //dl.dropbox.com/u/3077127/mkoverlayDelay.mov

这是我的代码:

- (void)addCircle
{
    // draw the radius circle for the marker
    double radius = 2000.0;
    MKCircle *circle = [MKCircle circleWithCenterCoordinate:location radius:radius];
    [circle setTitle:@"background"];
    [mapView addOverlay:circle];

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

- (void)addCircleWithRadius:(double)radius
{
    MKCircle *circle = [MKCircle circleWithCenterCoordinate:location radius:radius];
    [circle setTitle:@"background"];
    [mapView addOverlay:circle];

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

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

    double radius = (sender.value * 100);

    [self addCircleWithRadius:radius];
}

- (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;
}

有没有人对我如何平滑这个有什么建议？

最诚挚的问候,
Paul Peelen

Answer 1

我已经尝试过你的代码,并找到了一种非常简单的方法来使它更顺畅.

如果您更改了以下呼叫的顺序: - (void)sliderChanged:(UISlider*)sender

你可以打电话 [self addCircleWithRadius:radius];

在打电话之前 [mapView removeOverlays:[mapView overlays]];

只是确保你不要删除刚添加的叠加层,只删除旧的叠层层.

这将为您提供更平滑的调整大小,特别是当新圆圈小于旧圆圈时.

对于较大的圆圈,您可能最好使用NSOperations以确保更快地创建视图,这将使其更加平滑.

希望这可以帮助.