使用UI滑块动态更改MKCircle半径

Question

我现在正在和MapView一起做一个项目。您可以按住Tab键并按住键来放置别针。当你选择大头针时，会出现一个具有一定半径的圆。但是现在用户应该决定圆的半径是多少。这应该可以通过UISlider来实现。

问题是，圆的半径不是动态变化的。圆圈出现了，你移动滑块，什么也不会发生。取消选择并再次选择引脚，将添加另一个具有新UISlider值的环。

当前代码:在.h文件中：

@property (retain, nonatomic) MKCircle *pinCircle;

在.m文件中：

-(void)mapView:(MKMapView *)mapView didSelectAnnotationView:(MKAnnotationView *)view {

    _radius.hidden= false;

    CLLocation *pinLocation = [[CLLocation alloc] initWithLatitude:[(MKPointAnnotation*)[view annotation] coordinate].latitude longitude:[(MKPointAnnotation*)[view annotation] coordinate].longitude];
    _pinCircle = [MKCircle circleWithCenterCoordinate:pinLocation.coordinate radius:_radius.value*1000];
    [_mapView addOverlay:_pinCircle];
    [_pinCircle autorelease];

}

-(void)mapView:(MKMapView *)mapView didDeselectAnnotationView:(MKAnnotationView *)view {
    _radius.hidden= true;
    }

- (MKOverlayView *)mapView:(MKMapView *)map viewForOverlay:(id <MKOverlay>)overlay
{
    MKCircleView *circleView = [[MKCircleView alloc] initWithOverlay:overlay];
    circleView.strokeColor = [UIColor greenColor];
    circleView.fillColor = [[UIColor greenColor] colorWithAlphaComponent:0.4];
    return [circleView autorelease];
}

我知道我必须使用这个操作：

- (IBAction)radiusSliderChange:(id)sender {
    NSLog(@"Slidervalue changed");
    [self.pinCircle removeFromSuperview];
}

但这会导致以下错误：

-[MKCircle removeFromSuperview]: unrecognized selector sent to instance 0x18b919d0

根据Alejandro F. Carrera的文章，我得到了以下错误：

https://www.dropbox.com/s/saxhns992jex606/Bildschirmfoto%202014-09-04%20um%2020.20.21.png?dl=0

Answer 1

您必须在初始化时设置为nil (pinCircle = nil;)，然后必须检查以下内容：

-(void)mapView:(MKMapView *)mapView didSelectAnnotationView:(MKAnnotationView *)view
{
   if(pinCircle != nil) // click two annotations
   {
      [_mapView removeOverlay: _pinCircle];
       _pinCircle = nil;
   }
   _radius = 100; // start value to define
   [self createCircle: view.annotation.coordinate];
}

-(void)mapView:(MKMapView *)mapView didDeselectAnnotationView:(MKAnnotationView *)view 
{
    if(pinCircle != nil)
    {
       [_mapView removeOverlay: _pinCircle];
       _pinCircle = nil;
    }
}

- (MKOverlayView *)mapView:(MKMapView *)map viewForOverlay:(id <MKOverlay>)overlay
{
    MKCircleView *circleView = [[MKCircleView alloc] initWithOverlay:overlay];
    circleView.strokeColor = [UIColor greenColor];
    circleView.fillColor = [[UIColor greenColor] colorWithAlphaComponent:0.4];
    return [circleView autorelease];
}

你已经使用了故事板，所以你必须有像pinCircle这样的滑块变量

- (IBAction)radiusSliderChange:(id)sender {
    _radius = _slider.value;  // radius property of circle is readonly so you must create other one
    [_mapView removeOverlay: _pinCircle];
    [self createCircle:_pinCircle.coordinate];
}

- (void)createCircle:(CLLocationCoordinate)coord
{
    _pinCircle = [MKCircle circleWithCenterCoordinate:coord radius:_radius.value*1000];
    [_mapView addOverlay:_pinCircle];
    [_pinCircle autorelease];
}

Answer 2

你可以在.h文件中访问你的MKCircle *pinCircle，然后像"self.pinCircle“一样访问它。在此之后，您将能够使用[self.pinCircle removeFromSuperview];删除它。:-)

Answer 3

在滑块值更改后，您需要删除之前添加的覆盖。

  - (IBAction)sliderForJixRadiusValueChanged:(id)sender {
    //    self.mapSelectorManager.circleRadius = self.sliderForJixRadius.value;

        [_mapView removeOverlays:arrOverlay];

        MKCircle *circle= [MKCircle circleWithCenterCoordinate:_droppedAt1 radius: (_sliderForJixRadius.value)*10000];
        [_mapView addOverlay:circle];
        [arrOverlay addObject:circle];