ios - 使用 UI slider 动态更改 MKCircle 半径

我现在正在使用 MapView 进行一个项目。您可以通过 Tab 放置图钉并按住。当您选择引脚时，将出现一个具有一定半径的圆。但现在用户应该决定圆的半径。这应该可以通过 UISlider 实现。

问题是，圆的半径不会动态变化。圆圈出现，您移动 slider ，没有任何反应。取消选择并再次选择引脚，将添加具有新 UISlider 值的另一个环。

当前代码: 在 .h 文件中:

@property (retain, nonatomic) MKCircle *pinCircle;

在 .m 文件中:

-(void)mapViewMKMapView *)mapView didSelectAnnotationViewMKAnnotationView *)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)mapViewMKMapView *)mapView didDeselectAnnotationViewMKAnnotationView *)view {
    _radius.hidden= true;
    }

- (MKOverlayView *)mapViewMKMapView *)map viewForOverlayid <MKOverlay>)overlay
{
    MKCircleView *circleView = [[MKCircleView alloc] initWithOverlayverlay];
    circleView.strokeColor = [UIColor greenColor];
    circleView.fillColor = [[UIColor greenColor] colorWithAlphaComponent:0.4];
    return [circleView autorelease];
}

我知道我必须使用这个 Action :

- (IBAction)radiusSliderChangeid)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 的帖子，我收到以下错误:

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

---

Best Answer-推荐答案

你必须在初始化时设置为 nil (pinCircle = nil;) 然后你必须检查这个:

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

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

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

你已经为此使用了 Storyboard，所以你必须有像 pinCircle 这样的 slider 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];
}

关于ios - 使用 UI slider 动态更改 MKCircle 半径，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/25671328/