iPad Mapkit - 更改标题 "Current Location"

Question

在 map View 中，我显示当前用户位置。单击图钉上显示的“当前位置”。我想将其更改为“我的当前位置”。我怎样才能改变它。
我还想在计时器中更改当前用户位置图钉颜色。像每一秒它都应该在绿色、紫色和红色之间改变颜色。有可能做到吗？

我正在使用 map 套件的显示默认位置，然后操作注释图钉颜色如下:

- (MKAnnotationView *)mapView:(MKMapView *)map viewForAnnotation:(id <MKAnnotation>)annotation{
static NSString *AnnotationViewID = @"annotationViewID";
SolarAnnotationView* annotationView = (SolarAnnotationView*)[map dequeueReusableAnnotationViewWithIdentifier:AnnotationViewID];
if(annotationView == nil)
{
    if([self CLLocationCoordinate2DEquals:mapView.userLocation.location.coordinate withSecondCoordinate:[annotation coordinate]]) //Show current location with green pin
    {
        annotationView = [[SolarAnnotationView alloc] initWithAnnotation:annotation];
        annotationView.delegate = self;
        [annotationView setPinColor:MKPinAnnotationColorGreen];
    }
    else
    {
        annotationView = [[SolarAnnotationView alloc] initWithAnnotation:annotation];
        annotationView.delegate = self;
    }
}   

return annotationView;

}

- (BOOL) CLLocationCoordinate2DEquals:(const CLLocationCoordinate2D)lhs withSecondCoordinate:(const CLLocationCoordinate2D) rhs{
const CLLocationDegrees DELTA = 0.001;
return fabs(lhs.latitude - rhs.latitude) <= DELTA && fabs(lhs.longitude - rhs.longitude) <= DELTA;

}

Answer 1

如果您让 map View 显示用户位置(蓝点)的默认注释 View ，则实现起来会更简单(并且您会得到一个漂亮的蓝点，带有很酷的动画缩放圆圈)。

如果您必须使用图钉图像而不是蓝点来显示用户位置，则需要做更多工作。

首先，使用蓝点的简单方法:

- (MKAnnotationView *)mapView:(MKMapView *)map viewForAnnotation:(id <MKAnnotation>)annotation{
    if ([annotation isKindOfClass:[MKUserLocation class]])
    {
        ((MKUserLocation *)annotation).title = @"My Current Location";
        return nil;  //return nil to use default blue dot view
    }

    //Your existing code for viewForAnnotation here (with some corrections)...
    static NSString *AnnotationViewID = @"annotationViewID";
    SolarAnnotationView* annotationView = (SolarAnnotationView*)[map dequeueReusableAnnotationViewWithIdentifier:AnnotationViewID];
    if(annotationView == nil)
    {
        {
            annotationView = [[[SolarAnnotationView alloc] initWithAnnotation:annotation] autorelease];
            //added autorelease above to avoid memory leak
            annotationView.delegate = self;
        }
    }

    //update annotation in view in case we are re-using a view
    annotationView.annotation = annotation;

    return annotationView;
}

如果您想对用户位置使用自定义注释 View ，则应将引脚颜色更改代码放在自定义 View 中。定期更改颜色的一种方法是使用 performSelector:withObject:afterDelay:。在 SolarAnnotationView.m 中，添加以下两个方法:

-(void)startChangingPinColor
{
    switch (self.pinColor) {
        case MKPinAnnotationColorRed:
            self.pinColor = MKPinAnnotationColorGreen;
            break;
        case MKPinAnnotationColorGreen:
            self.pinColor = MKPinAnnotationColorPurple;
            break;
        default:
            self.pinColor = MKPinAnnotationColorRed;
            break;
    }
    [self performSelector:@selector(startChangingPinColor) withObject:nil afterDelay:1.0];
}

-(void)stopChangingPinColor
{
    [NSObject cancelPreviousPerformRequestsWithTarget:self];
}

还将方法头添加到 SolarAnnotationView.h 文件中。

然后像这样更改 viewForAnnotation 方法:

- (MKAnnotationView *)mapView:(MKMapView *)map viewForAnnotation:(id <MKAnnotation>)annotation{
    static NSString *AnnotationViewID = @"annotationViewID";
    SolarAnnotationView* annotationView = (SolarAnnotationView*)[map dequeueReusableAnnotationViewWithIdentifier:AnnotationViewID];
    if(annotationView == nil)
    {
        {
            annotationView = [[[SolarAnnotationView alloc] initWithAnnotation:annotation] autorelease];
            annotationView.delegate = self;
        }
    }

    //Update annotation in view in case we are re-using a view...
    annotationView.annotation = annotation;

    //Stop pin color changing in case we are re-using a view that has it on
    //and this annotation is not user location...
    [annotationView stopChangingPinColor];

    if([self CLLocationCoordinate2DEquals:mapView.userLocation.location.coordinate withSecondCoordinate:[annotation coordinate]]) //Show current location with green pin
    {
        [annotationView setPinColor:MKPinAnnotationColorGreen];
        annotationView.canShowCallout = YES;
        ((MKPointAnnotation *)annotation).title = @"My Current Location";
        [annotationView startChangingPinColor];
    }

    return annotationView;
}