iPad Mapkit - 更改“当前位置”的标题

Question

在地图视图中，我显示当前用户位置。单击图钉后，其显示“当前位置”。我想将其更改为“我当前的位置”。我该如何改变它。 我还想更改计时器中当前用户位置图钉的颜色。比如每隔一秒它的颜色就会在绿色、紫色和红色之间变化。可以做吗？

我使用地图套件的显示默认位置，然后按如下方式操作注释图钉颜色：

- (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

如果您让地图视图显示用户位置的默认注释视图（蓝点），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，则需要做更多的工作。

一、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视图，则应将图钉颜色更改代码放入自定义视图中。定期更改颜色的一种方法是使用 PerformSelector:withObject:afterDelay:。在 SolarAnnotationView.m 中，添加这两个方法：

-(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];
}

同时将方法标头添加到 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;
}