在我的应用程序中，我们有一个带有 MKMapView 的屏幕。
此地图显示了一组位置的引脚（位置是在应用程序中定义的模型）。
在模拟器中运行时，这工作正常。但是，当在设备上运行此程序时，几乎每次平移地图时，引脚似乎都会消失并重新出现。即使是轻微的触摸和移动也会导致地图显示和隐藏图钉。
地图不是特别忙，即使显示一个图钉它也会显示和隐藏它。
有谁知道为什么会发生这种情况？我在下面粘贴了我的代码……这是一个 Rubymotion 应用程序，所以代码是用 Ruby 编写的。
- 更新 -
我在下面添加了与此 Ruby 代码等效的 Objective C。抱歉，如果有几个拼写错误或惯用错误，我已经有一段时间没有写任何 OC 了。
- 更新 2 -
看着记录器，我可以看到mapView:viewForAnnotation每次地图针消失/重新出现时都会调用它。
此外，每次mapView:regionDidChangeAnimated我可以看到注释的对象 ID 是相同的 - 所以我认为它们不会被删除（它们不应该被删除）
# ====================
# = MKMapKitDelegate =
# ====================
# Don't react if the user has moved less than three meters
USER_MOVE_THRESHOLD = 3
# The user location has changed
def mapView(mapView, didUpdateUserLocation: newLocation)
NSLog("mapView:didUpdateUserLocation")
return unless userLocation
coord = newLocation.coordinate
newLocationAsCL = CLLocation.alloc.initWithCoordinate(coord, altitude: 1, horizontalAccuracy:1, verticalAccuracy: -1, timestamp: nil)
meters = newLocationAsCL.distanceFromLocation(@lastUserCLLocation)
# If user has moved less than 3m, return
if meters > 0 and meters < USER_MOVE_THRESHOLD
log "Distance was less than #{USER_MOVE_THRESHOLD} meters (#{meters}) - returning ***"
return
end
# If the coord is the same as the previous user location
if userLocation.coordinate.latitude == coord.latitude && userLocation.coordinate.longitude == coord.longitude
log "User hasn't moved - returning ***"
else
log 'User has moved'
end
log "Did update user location: #{coord.latitude},#{coord.longitude}"
if coord.latitude.to_f == 0.0 and coord.longitude.to_f == 0.0
log 'Invalid coordinate received - returning ***'
else
fetchLocationsFromAPI
end
end
def mapView(mapView, regionDidChangeAnimated: animated)
NSLog("mapView:regionDidChangeAnimated:#{animated}")
# do nothing here yet...
end
# create map pins...
def mapView(mapView, viewForAnnotation: annotation)
log "mapView:viewForAnnotation: #{annotation.inspect}"
if annotation.is_a?(Location)
# If there's already an annotation we can use, use it! Otherwise create a new one
annotationView = mapView.dequeueReusableAnnotationViewWithIdentifier(annotation.class.to_s) || begin
annotationView = MKPinAnnotationView.alloc.initWithAnnotation(annotation, reuseIdentifier: annotation.class.to_s)
annotationView.enabled = true
annotationView.canShowCallout = true
annotationView.animatesDrop = false
annotationView.pinColor = MKPinAnnotationColorRed
rightButton = UIButton.buttonWithType(UIButtonTypeDetailDisclosure)
rightButton.addTarget(self, action: 'showLocationScreen:', forControlEvents: UIControlEventTouchUpInside)
annotationView.rightCalloutAccessoryView = rightButton
annotationView
end
annotationView.annotation = annotation
annotationView.rightCalloutAccessoryView.tag = @mapLocations.index(annotation)
return annotationView
end
end
def mapView(mapViewm, didAddAnnotationViews: views)
NSLog("mapView:didAddAnnotationViews - #{views}")
# do nothing here yet...
end
目标 C
#define kUserMoveThreshold 1
-(void)mapView:(MKMapView *)mapView didUpdateUserLocation:(MKUserLocation *)newLocation
{
NSLog(@"mapView:didUpdateUserLocation")
if (!userLocation) {
return;
}
CLLocationCoordinate2D coord = newLocation.coordinate;
CLLocation newLocationAsCL = [[CLLocation alloc] initWithCoordinate: coord altitude: 1 horizontalAccuracy: 1 verticalAccuracy: -1 timestamp: NULL];
CLLocationDistance meters = [newLocationAsCL distanceFromLocation: lastUserCLLocation];
// If user has moved less than 3m, return
if (meters > 0 && meters < kUserMoveThreshold){
NSLog(@"Distance was less than %d meters (%d) - returning ***", kUserMoveThreshold, meters);
return;
}
// If the coord is the same as the previous user location
if (userLocation.coordinate.latitude == coord.latitude && userLocation.coordinate.longitude == coord.longitude){
NSLog(@"User hasn't moved - returning ***");
return;
} else {
NSLog(@"User has moved");
}
NSLog(@"Did update user location: %f,%f", coord.latitude, coord.longitude);
if (coord.latitude == 0.0 && coord.longitude == 0.0){
NSLog(@"Invalid coordinate received - returning ***");
} else {
[self fetchLocationsFromAPI];
}
}
-(void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated
{
NSLog(@"mapView:regionDidChangeAnimated: %s", animated ? @"TRUE" : @"FALSE");
}
-(MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id < MKAnnotation >)annotation
{
NSLog(@"mapView:viewForAnnotation %s", annotation.description);
if ([annotation isKindOfClass: [Location class]]){
// If there's already an annotation we can use, use it! Otherwise create a new one
MKAnnotationView *annotationView = [mapView dequeueReusableAnnotationViewWithIdentifier: [annotation className]];
if (!annotationView){
annotationView = [[MKPinAnnotationView alloc] initWithAnnotation: annotation reuseIdentifier: [annotation className]];
[annotationView setEnabled: YES];
[annotationView setCanShowCallout: YES];
[annotationView setAnimatesDrop: NO];
[annotationView setPinColor: MKPinAnnotationColorRed];
UIButton *rightButton = [UIButton buttonWithType: UIButtonTypeDetailDisclosure];
[rightButton addTarget: self action: @selector(showLocationScreen:) forControlEvents: UIControlEventTouchUpInside];
[annotationView setRightCalloutAccessoryView: rightButton];
}
[annotationView annotation: annotation];
[[annotationView rightCalloutAccessoryView] setTag: [mapLocations indexOfObject: annotation]];
return annotationView
}
}
-(void)mapView:(MKMapView *)mapView didAddAnnotationViews:(NSArray *)views
{
NSLog(@"mapView:didAddAnnotationViews %@", views)
}