How to keep a reference of marker in iOS Google Maps

问题

So according to the documentation, I need to keep a reference to the marker. Right now, in my viewWillDisappear method I'm trying to clear one of the pins off the map but it's not working. Maybe it's because I don't have a reference to it? If so, how does that work? (By the way, I couldn't get it to work as a part of any other method as well, not just viewWillDisappear.)

I have the latitude and longitude of the marker and here's what I'm doing now:

CLLocationCoordinate2D position = CLLocationCoordinate2DMake([[passedCoordinates objectAtIndex:0]doubleValue], [[passedCoordinates objectAtIndex:1]doubleValue]);
GMSMarker *marker = [GMSMarker markerWithPosition:position];
marker.map = nil;

But it's not clearing. Any advice?

Update:

I'm keeping a reference now and this is how I'm trying to find which marker to clear:

- (void)viewWillDisappear:(BOOL)animated{
    [super viewWillDisappear:YES];
    if (passedCoordinates.count != 0) {
        for (GMSMarker *markerRef in _markerRefs){
            if (markerRef.position.latitude == [[passedCoordinates objectAtIndex:0]doubleValue] && markerRef.position.longitude == [[passedCoordinates objectAtIndex:1] doubleValue]) {
                NSLog(@"here");
                markerRef.map = nil;
            }
        }
    }
}

I get the log output that it's finding the correct marker but it's not going away. I added a button on the navigation bar just to click and remove the marker with the same function but it's still on the map.

回答1:

When you call markerWithPosition: its creating a new object with given position. It will not return your old marker object's pointer with that position. When you creating your markers, you should keep it in an array:

@interface YourClass()

// Declaring array that will hold all markers
@property (strong, nonatomic) NSMutableArray *allMarkers;

//...
@end

@implementation

//...
- (void)yourMethod
{
     if (!self.allMarkers) {
         self.allMarkers = [[NSMutableArray alloc] init];
     }

   // Here, when you creating your markers and adding to self.mapView
      CLLocationCoordinate2D position = CLLocationCoordinate2DMake([[passedCoordinates objectAtIndex:0]doubleValue], [[passedCoordinates objectAtIndex:1]doubleValue]);
GMSMarker *marker = [GMSMarker markerWithPosition:position];
      marker.map  = self.mapView;

   // add allocated markers to allMarkers array
     [self.allMarkers addObject:marker]
}

//...
- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];

    for (GMSMarker *marker in self.allMarkers) {
        // Remove marker from the map
        marker.map = nil;
    }
}

来源：https://stackoverflow.com/questions/24343769/how-to-keep-a-reference-of-marker-in-ios-google-maps