拖动标记时不添加标记-谷歌地图iOS应用程序

我正在开发一个iOS谷歌地图。我有以下工作，除了当用户拖动一个标记时，一旦释放标记就不会在那里绘制。我哪里出错了

- (void)clearAllOverlay 
{
[_mapView clear];
[self drawPolygon];
[self addMarker];
}

- (void)addMarker 
{
CLLocationCoordinate2D position;
for (int i = 0; i <= [tappedCoordinates count]-1; i++) {
    position.latitude = [[[tappedCoordinates objectAtIndex:i] objectAtIndex:0] floatValue];
    position.longitude = [[[tappedCoordinates objectAtIndex:i] objectAtIndex:1] floatValue];
    GMSMarker *marker = [[GMSMarker alloc] init];
    marker.position = position;
    marker.map = _mapView;
    marker.icon = [GMSMarker markerImageWithColor:[UIColor blueColor]];
    [marker setDraggable: YES];
}
}
//runs everytime user taps on marker
- (bool)mapView:(GMSMapView *)mapView didTapMarker:(GMSMarker *) marker 
{
[latitudeTappedCoordinates removeObject:[NSNumber numberWithFloat:marker.position.latitude]];
[longitudeTappedCoordinates removeObject:[NSNumber numberWithFloat:marker.position.longitude]];
[self clearAllOverlay];
return 0;
}
//called while marker is dragged
- (void)mapView:(GMSMapView *)mapView didDragMarker:(GMSMarker *) marker 
{
[latitudeTappedCoordinates addObject:[NSNumber numberWithFloat:marker.position.latitude]];
[longitudeTappedCoordinates addObject:[NSNumber numberWithFloat:marker.position.longitude]];

[self clearAllOverlay];
}
//runs everytime user taps on any coordinate, except marker
- (void)mapView:(GMSMapView *)mapView didTapAtCoordinate:(CLLocationCoordinate2D)coordinate
{
// store tapped coordinates in multi-dimensional array
NSArray *array = @[[NSNumber numberWithFloat:coordinate.latitude], [NSNumber numberWithFloat:coordinate.longitude]];
[tappedCoordinates addObject:array];
[latitudeTappedCoordinates addObject:[NSNumber numberWithFloat:coordinate.latitude]];
[longitudeTappedCoordinates addObject:[NSNumber numberWithFloat:coordinate.longitude]];
[self clearAllOverlay];
}

试试这个：

- (void) mapView:(GMSMapView *) mapViewdidEndDraggingMarker:(GMSMarker *)   marker {
    // store tapped coordinates in multi-dimensional array
    NSArray *array = @[[NSNumber numberWithFloat:marker.position.latitude], [NSNumber numberWithFloat:marker.position.longitude]];
    [tappedCoordinates addObject:array];
    [latitudeTappedCoordinates addObject:[NSNumber numberWithFloat:marker.position.latitude]];
    [longitudeTappedCoordinates addObject:[NSNumber numberWithFloat:marker.position.longitude]];
    [self clearAllOverlay];

}