C ++中的跨平台GUI窗口(Cross platform GUI window in C++)

 我看到可能与之相关的错误。 每次遍历for循环中的locations数组时，都会覆盖markersArray。 实例化for循环之外的markersArray。 
 
 你能尝试NSLog你想要绘制的每个标记的坐标吗？ 
 
 如果坐标相同，则标记应该正好在彼此的顶部绘制，使得看起来标记被覆盖，但它们只是在彼此之上。 
 
 完成后记录位置和markersArray的计数，以确保它们等于快速检查。 
 
 *编辑：我看到你的问题。 每次迭代for循环时，都会覆盖MapView。 
 
 尝试这样的事情： 
 
// Create a markersArray property
@property (nonatomic, strong) NSMutableArray *markersArray;
// Create a GMSMapView property
@property (nonatomic, strong) GMSMapView *mapView_;

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self setupMapView];
    [self plotMarkers];
}

// Lazy load the getter method
- (NSMutableArray *)markersArray
{
    if (!_markersArray) {
        _markersArray = [NSMutableArray array];
    }
    return _markersArray;
}

- (void)setupMapView
{
    self.mapView_ = [GMSMapView mapWithFrame:CGRectZero camera:camera];
    self.view = self.mapView_;
    self.mapView_.myLocationEnabled = YES;
    self.mapView_.mapType = kGMSTypeHybrid;
    self.mapView_.settings.myLocationButton = YES;
    self.mapView_.settings.zoomGestures = YES;
    self.mapView_.settings.tiltGestures = NO;
    self.mapView_.settings.rotateGestures = NO;

    // You also instantiate a GMSCameraPosition class, but you don't add it to your mapview
    GMSCameraPosition *camera = [GMSCameraPosition cameraWithLatitude:40.0823
                                                            longitude:-74.2234
                                                                 zoom:7];

}

- (void)plotMarkers
{
    // I don't know how you're creating your locations array, so I'm just pretending
    // an array will be returned from this fake method
    NSArray *locations = [self loadLocations];
    for (int i=0; i<[locations count]; i++){

        NSString *lat = [[locations objectAtIndex:i] objectAtIndex:0];
        NSString *lon = [[locations objectAtIndex:i] objectAtIndex:1];
        double lt=[lat doubleValue];
        double ln=[lon doubleValue];
        NSString *name = [[locations objectAtIndex:i] objectAtIndex:2];

        // Instantiate and set the GMSMarker properties
        GMSMarker *marker = [[GMSMarker alloc] init];
        marker.appearAnimation=YES;
        marker.position = CLLocationCoordinate2DMake(lt,ln);
        marker.title = name;
        marker.snippet = [[locations objectAtIndex:i] objectAtIndex:3];
        marker.map = self.mapView_;

        [self.markersArray addObject:marker];

    }
}

I see something wrong that's possibly related. You're overwriting markersArray every time you iterate through the locations array in the for loop. Instantiate markersArray outside of the for loop.
 
Could you try to NSLog the coordinates of each marker you're trying to plot?
 
If the coordinates are the same, the marker should plot right on top of each other making it appear that markers are being overridden, but they're just on top of each other.
 
Log the count of the locations and markersArray after you're done to make sure they're equal to each as a quick check.
 
*Edit: I see your problem. You're overriding your MapView every time you iterate through your for loop.
 
Try something like this:
 
// Create a markersArray property
@property (nonatomic, strong) NSMutableArray *markersArray;
// Create a GMSMapView property
@property (nonatomic, strong) GMSMapView *mapView_;

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self setupMapView];
    [self plotMarkers];
}

// Lazy load the getter method
- (NSMutableArray *)markersArray
{
    if (!_markersArray) {
        _markersArray = [NSMutableArray array];
    }
    return _markersArray;
}

- (void)setupMapView
{
    self.mapView_ = [GMSMapView mapWithFrame:CGRectZero camera:camera];
    self.view = self.mapView_;
    self.mapView_.myLocationEnabled = YES;
    self.mapView_.mapType = kGMSTypeHybrid;
    self.mapView_.settings.myLocationButton = YES;
    self.mapView_.settings.zoomGestures = YES;
    self.mapView_.settings.tiltGestures = NO;
    self.mapView_.settings.rotateGestures = NO;

    // You also instantiate a GMSCameraPosition class, but you don't add it to your mapview
    GMSCameraPosition *camera = [GMSCameraPosition cameraWithLatitude:40.0823
                                                            longitude:-74.2234
                                                                 zoom:7];

}

- (void)plotMarkers
{
    // I don't know how you're creating your locations array, so I'm just pretending
    // an array will be returned from this fake method
    NSArray *locations = [self loadLocations];
    for (int i=0; i<[locations count]; i++){

        NSString *lat = [[locations objectAtIndex:i] objectAtIndex:0];
        NSString *lon = [[locations objectAtIndex:i] objectAtIndex:1];
        double lt=[lat doubleValue];
        double ln=[lon doubleValue];
        NSString *name = [[locations objectAtIndex:i] objectAtIndex:2];

        // Instantiate and set the GMSMarker properties
        GMSMarker *marker = [[GMSMarker alloc] init];
        marker.appearAnimation=YES;
        marker.position = CLLocationCoordinate2DMake(lt,ln);
        marker.title = name;
        marker.snippet = [[locations objectAtIndex:i] objectAtIndex:3];
        marker.map = self.mapView_;

        [self.markersArray addObject:marker];

    }
}