About the Tab bar button with NSMutableArray annotation in MapKit - ios

Question

I have created 4 type of annotation group. In the map UI, I also added a tab bar on the bottom as my button.
My tab bar is used to filter out the annotation in MapKit.
For example... I have 4 group of annotation and 4 tab bar item.
When I clicked tab bar item 1, it show only 1 group of annotation in MapKit, other group of annotation will hide/remove in MapKit but I failed to achieve this kind of work.
My code:
in MapViewController.h
#import <UIKit/UIKit.h>
#import <MapKit/MapKit.h>
#import <CoreLocation/CoreLocation.h>
#interface MapViewController : UIViewController <MKMapViewDelegate, CLLocationManagerDelegate , UITabBarDelegate>{
IBOutlet UITabBar *tabBar;
}
#property (weak, nonatomic) IBOutlet UIBarButtonItem *sidebarButton;
#property (weak, nonatomic) IBOutlet MKMapView *mapView;
#property (strong, nonatomic) CLLocationManager *locationManager;
#end
my mapViewController.m:
#import "MapViewController.h"
#import "SWRevealViewController.h"
#import "Annotation.h"
#interface MapViewController ()<CLLocationManagerDelegate>
#end
//set desitination of map
#define PENANG_LATI 5.419501;
#define PENANG_LONG 100.323264;
//shop
#define SHOP_LATI 5.419501;
#define SHOP_LONG 100.323264;
//cafe
#define CAFE_LATI 5.419917;
#define CAFE_LONG 100.322969;
//food
#define FOOD_LATI 5.419746;
#define FOOD_LONG 100.322610;
//mural
#define MURAL_LATI 5.419786;
#define MURAL_LONG 100.322510;
#define THE_SPAN 0.005f;
#implementation MapViewController
#synthesize mapView;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
//tabBar
tabBar.delegate = self;
MKCoordinateRegion myRegion;
//Center
CLLocationCoordinate2D center;
center.latitude = PENANG_LATI;
center.longitude = PENANG_LONG;
//SPAN
MKCoordinateSpan span;
span.latitudeDelta = THE_SPAN;
span.longitudeDelta = THE_SPAN;
myRegion.center = center;
myRegion.span = span;
//set map
[mapView setRegion:myRegion animated:YES];
SWRevealViewController *revealViewController = self.revealViewController;
if ( revealViewController )
{
[self.sidebarButton setTarget: self.revealViewController];
[self.sidebarButton setAction: #selector( revealToggle: )];
[self.view addGestureRecognizer:self.revealViewController.panGestureRecognizer];
}
/*
//create coordinate
CLLocationCoordinate2D penangLocation;
penangLocation.latitude = PENANG_LATI;
penangLocation.longitude = PENANG_LONG;
Annotation * myAnnotation = [Annotation alloc];
myAnnotation.coordinate = penangLocation;
myAnnotation.title = #"THE ONE ACADEMY PENANG";
myAnnotation.subtitle = #"HELLO!! I STUDY HERE";
[self.mapView addAnnotation:myAnnotation];
*/
}
- (void)tabBar:(UITabBar *)tabBar didSelectItem:(UITabBarItem *)item
{
//my group of annotation location
NSMutableArray * myShop = [[NSMutableArray alloc] init];
NSMutableArray * myCafe = [[NSMutableArray alloc] init];
NSMutableArray * myFood = [[NSMutableArray alloc] init];
NSMutableArray * myMural = [[NSMutableArray alloc] init];
CLLocationCoordinate2D penangLocation;
Annotation * myShopAnnotation;
Annotation * myCafeAnnotation;
Annotation * myFoodAnnotation;
Annotation * myMuralAnnotation;
//shop location
myShopAnnotation = [[Annotation alloc] init];
penangLocation.latitude = SHOP_LATI;
penangLocation.longitude = SHOP_LONG;
myShopAnnotation.coordinate = penangLocation;
myShopAnnotation.title = #"Shop";
myShopAnnotation.subtitle = #"I study here";
[myShop addObject:myShopAnnotation];
//cafe location
myCafeAnnotation = [[Annotation alloc] init];
penangLocation.latitude = CAFE_LATI;
penangLocation.longitude = CAFE_LONG;
myCafeAnnotation.coordinate = penangLocation;
myCafeAnnotation.title = #"Cafe";
myCafeAnnotation.subtitle = #"I paid here";
[myCafe addObject:myCafeAnnotation];
//food location
myFoodAnnotation = [[Annotation alloc] init];
penangLocation.latitude = FOOD_LATI;
penangLocation.longitude = FOOD_LONG;
myFoodAnnotation.coordinate = penangLocation;
myFoodAnnotation.title = #"Food";
myFoodAnnotation.subtitle = #"I walk here";
[myFood addObject:myFoodAnnotation];
//Mural location
myMuralAnnotation = [[Annotation alloc] init];
penangLocation.latitude = MURAL_LATI;
penangLocation.longitude = MURAL_LONG;
myMuralAnnotation.coordinate = penangLocation;
myMuralAnnotation.title = #"Mural";
myMuralAnnotation.subtitle = #"I walk here";
[myMural addObject:myMuralAnnotation];
if(item.tag == 1)
{
//show and hide annotation
NSLog(#"shop");
[mapView addAnnotations:myShop];
[mapView removeAnnotations:myCafe];
[mapView removeAnnotations:myFood];
[mapView removeAnnotations:myMural];
}
if(item.tag == 2)
{
//show and hide annotation
NSLog(#"cafe");
[mapView removeAnnotations:myShop];
[mapView addAnnotations:myCafe];
[mapView removeAnnotations:myFood];
[mapView removeAnnotations:myMural];
}
if(item.tag == 3)
{
//show and hide annotation
NSLog(#"food");
[mapView removeAnnotations:myShop];
[mapView removeAnnotations:myCafe];
[mapView removeAnnotations:myFood];
[mapView addAnnotations:myMural];
}
if(item.tag == 4)
{
//show and hide annotation
NSLog(#"mural");
[mapView removeAnnotations:myShop];
[mapView removeAnnotations:myCafe];
[mapView removeAnnotations:myFood];
[mapView addAnnotations:myMural];
}
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end

Answer 1

When removeAnnotations: is called like this:
[mapView removeAnnotations:myCafe];
the map view looks for the exact objects (using pointer comparison) in myCafe that are already on the map.
The map view here does not match up annotations using their coordinate, title, etc.
Since the code creates new instances of each annotation every time a selection is made, the new instances are not found on the map and so removeAnnotations: does nothing.
Instead, in your case, you could just tell the map view to remove all existing annotations and then add the new annotations based on the current selection.
Instead of this:
[mapView addAnnotations:myShop];
[mapView removeAnnotations:myCafe];
[mapView removeAnnotations:myFood];
[mapView removeAnnotations:myMural];
do this:
[mapView removeAnnotations:mapView.annotations]; //remove all
[mapView addAnnotations:myShop]; //then add new
The code could be simplified as well by using a switch statement and in each case, only create the annotations needed for the selection (you don't need to create all annotations every time).