Select Statement Parse Objective C - ios

Question

I have just begun development with 'objective candParse`.
I have a function in my app where I am allowing the user to enter in a new climb.
Data are stored in a table of mine in Parse. I add that climb into the map view portion of my app.
I am wanting to write a select statement that stores all of the results from the query into an array of some sort and then I will dump that into the map view portion. This way I am thinking that it will dynamically add a map pin to the map every time a new area is added, if it does not already exist of course.
I am a .net developer and in this scenario I would grab all the data and then dump it into a data table and real with it from there.... But I am not sure of the best practice on doing this with my above scenario in objective c.
I will post my code for the map below :
MapPin.h
#import <Foundation/Foundation.h>
#import <MapKit/MapKit.h>
#interface MapPin : NSObject <MKAnnotation>
{
CLLocationCoordinate2D coordinate;
NSString *title;
NSString *subtitle;
}
#property (nonatomic, assign) CLLocationCoordinate2D coordinate;
#property (nonatomic, copy) NSString *title;
#property (nonatomic, copy) NSString *subtitle;
#end
MapPin.m
#import "MapPin.h"
#implementation MapPin
#synthesize coordinate, title, subtitle;
#end
MapViewController.h
#import <UIKit/UIKit.h>
#import <MapKit/MapKit.h>
#interface MapViewController : UIViewController
{
MKMapView *mapView;
}
#property (nonatomic, retain) IBOutlet MKMapView *mapView;
-(IBAction)SetMap:(id)sender;
-(IBAction)GetLocation:(id)sender;
-(IBAction)Directions:(id)sender;
#end
MapViewController.m
#import "MapViewController.h"
#import "MapPin.h"
#interface MapViewController ()<MKMapViewDelegate>
#end
#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];
mapView.delegate = self;
//new
//[self.mapView setShowsUserLocation:YES];
//Moss Preserve annotation and map pin
MapPin *MossPreserveAnnotation = [[MapPin alloc] init];
MossPreserveAnnotation.title = #"Moss Rock Preserve Boulder Fields";
MossPreserveAnnotation.subtitle = #"Hoover, AL";
MossPreserveAnnotation.coordinate = CLLocationCoordinate2DMake(33.3816566, -86.8415451);
[mapView addAnnotation:MossPreserveAnnotation];
//Setup map
MKCoordinateRegion mapCoordRegion;
mapCoordRegion.center.latitude = 39;
mapCoordRegion.center.longitude = -97;
mapCoordRegion.span.latitudeDelta = 60.0;
mapCoordRegion.span.longitudeDelta = 60.0;
[mapView setRegion:mapCoordRegion];
}
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
[[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleDefault];
self.navigationController.navigationBar.hidden = NO;
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (void)mapView:(MKMapView *)mapView annotationView:(MKAnnotationView *)view calloutAccessoryControlTapped:(UIControl *)control
{
// Create an MKMapItem to pass to the Maps app
MKPlacemark *placemark = [[MKPlacemark alloc] initWithCoordinate:view.annotation.coordinate
addressDictionary:nil];
MKMapItem *MapItem = [[MKMapItem alloc] initWithPlacemark:placemark];
[MapItem setName:view.annotation.title];
NSDictionary *launchOptions = #{MKLaunchOptionsDirectionsModeKey : MKLaunchOptionsDirectionsModeDriving};
// Get the "Current User Location" MKMapItem
MKMapItem *currentLocationItem = [MKMapItem mapItemForCurrentLocation];
[MKMapItem openMapsWithItems:#[currentLocationItem, MapItem]
launchOptions:launchOptions];
}
- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation
{
MKAnnotationView *annotationView = [[MKPinAnnotationView alloc] initWithAnnotation:annotation
reuseIdentifier:#"MKPinAnnotationView"];
annotationView.canShowCallout = YES;
UIButton *detailButton = [UIButton buttonWithType:UIButtonTypeInfoLight];
[detailButton setTintColor:[UIColor colorWithRed:183/255.0 green:207/255.0 blue:85/255.0 alpha:0.5]];
annotationView.rightCalloutAccessoryView = detailButton;
return annotationView;
}
-(IBAction)SetMap:(id)sender;
{
switch (((UISegmentedControl *) sender).selectedSegmentIndex)
{
case 0:
mapView.mapType = MKMapTypeStandard;
break;
case 1:
mapView.mapType = MKMapTypeSatellite;
break;
case 2:
mapView.mapType = MKMapTypeHybrid;
break;
default:
break;
}
}
-(IBAction)GetLocation:(id)sender;
{
mapView.showsUserLocation = YES;
}
-(IBAction)Directions:(id)sender;
{
NSString *urlString = #"http://maps.apple.com/maps?daddr=33.3816566,-86.8415451";
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:urlString]];
}
#end
Sorry to dump a lot of code in here... Just wanted to provide everyone with what I had.

Answer 1

Before answering, some notes:
Start methods in lower case, it's a common practice.
A pin and an annotation are two diferent concepts, let's say a pin is the view and an annotation is the model (or business object), so it's better if you call MapPin like MapAnnontation (or just Annontation, cause Map is redundant). Probably in a close future you are going to have custom pins, that are a subclass of MKAnnotationView.
For your reply, I have an app that retrieves places for the current map area from Parse (www.sharewifiapp.com). This is the code and below some explanations:
#pragma mark MKMapViewDelegate
- (void)mapView:(MKMapView *)mapView regionWillChangeAnimated:(BOOL)animated {
[self.hotspotsQuery cancel];
}
- (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated {
//DDDebugLog(#"zoom %lu", (unsigned long)[self.mapView zoomLevel]);
// retrieve all hotspots using the filtering and the current view port
self.hotspotsQuery = [PFQuery queryWithClassName:[SWHotspot parseClassName]];
MKMapRect mRect = self.mapView.visibleMapRect;
MKMapPoint neMapPoint = MKMapPointMake(MKMapRectGetMaxX(mRect), mRect.origin.y);
MKMapPoint swMapPoint = MKMapPointMake(mRect.origin.x, MKMapRectGetMaxY(mRect));
CLLocationCoordinate2D neCoord = MKCoordinateForMapPoint(neMapPoint);
CLLocationCoordinate2D swCoord = MKCoordinateForMapPoint(swMapPoint);
PFGeoPoint* swGeoPoint=[PFGeoPoint geoPointWithLatitude:swCoord.latitude longitude:swCoord.longitude];
PFGeoPoint* neGeoPoint=[PFGeoPoint geoPointWithLatitude:neCoord.latitude longitude:neCoord.longitude];
[self.hotspotsQuery whereKey:#"location" withinGeoBoxFromSouthwest:swGeoPoint toNortheast:neGeoPoint];
[self.hotspotsQuery includeKey:#"owner"];
[self.hotspotsQuery orderByDescending:#"updatedAt"];
self.hotspotsQuery.limit=1000;
self.loadingHotspotsActivityView.hidden=NO;
[self.hotspotsQuery findObjectsInBackgroundWithBlock:^(NSArray *hotspots, NSError *error) {
self.loadingHotspotsActivityView.hidden=YES;
if (error) {
DDLogError(#"Error retrieving hotspots: %#", [error userInfo][#"error"]);
} else {
// TEST.
/*
NSLog(#"retrieved: %lu", (unsigned long)objects.count);
[self.mapView removeAnnotations:self.mapView.annotations];
[self.mapView addAnnotations:objects];
*/
// remove hotspots that are not in the current response (hotstpots)
NSMutableArray* hotspotsToRemove=[self.mapView.annotations mutableCopy];
[hotspotsToRemove removeObjectsInArray:hotspots];
[self.mapView removeAnnotations:hotspotsToRemove];
// add hotpots from the current response that were not in the original set
NSMutableArray* hotspotsToAdd=[hotspots mutableCopy];
[hotspotsToAdd removeObjectsInArray:self.mapView.annotations];
[self.mapView addAnnotations:hotspotsToAdd];
}
}];
}
Important points:
-Save your parse query so you can cancel it.
-Cancel it when user starts moving the map, and launch a new request when user stops moving the map.
-Every time you receive new places from parse query, you can remove all annotations and put the new ones, but from a performance point of view that's not nice. If you want that try my code where it says TEST.
-If you want to improve performance, follow my logic, that removes annotations that are not in the current reply and only add new places if they are not in the map.
Hope this helps.