ios - 将 Parse PFGeoPoints 数组显示为 map 注释错误

Question

我试图在 map 上显示存储在 NSArray 中的对象。在执行获取用户 2 英里范围内位置的方法后，这些对象是从名为 Affiliates 的 Parse.com 类中提取的。我已经使用 NSLog 来确认查询正在正确执行，所以我知道提取也正在正确执行。

当我尝试运行该应用程序时，我在 for(NSDictionary) 部分抛出一个错误并且该应用程序卡住。错误状态为“Thread 1: EXC_BAD_ACCESS (access code 1, address 0x80120)” 在咨询了 Google 后我发现这是某种类型的内存分配问题，但我不知道它为什么会发生或如何修复它。

#import "ViewController.h"
#import "MapAnnotation.h"

@import CoreLocation;

@interface ViewController () <CLLocationManagerDelegate>

@property (nonatomic,strong) NSArray *affiliates;

@end

@implementation ViewController

- (void)viewDidLoad {


    [super viewDidLoad];

    // Ask for authorization to collect location from user
    CLLocationManager * locationManager = [[CLLocationManager alloc] init];
    // Check for iOS 8. Without this guard the code will crash with "unknown selector" on iOS 7.
    if ([locationManager respondsToSelector:@selector(requestWhenInUseAuthorization)]) {

        locationManager.delegate = self;
        locationManager.distanceFilter = kCLDistanceFilterNone;
        locationManager.desiredAccuracy = kCLLocationAccuracyBest;
        [locationManager startUpdatingLocation];
        [locationManager requestWhenInUseAuthorization];
    }

    //Set map options
    self.mapView.showsUserLocation = YES;
    self.mapView.delegate = self;
    self.mapView.scrollEnabled = YES;
    self.mapView.zoomEnabled = YES;
    self.mapView.userTrackingMode = YES;

    // Store the user's location as a Parse PFGeoPoint and call the fetchAffiliatesNearPoint method
    [PFGeoPoint geoPointForCurrentLocationInBackground:^(PFGeoPoint *geoPoint, NSError *error) {
        if (!error) {
            [self fetchAffiliatesNearPoint:geoPoint];
            NSLog(@"Got User Location! %@", geoPoint);
        }
    }];

    /* This is where I am having issues

    for(NSDictionary *affiliates in affiliates) {
        CLLocationCoordinate2D annotationCoordinate = CLLocationCoordinate2DMake([affiliates[@"latitude"] doubleValue], [affiliates[@"longitude"] doubleValue]);

        MapAnnotation *annotation = [[MapAnnotation alloc] init];
        annotation.coordinate = annotationCoordinate;
        annotation.title = affiliates[@"name"];
        annotation.subtitle = affiliates[@"url"];
        [self.mapView addAnnotation:annotation];
    }

*/

}


//Fetch an array of affiliates that are within two miles of the user's current location.
- (void)fetchAffiliatesNearPoint:(PFGeoPoint *)geoPoint
{

    PFQuery *query = [PFQuery queryWithClassName:@"Affiliates"];
    [query whereKey:@"geometry" nearGeoPoint:geoPoint withinMiles:2.0];
    [query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
        if (!error)
        {
            self.affiliates = objects;
            NSLog(@"Nearby Locations %@", _affiliates);
        }
    }];
}


-(void)mapView:(MKMapView *)mapView didUpdateUserLocation:(MKUserLocation *)userLocation
{


    //Zoom map to users current location
    if (!self.initialLocation) {
        self.initialLocation = userLocation.location;
        MKCoordinateRegion mapRegion;
        mapRegion.center = mapView.userLocation.coordinate;
        mapRegion.span.latitudeDelta = .025;
        mapRegion.span.longitudeDelta = .025;

        [mapView setRegion:mapRegion animated: YES];
        }

}
@end

Answer 1

如果要将自定义对象添加到 MapKit map ，您的自定义对象必须符合 MKAnnotation 协议(protocol)。要使您的对象符合协议(protocol)，您只需要实现一个属性:

@property (nonatomic, readonly) CLLocationCoordinate2D coordinate;

其余的属性(例如 title 和 subtitle)和方法是可选的。

您需要做的就是在 PFGeoPoint 上创建一个类别(假设您使用的是 Objective-C)并为 coordinate 属性实现一个 getter。

PFGeoPoint+Annotation.h

@interface PFGeoPoint (Annotation) <MKAnnotation>

@end

PFGeoPoint+Annotation.m

@implementation PFGeoPoint (Annotation)

- (CLLocationCoordinate2D)coordinate {
    return CLLocationCoordinate2DMake(self.latitude, self.longitude);
}

@end

最后，要将其添加到 map ，您将使用:

- (void)addAnnotation:(id <MKAnnotation>)annotation;

例如:[mapView addAnnotation:geoPoint];