如何实现在Objective-C MKClusterAnnotations？

Question

我努力使集群的意见对于那些真正接近对方对我的苹果地图的注解。我知道苹果已经本土集群视图工具包出来与iOS 11，但所有的教程我能在网上找到的都写在斯威夫特。我希望有人能教我或我推荐，我能读，找出如何实现在Objective-C集群注释任何教程。

我的想法是创建一个安装ClusterView类，它继承了MKAnnotationView类，然后在MapView的控制器创建了ClusterView的实例。

我已阅读来自苹果，它只是提供了我可能需要调用函数的文档，但它并没有解释如何使用他们，这是链接到苹果文档：https://developer.apple.com/documentation/mapkit/mkclusterannotation?language=objc

任何帮助，将不胜感激！

Answer 1

以下是基本步骤：

1. 定义你的注解视图，指定clusteringIdentifier和collisionMode：

   //  CustomAnnotationView.h
   
   @import MapKit;
   
   @interface CustomAnnotationView : MKMarkerAnnotationView
   
   @end

   和

   //  CustomAnnotationView.m
   
   #import "CustomAnnotationView.h"
   
   static NSString *identifier = @"com.domain.clusteringIdentifier";
   
   @implementation CustomAnnotationView
   
   - (instancetype)initWithAnnotation:(id<MKAnnotation>)annotation reuseIdentifier:(NSString *)reuseIdentifier {
       if ((self = [super initWithAnnotation:annotation reuseIdentifier:reuseIdentifier])) {
           self.clusteringIdentifier = identifier;
           self.collisionMode = MKAnnotationViewCollisionModeCircle;
       }
   
       return self;
   }
   
   - (void)setAnnotation:(id<MKAnnotation>)annotation {
       [super setAnnotation:annotation];
   
       self.clusteringIdentifier = identifier;
   }
   
   @end

2. 或者，如果你愿意，你可以定义自己的集群标注视图，指定displayPriority和collisionMode。这其中还更新图像群集说明有多少注解集群：

   //  ClusterAnnotationView.h
   
   @import MapKit;
   
   @interface ClusterAnnotationView : MKAnnotationView
   
   @end

   和

   //  ClusterAnnotationView.m
   
   #import "ClusterAnnotationView.h"
   
   @implementation ClusterAnnotationView
   
   - (instancetype)initWithAnnotation:(id<MKAnnotation>)annotation reuseIdentifier:(NSString *)reuseIdentifier {
       if ((self = [super initWithAnnotation:annotation reuseIdentifier:reuseIdentifier])) {
           self.displayPriority = MKFeatureDisplayPriorityDefaultHigh;
           self.collisionMode = MKAnnotationViewCollisionModeCircle;
       }
   
       return self;
   }
   
   - (void)setAnnotation:(id<MKAnnotation>)annotation {
       super.annotation = annotation;
       [self updateImage:annotation];
   }
   
   - (void)updateImage:(MKClusterAnnotation *)cluster {
       if (!cluster) {
           self.image = nil;
           return;
       }
   
       CGRect rect = CGRectMake(0, 0, 40, 40);
       UIGraphicsImageRenderer *renderer = [[UIGraphicsImageRenderer alloc] initWithSize:rect.size];
       self.image = [renderer imageWithActions:^(UIGraphicsImageRendererContext * _Nonnull rendererContext) {
           // circle
   
           [[UIColor blueColor] setFill];
           [[UIColor whiteColor] setStroke];
   
           UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:rect];
           path.lineWidth = 0.5;
           [path fill];
           [path stroke];
   
           // count
   
           NSString *text = [NSString stringWithFormat:@"%ld", (long) cluster.memberAnnotations.count];
           NSDictionary<NSAttributedStringKey, id> *attributes = @{
               NSFontAttributeName: [UIFont preferredFontForTextStyle: UIFontTextStyleBody],
               NSForegroundColorAttributeName: [UIColor whiteColor]
                                                                   };
           CGSize size = [text sizeWithAttributes:attributes];
           CGRect textRect = CGRectMake(rect.origin.x + (rect.size.width  - size.width)  / 2,
                                        rect.origin.y + (rect.size.height - size.height) / 2,
                                        size.width,
                                        size.height);
           [text drawInRect:textRect withAttributes:attributes];
       }];
   }
   
   @end

   您不必创建自己的子类集群，如果你不想。但是，这只是说明了如何可以完全控制集群的出现，你应该选择这样做。
3. 那么你的视图控制器只需要注册适当的类，你就大功告成了（没有地图视图代表需要）： [self.mapView registerClass:[CustomAnnotationView class] forAnnotationViewWithReuseIdentifier:MKMapViewDefaultAnnotationViewReuseIdentifier]; 如果你想使用自定义聚类图，你可以注册，太： [self.mapView registerClass:[ClusterAnnotationView class] forAnnotationViewWithReuseIdentifier:MKMapViewDefaultClusterAnnotationViewReuseIdentifier]; 例如：

   //  ViewController.m
   
   #import “ViewController.h"
   
   @import MapKit;
   
   #import "CustomAnnotationView.h"
   #import "ClusterAnnotationView.h"
   
   @interface ViewController ()
   @property (weak, nonatomic) IBOutlet MKMapView *mapView;
   @end
   
   @implementation ViewController
   
   - (void)viewDidLoad {
       [super viewDidLoad];
   
       [self configureMapView];
   }
   
   - (void)configureMapView {
       self.mapView.userTrackingMode = MKUserTrackingModeFollow;
   
       [self.mapView registerClass:[CustomAnnotationView class] forAnnotationViewWithReuseIdentifier:MKMapViewDefaultAnnotationViewReuseIdentifier];
       [self.mapView registerClass:[ClusterAnnotationView class] forAnnotationViewWithReuseIdentifier:MKMapViewDefaultClusterAnnotationViewReuseIdentifier];
   }
   
   // I’m going to search for restaurants and add annotations for those,
   // but do whatever you want
   
   - (void)performSearch {
       MKLocalSearchRequest *request = [[MKLocalSearchRequest alloc] init];
       request.naturalLanguageQuery = @"restaurant";
       request.region = self.mapView.region;
   
       MKLocalSearch *search = [[MKLocalSearch alloc] initWithRequest:request];
       [search startWithCompletionHandler:^(MKLocalSearchResponse * _Nullable response, NSError * _Nullable error) {
           if (error) {
               NSLog(@"%@", error);
               return;
           }
   
           for (MKMapItem *mapItem in response.mapItems) {
               MKPointAnnotation *annotation = [[MKPointAnnotation alloc] init];
               annotation.coordinate = mapItem.placemark.coordinate;
               annotation.title = mapItem.name;
               annotation.subtitle = mapItem.placemark.thoroughfare;
               [self.mapView addAnnotation:annotation];
           }
       }];
   }
   
   @end

这产生了：

Answer 2

这是一个基本的例子是几个步骤一样简单

1）添加以下注释中viewDidLoad会工作得很好

MKPointAnnotation *point1 = [[MKPointAnnotation alloc] init];
CLLocationCoordinate2D c1;
c1.latitude = 46.469391;
c1.longitude = 30.740883;
point1.coordinate = c1;
point1.title = @"Minsk, Belarus";
[self.mapView addAnnotation:point1];

MKPointAnnotation *point2 = [[MKPointAnnotation alloc] init];
CLLocationCoordinate2D c2;
c2.latitude = 46.469391;
c2.longitude = 30.740883;
point2.coordinate = c2;
point2.title = @"Odessa, Ukraine";
[self.mapView addAnnotation:point2];

2）在MapView类：MKMapViewDelegate的viewForAnnotation注解提供可重用的视图，如下所示：

- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>)annotation {
    if ([annotation isKindOfClass:[MKPointAnnotation class]]) {

        MKMarkerAnnotationView* annotationView = (MKMarkerAnnotationView *) (MKMarkerAnnotationView *)[_mapView dequeueReusableAnnotationViewWithIdentifier:@"Jacky.S"];
        if (annotationView == nil) {
            annotationView = [[MKMarkerAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:@"Jacky.S"];
            annotationView.enabled = YES;
            annotationView.clusteringIdentifier = @"pins";
            // annotationView.glyphImage = [UIImage imageNamed:@"we can use a nice image instead of the default pins"];
        } else {
            annotationView.annotation = annotation;
            annotationView.clusteringIdentifier = @"pins";
        }
        return annotationView;
    }
    return nil;
}

不要忘记设置MKMapViewDelegate到UIViewController

[self.mapView setDelegate:self];

刚刚更新完张贴gist显示如何继承MKMarkerAnnotationView