ios - 如何创建符合 协议(protocol)的自定义类

Question

我有一张显示所有餐厅对象的 map 。我正在尝试将餐厅对象传递给 map 注释，以便我可以显示包含所有餐厅信息的详细 View 。经过研究，我试图创建一个符合协议(protocol)的类，但是我无法在 map 中放置注释。这是我的代码:

RestaurantAnnotationClass.h(自定义类):

#import <Foundation/Foundation.h>
#import <MapKit/MapKit.h>
#import "Restaurant.h"

static NSString *restaurantAnnotationIdentifier = @"restaurantAnnotationIdentifier";

@interface RestaurantAnnotation : NSObject <MKAnnotation>

@property (copy, nonatomic) NSString *title;
@property (copy, nonatomic) NSString *subtitle;
@property (nonatomic) CLLocationCoordinate2D coordinate;
@property (nonatomic, strong) Restaurant *restaurant;


- (id)initWithTitle:(NSString *)newTitle subtitle:(NSString *)newSubtitle restaurant:(Restaurant *)newRestaurant location:(CLLocationCoordinate2D)location;

- (MKAnnotationView *)annotationView;

@end

RestaurantAnnotationClass.m

    #import "RestaurantAnnotation.h"

@implementation RestaurantAnnotation



- (id)initWithTitle:(NSString *)newTitle subtitle:(NSString *)newSubtitle restaurant:(Restaurant *)newRestaurant location:(CLLocationCoordinate2D)location {

    self = [super init];
    if (self) {
        self.title = newTitle;
        self.coordinate = location;
        self.subtitle = newSubtitle;
        self.restaurant = newRestaurant; 
    }

    return self;
}

- (MKAnnotationView *)annotationView {

    MKAnnotationView *annotationView = [[MKAnnotationView alloc] initWithAnnotation:self reuseIdentifier:restaurantAnnotationIdentifier];
    annotationView.enabled = YES;
    annotationView.canShowCallout = YES;
    annotationView.rightCalloutAccessoryView = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];

    return annotationView;

}

@end

我的 map Controller

- (NSArray *)convertRestaurantToMKAnnotationsFromArray:(NSArray *)restaurantsArray {
    NSMutableArray *mkPointAnnotations = [NSMutableArray new];

    double mileToMeters = 1609.344;
    CLLocation *userLocation = [[CLLocation alloc] initWithLatitude:self.userCurrentLocation.coordinate.latitude longitude:self.userCurrentLocation.coordinate.longitude];
    for (Restaurant *restaurant in restaurantsArray) {
        CLLocation *restaurantLocation = [[CLLocation alloc] initWithLatitude:restaurant.geoLocation.latitude longitude:restaurant.geoLocation.longitude];

       RestaurantAnnotation *newRestaurantAnnotation = [[RestaurantAnnotation alloc] initWithTitle:restaurant.name subtitle:[NSString stringWithFormat:@"%.02f",[userLocation distanceFromLocation:restaurantLocation] / mileToMeters] restaurant:restaurant location:CLLocationCoordinate2DMake(restaurant.geoLocation.latitude, restaurant.geoLocation.longitude)];

        [mkPointAnnotations addObject: newRestaurantAnnotation];

    }
    return mkPointAnnotations;
}

我在这里实现了 vuewforannotation 方法

- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation {


    if ([annotation isKindOfClass:[MKUserLocation class]])
        return nil;

    if ([annotation isKindOfClass:[RestaurantAnnotation class]]) {
        RestaurantAnnotation *restaurant = (RestaurantAnnotation *)annotation;
        MKAnnotationView *restaurantAnnotationView = [mapView dequeueReusableAnnotationViewWithIdentifier:restaurantAnnotationIdentifier];

        if (restaurantAnnotationView == nil)
            restaurantAnnotationView = restaurant.annotationView;
        else
            restaurantAnnotationView.annotation = annotation;

        return restaurantAnnotationView;
    } else
        return nil;

}

提前谢谢你

Answer 1

我在应用 viewForAnnotation 方法时犯了一个错误，现在这是我的代码

- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation {

if ([annotation isKindOfClass:[MKUserLocation class]]) {
    return nil;
}

if ([annotation isKindOfClass:[RestaurantAnnotation class]]) {
    RestaurantAnnotation *restauntAnnotation = (RestaurantAnnotation *)annotation;
    MKAnnotationView *restaurantAnnotationView = [mapView dequeueReusableAnnotationViewWithIdentifier:restaurantAnnotationIdentifier];
    if (restaurantAnnotationView == nil) {
        restaurantAnnotationView = restauntAnnotation.annotationView;
    } else {
        restaurantAnnotationView.annotation = annotation;
        return restaurantAnnotationView;
    }
}
return nil;