ios - 为注释添加标题

Question

我有这段代码可以在带有自定义图像的 map 上显示 4 个点。我已经开始了解到，也许我构建它的方式不是最佳的，但它就是我所拥有的。

请帮助我学习如何让我创建的标题在有人点击时显示在 map 上并带有自定义 poi。

我有两个与 View 一起工作的类。这些类是 MapAnnotation 和 LocationsViewController。

这是每个的代码。

MapAnnotation.h

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
#import <MapKit/MapKit.h>

@interface MapAnnotation : NSObject <MKAnnotation, MKMapViewDelegate> 
{
    CLLocationCoordinate2D _coordinate;
    NSString * title;

}

@property (nonatomic, copy) NSString *title;
- (id)initWithCoordinate:(CLLocationCoordinate2D)coordinate;

@end

MapAnnotation.m

#import "MapAnnotation.h"
#import "LocationsViewController.h"

@implementation MapAnnotation

@synthesize coordinate = _coordinate;
@synthesize title;

- (id)initWithCoordinate:(CLLocationCoordinate2D)coordinate
{
    self = [super init];

    if (self != nil)
    {
        _coordinate = coordinate;
    }

    return self;
}

@end

LocationsViewController.h

#import "TechBookAppDelegate.h"
#import <UIKit/UIKit.h>
#import <MapKit/MapKit.h>

@interface LocationsViewController : UIViewController <MKMapViewDelegate, MKAnnotation>
{
    IBOutlet MKMapView *worldView;
    IBOutlet UIActivityIndicatorView *activityIndicator;

}

- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id < MKAnnotation >)annotation;
@end

LocationsViewController.m

#import "LocationsViewController.h"
#import "MapAnnotation.h"
@interface LocationsViewController ()
@end

@implementation LocationsViewController

@synthesize coordinate = _coordinate;
@synthesize title;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Initialization code
    }
    return self;
}

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

    static NSString *AnnotationViewID = @"annotationViewID";

    MKAnnotationView *annotationView = (MKAnnotationView *)[mapView dequeueReusableAnnotationViewWithIdentifier:AnnotationViewID];

    if (annotationView == nil)
    {
        annotationView = [[MKAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:AnnotationViewID];
    }

    annotationView.image = [UIImage imageNamed:@"app_icon_sm.png"];
    annotationView.annotation = annotation;

    return annotationView;
}



- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    worldView.showsUserLocation = NO;

    CLLocationCoordinate2D wisconsin = {.latitude =  45.620775, .longitude =  -89.47844};
    CLLocationCoordinate2D pennsyvainia = {.latitude =  39.912417, .longitude =  -77.663268};
    CLLocationCoordinate2D nevada = {.latitude =  36.054362, .longitude =  -115.020470};
    CLLocationCoordinate2D texas = {.latitude =  32.555038, .longitude =  -94.295592};
    MapAnnotation *pinWI = [[MapAnnotation alloc] initWithCoordinate: wisconsin] ;
    MapAnnotation *pinPA = [[MapAnnotation alloc] initWithCoordinate: pennsyvainia];
    MapAnnotation *pinNV = [[MapAnnotation alloc] initWithCoordinate: nevada];
    MapAnnotation *pinTX = [[MapAnnotation alloc] initWithCoordinate: texas];
    //UIImage *star = [UIImage imageNamed:@"locations_marker.png"];
                        //////////////////
    pinWI.title = @"Rhinelander, WI";///////
    pinPA.title = @"Chambersburg, PA";//////I dont understand why these do not output a
    pinNV.title = @"Henderson, NV";/////////title if the title property is a part of the
    pinTX.title = @"Marshall, TX";////////// MKAnnotation
                        //////////////////
    [worldView addAnnotation:pinTX];
    [worldView addAnnotation:pinNV];
    [worldView addAnnotation:pinWI];
    [worldView addAnnotation:pinPA];

}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
@end

我想我需要一个函数来创建标题？我真的希望我不必创建更多类来执行此操作。

Answer 1

您的主要问题是:

How to make the titles I created show up on the map with the custom poi when someone taps it.

在viewForAnnotation委托(delegate)方法中，需要将注解 View 的canShowCallout属性设置为YES(默认为NO):

if (annotationView == nil)
{
    annotationView = [[MKAnnotationView alloc] initWithAnnotation...
    annotationView.canShowCallout = YES;  // <-- add this line
}

一些与问题无关的附加评论:

1. 在 MapAnnotation.h 中，此类将仅实现 MKAnnotation，而不是 MKMapViewDelegate，因此将其从协议(protocol)列表中删除以避免潜在的编译器警告并使代码更清晰:

   @interface MapAnnotation : NSObject <MKAnnotation>
   

2. 在 MapAnnotation.m 中，您不需要 #import "LocationsViewController.h"。将其删除。

3. 在 LocationsViewController.h 中，此类将不会实现MKAnnotation，因此将其从协议(protocol)列表中删除以避免潜在的编译器警告并使代码更清晰和清洁工:

   @interface LocationsViewController : UIViewController <MKMapViewDelegate>
   

4. 此外，在 LocationsViewController.h 中，无需声明您将要实现的委托(delegate)方法。您可以删除 viewForAnnotation 声明。

5. 在 LocationsViewController.m 中，coordinate 和 title 的 @synthesize 不属于此处。删除它们。