注释不会在iOS的MapKit上显示标题/副标题 [英] Annotations dont show title/subtitle on MapKit , iOS
问题描述
我正在解析一些具有某些兴趣点的数据，并尝试使用MapKit框架在地图上显示它们. 我为地图上的对象创建了一个自定义类，称为MyLocation.
I am parsing some data with some points of interests and trying to show them on map using the MapKit framework. I created a custom class for my objects on the map which i call MyLocation.
MyLocation.h:
MyLocation.h:
#import <Foundation/Foundation.h>
#import <MapKit/MapKit.h>
@interface MyLocation : NSObject <MKAnnotation> {
NSString *_name;
NSString *_address;
NSInteger _eventId;
CLLocationCoordinate2D _coordinate;
NSString *title;
NSString *subtitle;
}
@property (nonatomic , copy) NSString *name;
@property (nonatomic , copy) NSString *address;
@property (nonatomic, assign) NSInteger eventId;
@property (nonatomic, readonly) CLLocationCoordinate2D coordinate;
@property (nonatomic, copy) NSString *title;
@property (nonatomic, copy) NSString *subtitle;
- (id)initWithName:(NSString*)name address:(NSString*)address coordinate:(CLLocationCoordinate2D)coordinate;
@end
MyLocation.m:
MyLocation.m:
#import "MyLocation.h"
@implementation MyLocation
@synthesize name = _name;
@synthesize eventId=_eventId;
@synthesize address = _address;
@synthesize coordinate = _coordinate;
@synthesize title;
@synthesize subtitle;
- (id)initWithName:(NSString*)name address:(NSString*)address coordinate:(CLLocationCoordinate2D)coordinate {
if ((self = [super init])) {
_name= [name copy];
_address = [address copy];
_coordinate = coordinate;
}
return self;
}
- (NSString *)title {
if ([_name isKindOfClass:[NSNull class]]) {
NSLog(@"11111111");
return @"Unknown charge";
}
else{
NSLog(@"222222");
return _name;
}
}
- (NSString *)subtitle {
NSLog(@"HAHAHAHAA");
return _address;
}
@end
然后在我的viewController上执行此操作:
Then on my viewController i do this :
//showing on map the points of interests that are stored on "eventList"
int i=0;
for (parsedItem *event in self.eventsList) {
CLLocationCoordinate2D coordinate;
coordinate.latitude = event.latitude;
coordinate.longitude = event.longitude;
if(i==0){
//numbers show map zoom. 500,500 = map stretches 500 meters to the North and the South of current location
MKCoordinateRegion region =
MKCoordinateRegionMakeWithDistance (coordinate,1000,1000);
[mapView setRegion:region animated:NO];
}
MyLocation *eventAnnotation = [[MyLocation alloc] initWithName:event.typeEvent address:event.titleEvent coordinate:coordinate] ;
eventAnnotation.name = event.typeEvent;
eventAnnotation.address = event.titleEvent;
eventAnnotation.eventId = i;
i++;
[mapView addAnnotation:eventAnnotation];
}
后来，我使用更多代码将图像提供给注释，如果我单击注释，则所有内容都会显示在地图上，但我看不到带有标题和副标题的窗口.我只看到注释，但没有单击它们时应获得的额外信息.
Later i use some more code to give images to the annotations and everything appears on the map BUT if i click on the annotations i dont see the window with the title and the subtitle. I only see the annotations but without the extra information that i should get when i click on them.
我想这行代码有问题:
MyLocation *eventAnnotation = [[MyLocation alloc] initWithName:event.typeEvent address:event.titleEvent coordinate:coordinate] ;
有什么想法吗?
请补充一点，我也使用此功能:
just to add that i also use this function:
- (MKAnnotationView *)mapView:(MKMapView *)mapView2 viewForAnnotation:(id <MKAnnotation>)annotation {
static NSString *identifier = @"MyLocation";
if ([annotation isKindOfClass:[MyLocation class]]) {
NSLog(@"I got into the class!!!");
MKPinAnnotationView *annotationView = (MKPinAnnotationView *) [mapView dequeueReusableAnnotationViewWithIdentifier:identifier];
if (annotationView == nil) {
annotationView = [[MKPinAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:identifier];
} else {
annotationView.annotation = annotation;
}
annotationView.enabled = YES;
annotationView.canShowCallout = YES;
MyLocation *eventAnnotation=annotation;
if ([eventAnnotation.address isEqualToString: @"Culture_07/02/2012"]) {
NSLog(@"Mphkeeee");
annotationView.image=[UIImage imageNamed:@"culture.png"];
//annotation.title = @"Holla!";
} else if ([eventAnnotation.address isEqualToString: @"Sports_06/29/2012"]) {
annotationView.image=[UIImage imageNamed:@"sports.png"];
} else if ([eventAnnotation.address isEqualToString: @"Accident_06/29/2012"]) {
annotationView.image=[UIImage imageNamed:@"accident.png"];
} else if ([eventAnnotation.address isEqualToString: @"Problem_06/29/2012"]) {
annotationView.image=[UIImage imageNamed:@"problem.png"];
} else if ([eventAnnotation.address isEqualToString: @"Traffic_07/02/2012"]) {
annotationView.image=[UIImage imageNamed:@"traffic.png"];
} else if ([eventAnnotation.address isEqualToString: @"Music_06/29/2012"]) {
annotationView.image=[UIImage imageNamed:@"music.png"];
}
return annotationView;
}
return nil;
}
推荐答案
在地图视图中为title和subtitle使用自定义getter方法而不是显式设置这些属性是可以的.
Using a custom getter method for the title and subtitle instead of setting those properties explicitly is fine with the map view.
未显示标注的原因是title(正在返回_name-设置为event.typeEvent)正在返回nil或空字符串.
The reason your callouts are not showing is because title (which is returning _name -- which is set to event.typeEvent) is returning a nil or empty string.
您的getter方法正在检查_name是否为NSNull类型，但它可能是NSString，仍然是nil或空字符串.
Your getter method is checking if _name is of type NSNull but it could be an NSString and still be nil or an empty string.
当title为nil或为空字符串时，注释将不会显示标注(即使canShowCallout设置为YES，即使subtitle返回非空值)也是如此.
When title is nil or an empty string, the annotation will not display the callout (even if canShowCallout is set to YES and even if subtitle is returning a non-empty value).
因此，typeEvent最有可能是nil或空字符串.
So it's most likely that typeEvent is nil or an empty string.
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