注释不能拖 [英] Annotation not dragging

问题描述

MapPin.h：

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

@interface MapPin : NSObject<MKAnnotation> {
CLLocationCoordinate2D coordinate;
NSString *title;
NSString *subtitle;
}
@property (nonatomic,readwrite,assign)CLLocationCoordinate2D coordinate;
- (id)initWithCoordinates:(CLLocationCoordinate2D)location placeName:(NSString  *)placeName description:(NSString *)description;
-(void)setCoordinate:(CLLocationCoordinate2D)newCoordinate;
@end

和这里的MapPin.m

and here's the MapPin.m

#import "MapPin.h"

@implementation MapPin
@synthesize coordinate;

-(NSString *)subtitle{
return nil;
}
-(NSString *)title{
     return nil;
    }
-(id)initWithCoordinates:(CLLocationCoordinate2D)location placeName:(NSString *)placeName description:(NSString *)description{
    coordinate=location;
    return self;

}
-(CLLocationCoordinate2D)location{
    return coordinate;
}
-(void)setCoordinate:(CLLocationCoordinate2D)newCoordinate{
     coordinate=newCoordinate;
}

@end

在ViewController.h我已经通过了MKMapViewDelegate协议。
和这里的ViewController.m：

In the ViewController.h i've adopted the MKMapViewDelegate protocol. and here's the ViewController.m :

-(MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation{
    MKPinAnnotationView *pin = (MKPinAnnotationView *)[self.MyMap dequeueReusableAnnotationViewWithIdentifier:@"myPin"];
    if(pin == nil){
        pin=[[MKPinAnnotationView alloc]initWithAnnotation:annotation reuseIdentifier:@"myPin"];

    }
     else{
        pin.annotation=annotation;
    }
    pin.draggable=YES;
return  pin;
}
//Add Location button
 - (IBAction)AddPin:(id)sender {
    CLLocationCoordinate2D center;
    center.latitude=Locate.location.coordinate.latitude;
    center.longitude=Locate.location.coordinate.longitude;
    MKCoordinateRegion region;
    region.center=center;
    region.span.latitudeDelta=0.2f;
    region.span.longitudeDelta=0.2f;
    MapPin *myPin = [[MapPin alloc]initWithCoordinates:self.MyMap.centerCoordinate placeName:@"LoMinder!" description:@"Set Location for LoMinder!"];
    [_MyMap addAnnotation:myPin];
 }
 //Dropping the pin:
    - (void)mapView:(MKMapView *)mapView
 annotationView:(MKAnnotationView *)annotationView
 didChangeDragState:(MKAnnotationViewDragState)newState
   fromOldState:(MKAnnotationViewDragState)oldState
{
    //Region
    MKCoordinateRegion myRegion;
    //Center
    CLLocationCoordinate2D center;
    if (newState == MKAnnotationViewDragStateStarting)
    {
         [_MyMap setRegion:myRegion animated:YES];
    }
    if(newState == MKAnnotationViewDragStateDragging)
    {
        myRegion.center=annotationView.annotation.coordinate;
        myRegion.span.latitudeDelta=0.2f;
        myRegion.span.longitudeDelta=0.2f;
        [_MyMap setRegion:myRegion animated:YES];
    }
    if(newState==MKAnnotationViewDragStateEnding)
    {
        arrived=self.MyMap.centerCoordinate;
        center=annotationView.annotation.coordinate;
        myRegion.center=center;
        myRegion.span.latitudeDelta=0.2f;
        myRegion.span.longitudeDelta=0.2f;
        [_MyMap setRegion:myRegion animated:YES];
     }
  }

/////
我还导入了MapPin.h到的ViewController。
当我运行我的应用程序，我应该preSS的添加位置按钮ORD ER拿到注释针，我preSS按钮，注释销出现在地图上，但问题是，当我尝试拖动它，它似乎是取消拖动。
请人一些帮助。
谢谢：）

///// I've also imported the MapPin.h into the ViewController. When I run my app, I should press the Add Location button in ord er to get the annotation pin, I press the button, the annotation pin appears on the map, but the problem is that when i try to drag it, it seems to be un-draggable. Please people some help. Thank you :)

推荐答案

由MapPin.m更改标题的方法解决
让它返回任何东西，但无所获。

Solved by changing the title method in the MapPin.m Make it return anything but nil.

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