Ios 目标C：CoreData和MapKit

我在coredata中有经度和纬度类型Double。叫艾德曼。我为singleton创建类usersIndex

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

//OutgoingUser
@interface usersIndex : NSObject

//@property (nonatomic) AddMan* user;

@property (nonatomic, retain) NSNumber *longtitude;
@property (nonatomic, retain) NSNumber *latitude;

+ (usersIndex *)sharedManager;
+ (void) del;

@end

我创建了ViewController和钩住的MapKit。在我的课堂上，我需要显示coredata中的所有标记。我如何实现这一点？ 我有一个版本的如何做到这一点，但我不太明白它

for (int i = 0; i <_users.count; i ++) {
     _index = i;
    
     CustomMKPointAnnotation * myAnnot = [[CustomMKPointAnnotation alloc] init];
     NSManagedObject * obj = [_users objectAtIndex: _index];
     theCoordinate.latitude = [[obj valueForKey: @ "lantitude"] doubleValue];
     theCoordinate.longitude = [[obj valueForKey: @ "longitude"] doubleValue];
     myAnnot.coordinate = theCoordinate;
     myAnnot.indexAnnotation = i;
     myAnnot.title = [NSString stringWithFormat: @ "% @", [obj valueForKey: @ "name"]];
     myAnnot.subtitle = [NSString stringWithFormat: @ "% @", [obj valueForKey: @ "lastname"]];
    
     [Self.totalMapView addAnnotation: myAnnot];
}

for（int i=0；i
for (int i = 0; i <_users.count; i ++) {
     _index = i;
    
     CustomMKPointAnnotation * myAnnot = [[CustomMKPointAnnotation alloc] init];
     NSManagedObject * obj = [_users objectAtIndex: _index];
     theCoordinate.latitude = [[obj valueForKey: @ "lantitude"] doubleValue];
     theCoordinate.longitude = [[obj valueForKey: @ "longitude"] doubleValue];
     myAnnot.coordinate = theCoordinate;
     myAnnot.indexAnnotation = i;
     myAnnot.title = [NSString stringWithFormat: @ "% @", [obj valueForKey: @ "name"]];
     myAnnot.subtitle = [NSString stringWithFormat: @ "% @", [obj valueForKey: @ "lastname"]];
    
     [Self.totalMapView addAnnotation: myAnnot];
}