Correct way to declare Global vars

I recently came across a piece of obj-C code that looked something like this:-

#import "LocationSeeker.h"

@interface LocationSeeker ()

@end
NSString *const LocationSeekerMapTypePrefKey= @"LocationSeekerMapTypePrefKey";
NSString *const CenterCoordinateLatitudePrefKey= @"CenterCoordinateLatitudePrefKey";
NSString *const CenterCoordinateLongitudePrefKey= @"CenterCoordinateLongitudePrefKey";

@implementation LocationSeeker

+(void)initialize{//used for making factory settings
    NSLog(@"initializing custom factory settings");
    //THE factory settings are not saved to disk.. These effect at runtime..
    NSMutableDictionary *defaults= [NSMutableDictionary dictionary];
    //Setting the default as Hybrid view for map
     ......
 }

-(IBAction)buttonDidGetPressed:(id)sender{
    NSLog(@"%@",NSStringFromSelector(_cmd));
    NSLog(@"%@",sender);
    
    [[NSUserDefaults standardUserDefaults] setInteger:[sender selectedSegmentIndex] forKey:WhereamiMapTypePrefKey];
    if([sender selectedSegmentIndex]==0){
        [worldView setMapType:MKMapTypeStandard];
    }........
    .....
}

In the code above, there are 3 constants declared at a global level. What i wanted to inquire was whether this is the correct place to declare and define globals. Shouldn't these be declared and defined inside @implementation LocationSeeker ? Like this:

#import "LocationSeeker.h"

@interface LocationSeeker ()

@end
@implementation LocationSeeker
NSString *const LocationSeekerMapTypePrefKey= @"LocationSeekerMapTypePrefKey";
NSString *const CenterCoordinateLatitudePrefKey= @"CenterCoordinateLatitudePrefKey";
NSString *const CenterCoordinateLongitudePrefKey= @"CenterCoordinateLongitudePrefKey";

+(void)initialize{//used for making factory settings
    NSLog(@"initializing custom factory settings");
    //THE factory settings are not saved to disk.. These effect at runtime..
    NSMutableDictionary *defaults= [NSMutableDictionary dictionary];
    //Setting the default as Hybrid view for map
     ......
 }

What are the effects of the difference between the 2 approaches?