Change PersistentContainer URL dynamically.

AppDelegate.h

#import <UIKit/UIKit.h>
#import <CoreData/CoreData.h>

@interface AppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;

@property (readonly, strong) NSPersistentContainer *persistentContainer;
@property (nonatomic) NSURL *databaseURL;

- (void)saveContext;

@end

AppDelegate.m

#import "AppDelegate.h"

@implementation AppDelegate

#pragma mark - Core Data stack

@synthesize persistentContainer = _persistentContainer;

- (NSPersistentContainer *)persistentContainer {
    @synchronized (self) {
        if (_persistentContainer == nil) {
            _persistentContainer = [[NSPersistentContainer alloc] initWithName:@"AppName"];
            if (self.databaseURL) {
                NSPersistentStoreDescription *storeDescription = _persistentContainer.persistentStoreDescriptions.firstObject;
                storeDescription.URL = self.databaseURL;
            }
            [_persistentContainer loadPersistentStoresWithCompletionHandler:^(NSPersistentStoreDescription *storeDescription, NSError *error) {
                if (error != nil) {
                    NSLog(@"Unresolved error %@, %@", error, error.userInfo);
                    abort();
                }
            }];
        }
    }
    
    return _persistentContainer;
}

- (void)setDatabaseURL:(NSURL *)databaseURL
{
    _databaseURL = databaseURL;
    _persistentContainer = nil;
}

#pragma mark - Core Data Saving support

- (void)saveContext {
    NSManagedObjectContext *context = self.persistentContainer.viewContext;
    NSError *error = nil;
    if ([context hasChanges] && ![context save:&error]) {
        NSLog(@"Unresolved error %@, %@", error, error.userInfo);
        abort();
    }
}

@end