Clear complete Realm Database

RealmSwift: Simple reset using a flag

Tried the above answers, but posting one more simple way to delete the realm file instead of migrating:

Realm.Configuration.defaultConfiguration.deleteRealmIfMigrationNeeded = true

This simply sets a flag so that Realm can delete the existing file rather than crash on try! Realm()

Instead of manually deleting the file

Thought that was simpler than the Swift version of the answer above:

guard let path = Realm.Configuration.defaultConfiguration.fileURL?.absoluteString else {
    fatalError("no realm path")
}

do {
    try NSFileManager().removeItemAtPath(path)
} catch {
    fatalError("couldn't remove at path")
}

Update:

Since posting, a new method has been added to delete all objects (as jpsim has already mentioned):

// Obj-C
[realm beginWriteTransaction];
[realm deleteAllObjects];
[realm commitWriteTransaction];


// Swift
try! realm.write {
  realm.deleteAll()
}

Note that these methods will not alter the data structure; they only delete the existing records. If you are looking to alter the realm model properties without writing a migration (i.e., as you might do in development) the old solution below may still be useful.

Original Answer:

You could simply delete the realm file itself, as they do in their sample code for storing a REST response:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    //...

    // Ensure we start with an empty database
    [[NSFileManager defaultManager] removeItemAtPath:[RLMRealm defaultRealmPath] error:nil];

    //...
}

---

Update regarding your comment:

If you need to be sure that the realm database is no longer in use, you could put realm's notifications to use. If you were to increment an openWrites counter before each write, then you could run a block when each write completes:

self.notificationToken = [realm addNotificationBlock:^(NSString *notification, RLMRealm * realm) {
    if([notification isEqualToString:RLMRealmDidChangeNotification]) {
        self.openWrites = self.openWrites - 1;

        if(!self.openWrites && self.isUserLoggedOut) {
            [[NSFileManager defaultManager] removeItemAtPath:[RLMRealm defaultRealmPath] error:nil];
        }
    }
}];