writeTransactionWithDefaultRealm:completion:

+ (void)writeTransactionWithDefaultRealm:(void(^)(RLMRealm *realm))block completion:(void (^_Nullable)(void))completion {
    @autoreleasepool {
        RLMRealm *realm = [self openRealm];

        if (realm.inWriteTransaction) {
            safe_block(block, realm);
            return safe_block(completion);
        }

        // Fire any notifications waiting before we start a write tranaction
        [realm refresh];

        NSError *error = nil;

        [realm transactionWithBlock:^{
            safe_block(block, realm);
        } error:&error];

        if (error) {
            NSLog(@"Warning : realm write error : %@", error);
        }

        safe_block(completion);
    }
}