How to add 2 buttons into the UINavigationbar on the right side without IB?

You don´t have to add two buttons. You just need to add

UIBarButtonSystemItemFlexibleSpace 

not

UIBarButtonSystemItemFixedSpace

and a button, so that it will be on right side.

Like this:

UIToolbar *toolbar = [[UIToolbar alloc] initWithFrame:CGRectMake(0, 0, 320, 40)];
toolbar.barStyle = UIBarStyleBlackTranslucent;

UIBarButtonItem *spaceButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];

UIBarButtonItem *infoButtonItem1 = [[UIBarButtonItem alloc] initWithTitle:@"Done" style:UIBarButtonItemStyleDone target:self action:@selector(empresaTextFieldDone)];    

toolbar.items = [NSArray arrayWithObjects: spaceButton, infoButtonItem1, nil];