Use an IBOutletCollection to hold a reference to all of your textfields instead of individual IBOutlets. This works the same way as connecting IBOutlets.
Declare a property like so
@property (nonatomic, strong) IBOutletCollection(UITextField) NSArray *textFields;
Then iterate through all the textfields and set whatever properties you want.
for (UITextField *textField in self.textFields) {
textField.inputAccessoryView = numberToolbar;
}