Difference between unwind segue and delegation
delegates, ios, objective-c, uistoryboardsegue, xcode
Solution
Using an unwind segue is very similar to having a delegate, with the following advantages:
- You don't need to implement any dismiss logic
- You don't need to pass references up and down the navigation stack
- You don't need to declare a delegate protocol
- It's trivial to unwind back a number of stages in your app
The disadvantages are
- Dependent on using storyboards (which may hamper reusability)
- If there are a lot of them, it can lead to the same messiness as you can get in `prepareForSegue` with a lot of branching off identifier names
- If you decide to present the view controller via some other method (not a segue) then you can't unwind back from it
The code you have looks good. I'd stick with it.
Problem
I wonder if anybody can explain the difference between using a unwind segue and using delegation in the example I have below: I have a `FriendsTableViewController` populated by an `array` of friends and another `AddFriendTableViewController` with a function to add a `friend` to the `FriendsTableViewController`. This is how I send the data from my `AddFriendViewController` with a `unwind segue`: ``` #pragma mark - Navigation // In a storyboard-based application, you will often want to do a little preparation before navigation - (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender { // Check whether the Done button was tapped. // If it wasn’t, instead of saving the friend, the method returns without doing anything else. if (sender != self.doneButton) return; // See whether there’s text in the text field. if (self.nameTextField.text.length > 0) { // If there’s text, create a new friend and give it's properties the input from the text fields. self.friend = [[Friend alloc] initWithName:self.nameTextField.text dateOfBirth:self.birthdayDatePicker.date numberOfGifts:0]; } } ``` This is how I add the data from the `AddFriendTableViewController` to the `array` in `FriendsTableViewController` with the `unwind segue action`: ``` #pragma mark - Actions - (IBAction)unwindSegue:(UIStoryboardSegue *)segue { // Retrieve the source view controller, the controller that is unwinding from. AddFriendTableViewController *soruce = [segue sourceViewController]; // Retrieve the soruce view controller’s friend object. Friend *friend = soruce.friend; // See whether the item exists. // If it’s nil, either the Cancel button closed the screen or the text field had no text, so you don’t want to save the item. if (friend != nil) { // If it does exist, add the item to the friends array. [self.friends addObject:friend]; // Reload the data in the table. [self.tableView reloadData]; } } ``` Now this works as I want so I hope I'm not breaking any stackoverflow rules or offending anyone, but I just wanted to know what is the difference between the way my example code is used and if the same scenario was made but with custom delegate methods for the `AddFriendViewController`. If some can explain it would be great!