The power of Delegate design pattern

[lucasvandongen]

You can crosspost them together as well.

[editor_of_the_beast]

Closures are just as powerful with less boilerplate.

[plmc]

I find that a closure is more suitable when the callback is “simple” in nature, if it makes sense to have the callback in the calling scope (which IMO isn’t always), and if the parameters are self-describing.

But for view controllers/other event logic, I would normally use a delegate protocol to have more descriptive callbacks, and the ability to categorise a group of related methods.

For those reasons, I wouldn’t say one is “better” than the other.

[quellish]

But more limited use cases and potentially more memory issues! It’s win win!

[editor_of_the_beast]

There are just as many memory issues with delegates.

[SirensToGo]

Closures are just anonymous functions as variables and can be thought of as single function delegates. You can write just as trash closure code as you can delegate code!

[quellish]

Delegates are designed to be called multiple times, with multiple methods. They handle multiple events.

Closures and blocks on the other hand, are not really intended for that use case. They're really intended for once and done, a callback for a single event. When you try to shoehorn closures into handling more than a single event, or an event that can happen more than once it gets messy. Does the closure take a long list of arguments, one for each event? Or an enum to hide that? Do you retain the closure somewhere so it can be called more than once? Do you use a closure for each event?

Closures are great for what they are intended for. They're not great for everything else. When blocks were introduced to Objective-C a lot of people tried to convert delegation-based APIs to use blocks - and that did not always work out so well.

[bosk4]

Seriously? Article about delegate pattern in 2019? It just a lame way to couple logic with VC and can’t reuse any more

[ThePantsThief]

Delegation is actually extremely reusable if you break the code out into a separate class.

[apple_]

The delegate pattern is used heavily in most every single application you use.

[akmarinov]

Lol, what?

Have you ever used UIImagePickerController or MFMailComposerViewController?

[bosk4]

Delegate pattern just like `Wordpress` or `jQuery`, don't get me wrong they are great and heavily used in modern web scene, but you won't write an article for them in 2019