Swift version: 5.6
Delegates are extremely common in iOS development, but fortunately they are easy to understand: a delegate is any object that should be notified when something interesting has happened. What that "something interesting" means depends on the context: for example, a table view's delegate gets notified when the user taps on a row, whereas a navigation controller's delegate gets notified when the user moves between view controllers.
When you agree to be the delegate for an object, you will almost certainly need to conform to a specific protocol, such as UITableViewDelegate
. These protocols will usually have some optional methods that you can implement if you care when something happens, for example, table views can notify you when users deselect a row, but most developers don't care. These protocols may also have some required methods that you must implement.
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This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.
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