Delegated is a super small package that helps you avoid retain cycles when using closure-based delegation.
New Medium post here.
Original Medium post (Delegated 0.1.2) here.
🚨 WARNING! Delegated 2.0 & 3.0 are not compatible with Delegated 0.1.2. If you don't want to migrate your current codebase, stay on Delegated 0.1.2. See documentation for Delegated 0.1.2 here. If you need any help migrating from 0.1.x to 2.0.x, please open an issue.
🚨 WARNING! Delegated 3.0 uses variadic types which is only available on newer platforms and in Swift 5.9. If you don't want to migrate your current codebase, stay on Delegated 2.2.0. See documentation for Delegated 2.2.0 here. If you need any help migrating from 2.x to 3.x, please open an issue.
final class TextField {
var didUpdate: (String) -> () = { _ in }
}
// later...
self.textField.didUpdate = { [weak self] text in
guard let strongSelf = self else {
return
}
strongSelf.label.text = text
}final class TextField {
@Delegated var didUpdate: (String) -> ()
}
// later...
textField.$didUpdate.delegate(to: self) { (self, text) in
// `self` is weak automatically!
self.label.text = text
}No retain cycles! No memory leaks! No [weak self]! 🎉
final class TextField {
@Delegated var didUpdate: (String) -> ()
}You can also use @Delegated with any number of parameters:
final class TextField {
@Delegated var didStartEditing: () -> Void
@Delegated var didUpdate: (String) -> Void
@Delegated var didReplace: (String, String) -> Void
}// somewhere inside init() or viewDidLoad() or similar
self.textField = TextField()
textField.$didUpdate.delegate(to: self) { (self, text) in
self.label.text = text
}By default, delegate(to:with:) will wrap self in a weak reference so that you don't need to remember to write [weak self] every time. This is the main feature of Delegated, but if this is not the behavior you want, you can use manuallyDelegate(with:):
// somewhere inside init() or viewDidLoad() or similar
self.textField = TextField()
textField.$didUpdate.manuallyDelegate { (text) in
print(text)
}final class TextField {
@Delegated var didUpdate: (String) -> Void
/// ...
private func didFinishEditing() {
self.didUpdate(self.text)
}
}If your delegated function is designed to have a return value (non-Void), use @ReturningDelegated wrapper.
final class TextField {
@ReturningDelegated var shouldReturn: (String) -> Bool?
@ReturningDelegated var shouldBeginEditing: () -> Bool?
@ReturningDelegated var shouldReplace: (String, String) -> Bool?
}
// ...
textField.$shouldReturn.delegate(to: self) { (self, string) -> Bool in
if string.count > 5 {
return true
} else {
return false
}
}IMPORTANT: Make sure that your @ReturningDelegated function returns an optional. It will return nil if no delegate is set.
@Delegated var didUpdate: (String) -> ()
// ...
self.$didUpdate.removeDelegate()Use pipa(via:to:) function to quickly pass delegation up the chain
final class Button {
@Delegated var didPress: () -> Void
}
final class Alert {
@Delegated var didConfirm: () -> Void
@Delegated var didCancel: () -> Void
let confirmButton = Button()
let cancelButton = Button()
func didLoad() {
confirmButton.$didPress.pipe(via: self, to: \.$didConfirm)
cancelButton.$didPress.pipe(via: self, to: \.$didCancel)
}
}For @ReturningDelegate, use pipa(via:through:) function
Delegated is officially available only via Swift Package Manager.
In Xcode 11 or greater, in you project, select: File > Swift Packages > Add Pacakage Dependency
In the search bar type
https://github.com/dreymonde/Delegated
and when you find the package, with the next button you can proceed with the installation.
If you can't find anything in the panel of the Swift Packages you probably haven't added yet your github account. You can do that under the Preferences panel of your Xcode, in the Accounts section.
For command-line based apps, you can just add this directly to your Package.swift file:
dependencies: [
.package(url: "https://github.com/dreymonde/Delegated", from: "2.1.0"),
]Of course, you always have an option of just copying-and-pasting the code - Delegated is just one file, so feel free.