Weak Delegate

Delegates should be weak to avoid reference cycles

• Identifier: weak_delegate
• Enabled by default: No
• Supports autocorrection: No
• Kind: lint
• Analyzer rule: No
• Minimum Swift compiler version: 5.0.0
• Default configuration:

  Key	Value
  severity	warning

Non Triggering Examples

class Foo {
  weak var delegate: SomeProtocol?
}

class Foo {
  weak var someDelegate: SomeDelegateProtocol?
}

class Foo {
  weak var delegateScroll: ScrollDelegate?
}

class Foo {
  var scrollHandler: ScrollDelegate?
}

func foo() {
  var delegate: SomeDelegate
}

class Foo {
  var delegateNotified: Bool?
}

protocol P {
 var delegate: AnyObject? { get set }
}

class Foo {
 protocol P {
 var delegate: AnyObject? { get set }
}
}

class Foo {
 var computedDelegate: ComputedDelegate {
 return bar() 
} 
}

class Foo {
    var computedDelegate: ComputedDelegate {
        get {
            return bar()
        }
   }

struct Foo {
 @UIApplicationDelegateAdaptor(AppDelegate.self) var appDelegate 
}

struct Foo {
 @NSApplicationDelegateAdaptor(AppDelegate.self) var appDelegate 
}

struct Foo {
 @WKExtensionDelegateAdaptor(ExtensionDelegate.self) var extensionDelegate 
}

class Foo {
    func makeDelegate() -> SomeDelegate {
        let delegate = SomeDelegate()
        return delegate
    }
}

Triggering Examples

class Foo {
  ↓var delegate: SomeProtocol?
}

class Foo {
  ↓var scrollDelegate: ScrollDelegate?
}

class Foo {
    ↓var delegate: SomeProtocol? {
        didSet {
            print("Updated delegate")
        }
   }