an example of an easy accident waiting to happen

hidden strong reference cycle closure.swift

//: Playground - noun: a place where people can play

import Foundation

class Bar {
	let doingSomething: () -> Void

	init(doingSomething: @escaping () -> Void) {
		self.doingSomething = doingSomething
	}
}

class Foo {
	var barSource: Bar!

	init() {

		// creates strong reference (resulting in retain cycle)
		barSource = Bar(doingSomething: anImplementationDoingSomething) // <-- this is what I'm talking about

		// creates a weak reference (fixing it)
//		barSource = Bar(doingSomething: { [weak self] in
//			self?.anImplementationDoingSomething()
//		})

		barSource.doingSomething()
	}

	func anImplementationDoingSomething() {
		print("it did!")
	}

	deinit {
		print("done with foo")
	}
}

func runloopSimulator() {
	_ = Foo()
}

runloopSimulator()