OwnedDelegateAlertView

gistfile1.swift

//
//  ViewController.swift
//  deinit-failure
//
//  Created by Mike Parker on 2/26/15.
//  Copyright (c) 2015 Mike Parker. All rights reserved.
//

import UIKit



/**
 A UIAlertView that owns its delegate so that the client that displays the UIAlertView
 does not need to own it.

 This is useful when the client that displays the UIAlertView is not the UIAlertDelegate
 implementation. It is free to initialize an object to serve as the delegate that exists
 only for the lifetime of the UIAlertView, thereby fostering decomposition.
 */
private class OwnedDelegateAlertView: UIAlertView {
	private let ownedDelegate: UIAlertViewDelegate?

	override init(title: String?, message: String?, delegate: AnyObject?, cancelButtonTitle: String?) {
		ownedDelegate = delegate as UIAlertViewDelegate?

		super.init(title: title, message: message, delegate: nil, cancelButtonTitle: cancelButtonTitle)
	}

	convenience init(title: String, message: String, delegate: UIAlertViewDelegate, cancelButtonTitle: String, otherButtonTitles firstButtonTitle: String, _ moreButtonTitles: String...) {
		self.init(title: title, message: message, delegate: delegate, cancelButtonTitle: cancelButtonTitle)

		addButtonWithTitle(firstButtonTitle)
		for buttonTitle in moreButtonTitles {
			self.addButtonWithTitle(buttonTitle)
		}
	}

	required init(coder aDecoder: NSCoder) {
		fatalError("init(coder:) has not been implemented")
	}

	override init(frame: CGRect) { super.init(frame: frame) }

	deinit {
		println("running deinit for uialertview")
	}
}

/**
 UIAlertViewDelegate used when the user can only go back, and so the associated handler
 has no parameters.
 */
private class BackOnlyErrorDelegate: NSObject, UIAlertViewDelegate {
	private let handler: () -> Void

	init(handler: () -> Void) {
		self.handler = handler

		super.init()
	}

	func alertView(alertView: UIAlertView, clickedButtonAtIndex buttonIndex: Int) {
		switch buttonIndex {
		case alertView.cancelButtonIndex:
			handler()
		default:
			fatalError("UIAlertView selected an option that was not cancel")
		}
	}

	deinit {
		println("running deinit for delegate")
	}
}



class ViewController: UIViewController {
	override func viewDidLoad() {
		super.viewDidLoad()

		let delay = dispatch_time(DISPATCH_TIME_NOW, Int64(1 * Double(NSEC_PER_SEC)))
		dispatch_after(delay, dispatch_get_main_queue()) {
			self.displayAlertViewWithHandler(self.handlerForAlertView())
		}
	}

	private func displayAlertViewWithHandler(handler: () -> Void) {
		let delegate = BackOnlyErrorDelegate(handler: handler)

		let title = NSLocalizedString("the title", comment: "Title for alert view upon UIWebView failure")
		let message = "the message"
		let cancelButtonTitle = "cancel"

		let alertView = OwnedDelegateAlertView(title: title, message: message, delegate: delegate, cancelButtonTitle: cancelButtonTitle)
		alertView.show()
	}

	private func handlerForAlertView() -> () -> Void {
		return { [weak self] () -> Void in
			println("Handler invoked")
			return
		}
	}
}