Notification Demo

ViewController.swift

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        
        NSNotificationCenter.defaultCenter().addObserver(self, selector: "notificationReceived:", name: "bacon", object: nil)
        
        var url = NSURL(string: "ashdfhfd")
        
        // CRASH! Adding the bang (!) forces swift to unwrap the value. If it
        // unwraps and discovers a nil you get a crash.
//      println("\(url?.host!)")
        
        url = NSURL(string: "http//google.com")!
        
        // Instead, unwrap the optional. If the host is nil, then it'll just
        // skip over this code
        if let host = url?.host {
            let userInfo: NSDictionary = ["myKey" : host]
            NSNotificationCenter.defaultCenter().postNotificationName("bacon", object: nil, userInfo: userInfo as [NSObject : AnyObject])
        }
        
    }
    
    // Make sure you remove your observer when you're done
    deinit {
        NSNotificationCenter.defaultCenter().removeObserver(self)
    }
    
    func notificationReceived(notification: NSNotification) {
        if let message: AnyObject = notification.userInfo?["myKey"] {
            println("Zaid \(message)")
        }
    }

}