new/revised chapter 11 exx

Author: mattneub

bk1ch11p462notifications3/NotificationRegistrationAlternatives/ViewController.swift

@@ -1,5 +1,6 @@
 
 import UIKit
+import MediaPlayer
 import Combine
 
 class ViewController: UIViewController {
@@ -9,6 +10,7 @@ class ViewController: UIViewController {
 
     var observers = Set<NSObject>()
     var storage = Set<AnyCancellable>()
+    var pipeline : AnyCancellable?
     var task : Task<(), Never>?
     override func viewDidLoad() {
         super.viewDidLoad()
@@ -37,6 +39,47 @@ class ViewController: UIViewController {
         default: break
         }
     }
+
+    func test() { // just showing syntax; these are not proper tests, that needs doing
+        do {
+            let ob = NotificationCenter.default.addObserver(
+                forName: .MPMusicPlayerControllerNowPlayingItemDidChange,
+                object: nil, queue: nil) { [unowned self] _ in
+                    self.updateNowPlayingItem()
+                    // ... and so on ...
+                }
+            self.observers.insert(ob as! NSObject)
+            // ...
+            for ob in self.observers {
+                NotificationCenter.default.removeObserver(ob)
+            }
+        }
+        do {
+            self.pipeline = NotificationCenter.default.publisher(
+                for: .MPMusicPlayerControllerNowPlayingItemDidChange)
+                    .sink { [unowned self] _ in
+                        self.updateNowPlayingItem()
+                        // ... and so on ...
+                    }
+            // ...
+            self.pipeline?.cancel()
+            self.pipeline = nil
+        }
+        do {
+            let stream = NotificationCenter.default.notifications(
+                named: .MPMusicPlayerControllerNowPlayingItemDidChange)
+            let task = Task {
+                for await _ in stream {
+                    self.updateNowPlayingItem()
+                    // ... and so on ...
+                }
+            }
+            self.task = task
+            // ...
+            self.task?.cancel()
+            self.task = nil
+        }
+    }
 
     @IBAction func unwind(_:UIStoryboardSegue) {}
 
@@ -54,5 +97,7 @@ class ViewController: UIViewController {
         // self.task = nil
     }
 
+    func updateNowPlayingItem() {}
+
 }
 

bk1ch11p466Timer/Timer/ViewController.swift

@@ -1,5 +1,6 @@
 
 import UIKit
+import Combine
 
 class ViewController: UIViewController {
 
@@ -26,6 +27,30 @@ class ViewController: UIViewController {
         print("fired2")
     }
 
+    var pipeline : AnyCancellable?
+    func test() {
+        // just showing syntax
+        self.pipeline = Timer.publish(every: 1, on: .main, in: .default)
+            .autoconnect()
+            .sink { print("timer fired at", $0) }
+        // ...
+        self.pipeline = nil
+    }
+    var task : Task<(), Never>?
+    func test2() {
+        // ditto
+        let timerpub = Timer.publish(every: 1, on: .main, in: .default)
+            .autoconnect()
+        self.task = Task {
+            for await value in timerpub.values {
+                print("timer fired at", value)
+            }
+        }
+        // ...
+        self.task?.cancel()
+        self.task = nil
+    }
+
 
 }
 

bk1ch11p472action2/bk1ch11p472action/ViewController.swift

@@ -48,5 +48,28 @@ class ViewController: UIViewController {
 
     @IBAction func unwind(_ sender: UIStoryboardSegue) {}
 
+    var myButton : UIButton = UIButton()
+    func test() {
+        let action = UIAction { [unowned self] _ in
+            let alert = UIAlertController(
+                title: "Howdy!", message: "You tapped me!", preferredStyle: .alert)
+            alert.addAction(
+                UIAlertAction(title: "OK", style: .cancel))
+            self.present(alert, animated: true)
+        }
+        self.myButton.addAction(action, for: .touchUpInside)
+    }
+    func test2() {
+        let action = UIAction { action in
+            if var resp = action.sender as? UIResponder {
+                while let r = resp.next {
+                    print(r); resp = r
+                }
+            }
+        }
+        self.myButton.addAction(action, for: .touchUpInside)
+
+    }
+
 }
 

bk1ch11p477kvo/ch13p355kvo/AppDelegate.swift

@@ -32,7 +32,7 @@ class Observer {
 
     func register(with observed:Observed) {
         let opts : NSKeyValueObservingOptions = [.old, .new]
-        let ob = observed.observe(\.value, options: opts) { obj, change in
+        let ob = observed.observe(\.value, options:opts) { obj, change in
             // obj is the observed object
             // change is an NSKeyValueObservedChange
             if let oldValue = change.oldValue {
@@ -46,7 +46,7 @@ class Observer {
             // yes, we can leak if we don't say unowned self
         }
         // the observer must live long enough for the function to be executed
-        obs.insert(ob)
+        self.obs.insert(ob)
     }
 
 

bk1ch11p480delayExample/delayExample/ViewController.swift

@@ -42,18 +42,23 @@ class TracksViewController : UIViewController {
 
 class ViewController: UITableViewController {
     let albums = [String]()
-    
+    var which = 0
     override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
-//        delay(0.1) {
-//        let t = TracksViewController(
-//            mediaItemCollection: self.albums[indexPath.row])
-//        self.navigationController?.pushViewController(t, animated: true)
-//        }
-        Task {
-            await Task.sleep(0.1)
+        switch which {
+        case 0:
+            delay(0.1) {
             let t = TracksViewController(
                 mediaItemCollection: self.albums[indexPath.row])
             self.navigationController?.pushViewController(t, animated: true)
+            }
+        case 1:
+            Task {
+                await Task.sleep(0.1)
+                let t = TracksViewController(
+                    mediaItemCollection: self.albums[indexPath.row])
+                self.navigationController?.pushViewController(t, animated: true)
+            }
+        default: break
         }
     }