alternatives to notification registration; more async await updates

Author: mattneub

bk1ch05zp05MakeYourOwnAsyncStream/MakeYourOwnAsyncStream/Base.lproj/Main.storyboard

@@ -22,6 +22,15 @@
                                 <fontDescription key="fontDescription" type="system" pointSize="14"/>
                                 <textInputTraits key="textInputTraits"/>
                             </textField>
+                            <button opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="4rH-mb-Vcs">
+                                <rect key="frame" x="34" y="204" width="153" height="31"/>
+                                <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
+                                <state key="normal" title="Button"/>
+                                <buttonConfiguration key="configuration" style="plain" title="Cancel"/>
+                                <connections>
+                                    <action selector="doCancel:" destination="BYZ-38-t0r" eventType="touchUpInside" id="Rak-05-iRx"/>
+                                </connections>
+                            </button>
                         </subviews>
                         <viewLayoutGuide key="safeArea" id="6Tk-OE-BBY"/>
                         <color key="backgroundColor" systemColor="systemBackgroundColor"/>

bk1ch05zp05MakeYourOwnAsyncStream/MakeYourOwnAsyncStream/ViewController.swift

@@ -9,6 +9,11 @@ class TextFieldSelectionChangeStreamer: NSObject, UITextFieldDelegate {
         var myContinuation : AsyncStream<UITextField>.Continuation?
         self.values = AsyncStream { continuation in
             myContinuation = continuation
+            // I also tried to set the `onTermination` handler but couldn't; filed a bug
+            // ooo, Tyler Prevost has a workaround:
+            continuation.onTermination = { term in
+                print("terminated!")
+            } as (@Sendable (AsyncStream<UITextField>.Continuation.Termination) -> Void)
         }
         super.init()
         self.continuation = myContinuation
@@ -22,15 +27,32 @@ class TextFieldSelectionChangeStreamer: NSObject, UITextFieldDelegate {
 class ViewController: UIViewController {
     let textFieldSelectionChangeStreamer = TextFieldSelectionChangeStreamer()
     @IBOutlet var textField : UITextField?
+    var task : Task<Void, Never>?
     override func viewDidLoad() {
         super.viewDidLoad()
         self.textField?.delegate = self.textFieldSelectionChangeStreamer
-        Task {
+        let task = Task {
             for await textField in self.textFieldSelectionChangeStreamer.values {
                 print(textField.text ?? "")
             }
+            // let's unroll that so we can see what's actually happening
+//            var iter = self.textFieldSelectionChangeStreamer.values.makeAsyncIterator()
+//            for _ in 1...Int.max {
+//                if let tf = await iter.next() {
+//                    print(tf.text ?? "")
+//                } else {
+//                    print("I got nil")
+//                    break
+//                }
+//            }
         }
+        self.task = task
     }
+    // prove that an async stream is self-cancelling
+    @IBAction func doCancel (_ sender:Any) {
+        self.task?.cancel()
+    }
+
 
 
 }

bk1ch11p462notifications2/ObserverTest/ViewController2.swift

@@ -1,18 +1,42 @@
 
 
 import UIKit
+import Combine
 
 class ViewController2: UIViewController {
 
     static let notif = Notification.Name("notif")
 
+    var which = 1
 
+    // let's also add some alternative ways of getting notifications, namely by subscribing
+    var storage = Set<AnyCancellable>()
     override func viewDidAppear(_ animated: Bool) {
         super.viewDidAppear(animated)
-        print("registering observer")
-        let _ = NotificationCenter.default.addObserver(forName: ViewController2.notif, object: nil, queue: nil) { _ in
-            print("notification received")
+        
+        switch which {
+        case 0:
+            print("registering observer")
+            let _ = NotificationCenter.default.addObserver(forName: ViewController2.notif, object: nil, queue: nil) { _ in
+                print("notification received")
+            }
+        case 1:
+            print("subscribing with Combine")
+            NotificationCenter.default.publisher(for: ViewController2.notif)
+                .sink { _ in print("notification received") }
+                .store(in: &self.storage)
+        case 2:
+            print("subscribing with async stream")
+            let stream = NotificationCenter.default.notifications(named: ViewController2.notif)
+            Task {
+                for await _ in stream {
+                    print("notification received")
+                }
+            }
+        default: break
         }
+        
+        
     }
 
 }