Overview:
When running the demo code presented in "The SwiftUI cookbook for navigation" (https://developer.apple.com/wwdc22/10054) I ran into some issues:
Runtime warnings:
2022-06-08 22:20:31.587169+0800 NavigationSplitViewDemo[17797:672165] [SwiftUI] A NavigationLink is presenting a value of type “Category” but there is no matching navigation destination visible from the location of the link. The link cannot be activated.
onChange(of: UpdateTrigger) action tried to update multiple times per frame.
2022-06-08 22:15:23.432289+0800 NavigationSplitViewDemo[17645:662571] [UIFocus] _TtGC7SwiftUI14_UIHostingViewGVS_15ModifiedContentVS_7AnyViewVS_12RootModifier__ implements focusItemsInRect: - caching for linear focus movement is limited as long as this view is on screen.
Feedback filed:
FB10103041 and FB10104196
Post not yet marked as solved
Overview
I have an existing Xcode project that works fine with Xcode Cloud
I have a separate branch on to which I have migrated and made changes for Xcode 14
On the same branch I have made some code changes that is supported by Swift 5.7
Example:
var price: Int? = 100
guard let price else {
return
}
Problem
Xcode code build fails with the error Variable binding in a condition requires an initializer
Question:
Is it possible to build Xcode Cloud on Swift 5.7 or Xcode 14?
Hi,
My lab appointment status is pending. The lab is for tomorrow.
When would I get to know if my lab appointment has been accepted.
It is my first time for a lab appointment, also I forgot to mention the feedback IDs, would there be a way to amend the request to include the feedback IDs if that would help. (Feedback assistant was down when I booked an appointment so couldn't get the feedback IDs.)
Any help would be much appreciated as I am from a different timezone and would need to plan accordingly .... really praying I get an appointment
Post not yet marked as solved
I am a bit confused about tasks being cancelled.
Overview:
checkCancellation function has 2 child tasks: computeA and computeB that run concurrently,
computeB throws an error.
Doubt:
I expected child task computeA to be cancelled because computeB threw an error, but computeA was never cancelled.
Is my understanding wrong or am I missing something?
Or is this a bug?
Note:
I am using a SwiftUI project (as Swift Playgrounds don't support async let)
macOS Big Sur 11.5.2 (20G95)
Xcode Version 13.0 beta 5 (13A5212g)
Output:
A - started
B - going to throw
A - going to return, Task.isCancelled = false
error: infinity
Concurrent Function Definitions:
import Foundation
import UIKit
enum ComputationError: Error {
case infinity
}
fileprivate func computeA() async throws -> Int {
print("A - started")
await Task.sleep(2 * 100_000_000)
print("A - going to return, Task.isCancelled = \(Task.isCancelled)") //I expected Task.isCancelled to be true
return 25
}
fileprivate func computeB() async throws -> Int {
print("B - going to throw")
throw ComputationError.infinity
}
func checkCancellation() async throws {
async let a = computeA()
async let b = computeB()
let c = try await a + b
print("c = \(c)")
}
Invoking Concurrent function
struct ContentView: View {
var body: some View {
Button("check cancellation") {
Task {
do {
try await checkCancellation()
print("normal exit")
} catch {
print("error: \(error)")
}
}
}
}
}
Post not yet marked as solved
Aim
To use a keyboard shortcut on a Multiplatform app (iOS and macOS)
When keyboard shortcut is tapped, the price needs to be printed
Problem
The same code doesn't work on iPad but works on macOS
Question:
Why is not working?
How to fix this?
Environment
macOS Big Sur - 11.6 (20G165)
Version 13.0 (13A233)
Code
@main
struct TestApp: App {
@State private var price = 0
var body: some Scene {
WindowGroup {
ContentView(price: $price)
.focusedValue(\.price, $price)
}
.commands {
PriceCommands()
}
}
}
struct ContentView: View {
@Binding var price: Int
var body: some View {
IncreasePriceButton(price: $price)
}
}
struct IncreasePriceButton: View {
@Binding var price: Int
var body: some View {
Button("Increase Price") {
price += 1
print("price = \(price)")
}
}
}
struct PriceCommandButton: View {
@FocusedBinding(\.price) var price
var body: some View {
Button("Print Price") {
print("price = \(price)")
}
}
}
struct PriceCommands: Commands {
var body: some Commands {
CommandMenu("Custom") {
PriceCommandButton()
.keyboardShortcut(KeyboardShortcut("C", modifiers: [.command, .shift]))
}
}
}
struct FocusedPriceKey: FocusedValueKey {
typealias Value = Binding<Int>
}
extension FocusedValues {
var price: FocusedPriceKey.Value? {
get { self[FocusedPriceKey.self] }
set { self[FocusedPriceKey.self] = newValue }
}
}
Aim:I have a model which is an ObservableObject. It has a Bool property, I would like to use this Bool property to initialise a @Binding variable.Questions:How to convert an @ObservableObject to a @Binding ?Is creating a @State the only way to initialise a @Binding ?Note:I do understand I can make use of @ObservedObject / @EnvironmentObject, and I see it's usefulness, but I am not sure a simple button needs to have access to the entire model.Or is my understanding incorrect ?Code:import SwiftUI
import Combine
import SwiftUI
import PlaygroundSupport
class Car : ObservableObject {
@Published var isReadyForSale = true
}
struct SaleButton : View {
@Binding var isOn : Bool
var body: some View {
Button(action: {
self.isOn.toggle()
}) {
Text(isOn ? "On" : "Off")
}
}
}
let car = Car()
//How to convert an ObservableObject to a Binding
//Is creating an ObservedObject or EnvironmentObject the only way to handle a Observable Object ?
let button = SaleButton(isOn: car.isReadyForSale) //Throws a compilation error and rightly so, but how to pass it as a Binding variable ?
PlaygroundPage.current.setLiveView(button)
Post not yet marked as solved
Hi,I am trying to extract the data from the P8 file to use it generate JWT.I understand that it is possible using dumpasn1 and extracting the OCTET STRING section. This is great, and is definitely possible.I was wondering if it was possible to do it on macOS using Apple's APIs (example SecItemImport), would make it simpler if it was possible all in the mac app.I tried the following but it didn't work:Error: I got the OSStatus as -25257Questions:- Is there a way to do this using SecItemImport or any other Apple APIs as I am using it in a command line mac app ?- Are the parameters to SecItemImport are incorrect ?- Am down the wrong path? , any direction to the correct API would help.What I tried with SecItemImport:- Data extracted from the file- Decoding the data from the file- Some input formatsMany thanks.import Foundation
import Security
func f1() {
do {
let fileURL = URL(fileURLWithPath: "some valid path");
let data = try Data(contentsOf: fileURL)
guard let string = String(data: data, encoding: .utf8) else {
print("Failed to convert data to string")
return
}
let b64Text = string
.replacingOccurrences(of: "-----END PRIVATE KEY-----", with: "")
.replacingOccurrences(of: "-----BEGIN PRIVATE KEY-----", with: "")
.replacingOccurrences(of: "\n", with: "")
guard let b64Data = b64Text.data(using: .utf8),
let decodedData = Data(base64Encoded: b64Data) else {
print("Was not b64 data")
return
}
print(string)
var outArray : CFArray?
let filename : CFString? = nil
var inputFormat = SecExternalFormat.formatUnknown
var itemType = SecExternalItemType.itemTypePrivateKey
let flags = SecItemImportExportFlags()
//I tried data, b64Data, decodedData all seems to return an error
let status = SecItemImport(decodedData as CFData,
filename,
&inputFormat,
&itemType,
flags,
nil,
nil,
&outArray)
//status = -25257
print("status = \(status)")
for element in (outArray as [AnyObject]?) ?? [] {
print("element = \(element)")
}
}
catch {
print("Error: \(error)")
}
}
f1()
Hi,I would like to create a JWT to interact with Apple's Webservices.As the first step, I have a private key file, I have loaded it as Data.I would like to create an instance of Private Key instance (not sure what is the correct struct to use, tried HMAC, P256.Signing.PrivateKey etc)Every time an exception is thrown.Any help and direction would greatly help. Many thanks.let privateKeyPath = URL(fileURLWithPath: "some valid path")
let privateKeyData = try Data(contentsOf: privateKeyPath, options: .alwaysMapped)
let message = "abcd"
let messageData = message.data(using: .utf8)!
do {
//Option1:
//This throws: Error: incorrectParameterSize
let signature1 = try P256.Signing.ECDSASignature(rawRepresentation: privateKeyData)
//Option2:
let key2 = SymmetricKey(data: privateKeyData)
//This throws: Error: incorrectKeySize
var encryptedContent2 = try AES.GCM.seal(messageData, using: key2).combined
}
catch {
print("Error: \(error)")
}
Aim
I would like to display an alert, when the user dismisses the alert the next alert should be displayed.
If the user doesn't dismiss the first alert, the 2nd alert should wait till the user dismisses the first alert
Functionality like back pressure.
My Attempt:
Given below is code where I have attempted to do it based on an @ObservedObject and @Published property.
Problem:
Alerts are displayed but they don't wait for the alert to be dismissed.
Code:
ContentView:
import SwiftUI
struct ContentView: View {
@ObservedObject var model = Model()
var body: some View {
Text("Hello World!")
.alert(item: $model.employee, content: makeAlert(forEmployee:))
}
private func makeAlert(forEmployee employee: Employee) -> Alert {
let dismissButton = Alert.Button.cancel((Text("Ok")))
return Alert(title: Text("New Employee"),
message: Text(employee.name),
dismissButton: dismissButton)
}
}
Model:
import Foundation
class Model : ObservableObject {
@Published var employee : Employee?
private var index = 0
private lazy var timer = {
Timer.scheduledTimer(withTimeInterval: 3, repeats: true) { [weak self] timer in
self?.createNewEmployee()
print("fired for \(self?.employee?.name ?? "none")")
}
}()
init() {
timer.fire()
}
func createNewEmployee() {
guard let unicodeScalar = UnicodeScalar(index + 65) else {
return
}
let name = String(Character(unicodeScalar))
employee = Employee(id: index,
name: name)
index += 1
}
}
Employee:
import Foundation
class Employee : Identifiable {
var id : Int
var name : String
init(id: Int, name: String) {
self.id = id
self.name = name
}
}
What I had done:I enabled full screen mode on the simulator so I executed the following command:defaults write com.apple.iphonesimulator AllowFullscreenMode -bool YESQuestion:How can I remove this rectangular bar shown in the image (so that it is like the default setting when xcode is installed)?I have tried the following without any success:Executed the above command with a NODeleted /Users/<Username>/Library/Preferences/com.apple.iphonesimulator.plistCreated a new Mac UserDeleted Xcode and installed it again
Post not yet marked as solved
I have created an AsyncOperation which is a subclass of Operation.I am overriding the following methods to use KVC:- isExecuting- isFinishedProblem:When I use String in place of KeyPath, my completion block gets executed. If I use KeyPath the completion block of the operation is not getting executed.Works ok:willChangeValue(forKey: "isExecuting")didChangeValue(forKey: "isExecuting")willChangeValue(forKey: "isFinished")didChangeValue(forKey: "isFinished")Doesn't work (Compiles ok, but at runtime the completion block doesn't get executed):willChangeValue(for: \.isExecuting)didChangeValue(for: \.isExecuting)willChangeValue(for: \.isFinished)didChangeValue(for: \.isFinished)Note: I am using the following:- macOS 10.12.5 (16F73)- Xcode 9.0 beta (9M136h)Questions:1. Why isn't KeyPath working when using the String works ?2. How to fix using KeyPath ?Complete Code:class AsyncOperation : Operation {
private var _executing = false
private var _finished = false
override var isExecuting : Bool {
get {
return _executing
}
set {
willChangeValue(for: \.isExecuting
_executing = newValue
didChangeValue(for: \.isExecuting)
}
}
override var isFinished : Bool {
get {
return _finished
}
set {
willChangeValue(for: \.isFinished)
_finished = newValue
didChangeValue(for: \.isFinished)
}
}
override var isAsynchronous : Bool {
return true
}
func markAsCompleted() {
isExecuting = false
isFinished = true
}
}
Post not yet marked as solved
Overview:I have a class called Player and a class called Song.Player contains a SongA view is showing the song titleAim:When I change the player.song.title, the view needs to be updated.
Problem:When the song's attributes changes, it wouldn't update the view automatically. Only when a new song is assigned will the changes be reflected.My Attempts:I have made 2 attempts (code below), both work as expected.Questions:Is there a better way to do it ? (It seems like a common problem, one would encounter.)Are my attempts reasonable and is attempt 2 better?Or is there something fundamentally flawed with my design? (I was hoping to have the song inside the player because it represented the current song).Original Code (view wouldn't be updated):Modelimport Foundation
import Combine
class Player : ObservableObject {
@Published var duration = 0
@Published var song : Song
init(song: Song) {
self.song = song
}
}
class Song : ObservableObject {
@Published var id : Int
@Published var title : String
@Published var artist : String
init(id: Int,
title: String,
artist: String) {
self.id = id
self.title = title
self.artist = artist
}
}View:import SwiftUI
struct ContentView: View {
@ObservedObject var player : Player
var body: some View {
VStack {
Text(String(player.duration))
Text(player.song.title)
Text(player.song.artist)
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
let song = Song(id: 1, title: "title1", artist: "artist1")
let player = Player(song: song)
DispatchQueue.main.asyncAfter(deadline: .now() + 2) {
player.song.title = "title2"
}
return ContentView(player: player)
}
}Attempt1 - Using CombineLatestProblem: It is not very scalable as the number of properties in a song increases.class Player : ObservableObject {
@Published var duration = 0
@Published var song : Song
private var songChangeCanceller : AnyCancellable?
init(song: Song) {
self.song = song
songChangeCanceller = song.$title.combineLatest(song.$artist, song.$id).sink { _, _, _ in
self.objectWillChange.send()
}
}
}Attemp2: Uses objectWillChange.sinkclass Player : ObservableObject {
@Published var duration = 0
@Published var song : Song
private var songChangeCanceller : AnyCancellable?
private var songAttributesChangeCanceller : AnyCancellable?
init(song: Song) {
self.song = song
songChangeCanceller = $song.sink { newSong in
self.songAttributesChangeCanceller = newSong.objectWillChange.sink { _ in
self.objectWillChange.send()
}
}
}
}
Hi,I have created a new command line tool project, where I am trying to add a key to the keychain.Error:OSStatus: -34018Error Description: A required entitlement isn't present.Questions:1. How can I resolve this error ? I am able to do the same thing using a mac app instead of a command line tool project.2. Am I missing some key steps ?Points to note:- Signing: Automatically manage Signing- Signing certificate - Developmentmain.swiftimport Foundation
import CryptoKit
func storeKey(label: String) {
//Generate key
let key = P256.Signing.PrivateKey()
let attributes = [kSecAttrKeyType: kSecAttrKeyTypeECSECPrimeRandom,
kSecAttrKeyClass: kSecAttrKeyClassPrivate] as [String: Any]
// Get a SecKey representation.
guard let secKey = SecKeyCreateWithData(key.x963Representation as CFData,
attributes as CFDictionary,
nil) else {
print("Unable to create SecKey representation.")
return
}
let query = [kSecClass: kSecClassKey,
kSecAttrApplicationLabel: label,
kSecAttrAccessible: kSecAttrAccessibleWhenUnlocked,
kSecUseDataProtectionKeychain: true,
kSecValueRef: secKey] as [String: Any]
// Add the key to the keychain.
let status = SecItemAdd(query as CFDictionary, nil)
guard status == errSecSuccess else {
print("Unable to store item: \(status)")
print(SecCopyErrorMessageString(status, nil) ?? "")
return
}
print("successful")
}
storeKey(label: "TEST-KeyChain-Mac")Attempts made:1. Add Info.plist (contents shown below)2. Add TestExample.entitlements (contents shown below)After adding entitlements I get the following error:Message from debugger: Error 1Program ended with exit code: -1Build Settings Changes:CODE_SIGN_ENTITLEMENTS = TestExample/TestExample.entitlements
CODE_SIGN_INJECT_BASE_ENTITLEMENTS
INFOPLIST_FILE = TestExample/Info.plist
CREATE_INFOPLIST_SECTION_IN_BINARY = YES
PRODUCT_BUNDLE_IDENTIFIER = .TestExampleInfo.plist<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>CFBundleIdentifier</key>
<string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
<key>CFBundleName</key>
<string>$(PRODUCT_NAME)</string>
</dict>
</plist>TestExample.entitlements<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>keychain-access-groups</key>
<array>
<string>$(AppIdentifierPrefix)<same reverse DNS>.TestExample</string>
</array>
</dict>
</plist>
Hi, I would like to perform AES ECB (128 bits) encryption.I understand CryptoKit is available however I could only see AES GCM encryption.Questions:- Is it possible to do AES ECB encryption using CryptoKit ? - For older OS (example less than iOS 13 and macOS 10.15) what is the recommended framework / approach ? - Is there is any code sample / documentation / video on using the alternate framework ? (would help me as I am new to encryption)Note: I was hoping to use native frameworks as much as possible but was also scared of doing it on my own as I am new to it.Many thanks.
Post not yet marked as solved
HiI have CKFetchRecordZoneChangesOperation with a recordZoneChangeTokensUpdatedBlockrecordZoneChangeTokensUpdatedBlock is getting called multiple times.Inside recordZoneChangeTokensUpdatedBlock, I try to save the records that are received upto that point in time (collected from recordChangedBlock) and save the server change token so that if the operation fails at a later point, re-creating another CKFetchRecordZoneChangesOperation could use the server change token that was cached and need not fetch from scratch. References:This approach was explained inhttps://developer.apple.com/library/content/documentation/DataManagement/Conceptual/CloudKitQuickStart/MaintainingaLocalCacheofCloudKitRecords/MaintainingaLocalCacheofCloudKitRecords.htmlWhat's New with CloudKitProblem:The records received upto that point are not in order. For example: I have a master and transaction record types. I receive 5 transaction records without a single master record. So when I try to save them the records are in an inconsistent state for the app to function. Note: When I saved the records, I saved master and transactions records in a single operation and was saved successfully (using CKModifyRecordsOperation)Workaround:I can use the fetchRecordZoneChangesCompletionBlock to save the records into the local cache (Core Data), but for a large operation which fetches a lot of changes with multiple change tokens the user has to wait till the operation completes (as opposed to seeing batches of changes)My Understanding:- Based on the video and the documentation, I thought the recordChangedBlock would be called sequentially so that in the recordZoneChangeTokensUpdatedBlock we can save the records changes that have accumulated so far and be in a consistent state.I really hope someone can help me on this as this. Thanks.
newwbee.