I'm new to Swift (but not to programming). I have simple app that provides an alert based on specific conditionals. I would like to execute a function (or even just set a variable) when one of the buttons is pressed. Ideally, I just need one button, but if for whatever reason, only the notification.actionButtonTitle can have a handler, that's fine with me.
My notification code is currently in a Swift file as a helper.
import Foundation
class NotificationHelper {
static func sampleNotification(notification: NSUserNotification) {
let notificationCenter = NSUserNotificationCenter.default
notification.identifier = "unique-id-123"
notification.hasActionButton = true
notification.otherButtonTitle = "Close"
notification.actionButtonTitle = "Show"
notification.title = "Hello"
notification.subtitle = "How are you?"
notification.informativeText = "This is a test"
notificationCenter.deliver(notification)
}
}
Currently in AppDelegate, this is defined:
let notification = NSUserNotification()
…and I call the notification like this:
NotificationHelper.sampleNotification(notification: notification)
The resulting notification works, as you can see in the screenshot below. However, I cannot seem to listen to the button action. I have tried adding this to the AppDelegate as well as the NotificationHelper file, but I did not have any success with it:
func userNotificationCenter(center: NSUserNotificationCenter, didActivateNotification notification: NSUserNotification) {
print("checking notification response")
}
Any idea of what I'm missing?
Thanks!
You'll need to assign something as the delegate of the NSUserNotificationCenter:
NSUserNotificationCenter.default.delegate = self
If you add this to your AppDelegate and make your AppDelegate conform to NSUserNotificationCenterDelegate:
class AppDelegate: NSObject, NSUserNotificationCenterDelegate {
}
Related
I am building an iOS app using the new language Swift. Now it is an HTML5 app, that displays HTML content using the UIWebView. The app has local notifications, and what i want to do is trigger a specific javascript method in the UIWebView when the app enters foreground by clicking (touching) the local notification.
I have had a look at this question, but it does not seem to solve my problem. I have also come across this question which tells me about using UIApplicationState, which is good as that would help me know the the app enters foreground from a notification. But when the app resumes and how do i invoke a method in the viewController of the view that gets displayed when the app resumes?
What i would like to do is get an instance of my ViewController and set a property in it to true. Something as follows
class FirstViewController: UIViewController,UIWebViewDelegate {
var execute:Bool = false;
#IBOutlet var tasksView: UIWebView!
}
And in my AppDelegate i have the method
func applicationWillEnterForeground(application: UIApplication!) {
let viewController = self.window!.rootViewController;
let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
var setViewController = mainStoryboard.instantiateViewControllerWithIdentifier("FirstView") as FirstViewController
setViewController.execute = true;
}
so what i would like to do is when the app enters foreground again, i want to look at the execute variable and run the method as follows,
if execute{
tasksView.stringByEvaluatingJavaScriptFromString("document.getElementById('sample').click()");
}
Where should i put the code for the logic to trigger the javascript from the webview? would it be on viewDidLoad method, or one of the webView delegate methods? i have tried to put that code in the viewDidLoad method but the value of the boolean execute is set to its initial value and not the value set in the delegate when the app enters foreground.
If I want a view controller to be notified when the app is brought back to the foreground, I might just register for the UIApplication.willEnterForegroundNotification notification (bypassing the app delegate method entirely):
class ViewController: UIViewController {
private var observer: NSObjectProtocol?
override func viewDidLoad() {
super.viewDidLoad()
observer = NotificationCenter.default.addObserver(forName: UIApplication.willEnterForegroundNotification, object: nil, queue: .main) { [unowned self] notification in
// do whatever you want when the app is brought back to the foreground
}
}
deinit {
if let observer = observer {
NotificationCenter.default.removeObserver(observer)
}
}
}
Note, in the completion closure, I include [unowned self] to avoid strong reference cycle that prevents the view controller from being deallocated if you happen to reference self inside the block (which you presumably will need to do if you're going to be updating a class variable or do practically anything interesting).
Also note that I remove the observer even though a casual reading of the removeObserver documentation might lead one to conclude is unnecessary:
If your app targets iOS 9.0 and later or macOS 10.11 and later, you don't need to unregister an observer in its dealloc method.
But, when using this block-based rendition, you really do need to remove the notification center observer. As the documentation for addObserver(forName:object:queue:using:) says:
To unregister observations, you pass the object returned by this method to removeObserver(_:). You must invoke removeObserver(_:) or removeObserver(_:name:object:) before any object specified by addObserver(forName:object:queue:using:) is deallocated.
I like to use the Publisher initializer of NotificationCenter. Using that you can subscribe to any NSNotification using Combine.
import UIKit
import Combine
class MyFunkyViewController: UIViewController {
/// The cancel bag containing all the subscriptions.
private var cancelBag: Set<AnyCancellable> = []
override func viewDidLoad() {
super.viewDidLoad()
addSubscribers()
}
/// Adds all the subscribers.
private func addSubscribers() {
NotificationCenter
.Publisher(center: .default,
name: UIApplication.willEnterForegroundNotification)
.sink { [weak self] _ in
self?.doSomething()
}
.store(in: &cancelBag)
}
/// Called when entering foreground.
private func doSomething() {
print("Hello foreground!")
}
}
Add Below Code in ViewController
override func viewDidLoad() {
super.viewDidLoad()
let notificationCenter = NotificationCenter.default
notificationCenter.addObserver(self, selector:#selector(appMovedToForeground), name: UIApplication.willEnterForegroundNotification, object: nil)
}
#objc func appMovedToForeground() {
print("App moved to foreground!")
}
In Swift 3, it replaces and generates the following.
override func viewDidLoad() {
super.viewDidLoad()
foregroundNotification = NotificationCenter.default.addObserver(forName:
NSNotification.Name.UIApplicationWillEnterForeground, object: nil, queue: OperationQueue.main) {
[unowned self] notification in
// do whatever you want when the app is brought back to the foreground
}
This seems to be specific to iOS 13.1, as it works as expected on iOS 13.0 and earlier versions to add a contact in CNContactViewController, if I 'Cancel', the action sheet is overlapping by keyboard. No actions getting performed and keyboard is not dismissing.
Kudos to #GxocT for the the great workaround! Helped my users immensely.
But I wanted to share my code based on #GxocT solution hoping it will help others in this scenario.
I needed my CNContactViewControllerDelegate contactViewController(_:didCompleteWith:) to be called on cancel (as well as done).
Also my code was not in a UIViewController so there is no self.navigationController
I also dont like using force unwraps when I can help it. I have been bitten in the past so I chained if lets in the setup
Here's what I did:
Extend CNContactViewController and place the swizzle function in
there.
In my case in the swizzle function just call the
CNContactViewControllerDelegate delegate
contactViewController(_:didCompleteWith:) with self and
self.contact object from the contact controller
In the setup code, make sure the swizzleMethod call to
class_getInstanceMethod specifies the CNContactViewController
class instead of self
And the Swift code:
class MyClass: CNContactViewControllerDelegate {
override func viewDidLoad() {
super.viewDidLoad()
self.changeImplementation()
}
func changeCancelImplementation() {
let originalSelector = Selector(("editCancel:"))
let swizzledSelector = #selector(CNContactViewController.cancelHack)
if let originalMethod = class_getInstanceMethod(object_getClass(CNContactViewController()), originalSelector),
let swizzledMethod = class_getInstanceMethod(object_getClass(CNContactViewController()), swizzledSelector) {
method_exchangeImplementations(originalMethod, swizzledMethod)
}
}
func contactViewController(_ viewController: CNContactViewController, didCompleteWith contact: CNContact?) {
// dismiss the contacts controller as usual
viewController.dismiss(animated: true, completion: nil)
// do other stuff when your contact is canceled or saved
...
}
}
extension CNContactViewController {
#objc func cancelHack() {
self.delegate?.contactViewController?(self, didCompleteWith: self.contact)
}
}
The keyboard still shows momentarily but drops just after the Contacts controller dismisses.
Lets hope apple fixes this
I couldn't find a way to dismiss keyboard. But at least you can pop ViewController using my method.
Don't know why but it's impossible to dismiss keyboard in CNContactViewController. I tried endEditing:, make new UITextField firstResponder and so on. Nothing worked.
I tried to alter action for "Cancel" button. You can find this button in NavigationController stack, But it's action is changed every time you type something.
Finally I used method swizzling. I couldn't find a way to dismiss keyboard as I mentioned earlier, but at least you can dismiss CNContactViewController when "Cancel" button is pressed.
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
changeImplementation()
}
#IBAction func userPressedButton(_ sender: Any) {
let controller = CNContactViewController(forNewContact: nil)
controller.delegate = self
navigationController?.pushViewController(controller, animated: true)
}
#objc func popController() {
self.navigationController?.popViewController(animated: true)
}
func changeImplementation() {
let originalSelector = Selector("editCancel:")
let swizzledSelector = #selector(self.popController)
if let originalMethod = class_getInstanceMethod(object_getClass(CNContactViewController()), originalSelector),
let swizzledMethod = class_getInstanceMethod(object_getClass(CNContactViewController()), swizzledSelector) {
method_exchangeImplementations(originalMethod, swizzledMethod)
}
}
}
PS: You can find additional info on reddit topic: https://www.reddit.com/r/swift/comments/dc9n3a/bug_with_cnviewcontroller_ios_131/
Fixed in iOS 13.4
Tested in Xcode Simulator
NOTE: This bug is now fixed. This question and answer were applicable only to some particular versions of iOS (a limited range of iOS 13 versions).
The user can in fact swipe down to dismiss the keyboard and then tap Cancel and see the action sheet. So this issue is regrettable and definitely a bug (and I have filed a bug report) but not fatal (though, to be sure, the workaround is not trivial for the user to discover).
Thanks, #GxocT for your workaround, however, the solution posted here is different from the one you posted on Reddit.
The one on Reddit works for me, this one doesn't so I want to repost it here.
The difference is on the line with swizzledMethod which should be:
let swizzledMethod = class_getInstanceMethod(object_getClass(self), swizzledSelector) {
The whole updated code is:
class MyClass: CNContactViewControllerDelegate {
override func viewDidLoad() {
super.viewDidLoad()
self.changeImplementation()
}
func changeCancelImplementation() {
let originalSelector = Selector(("editCancel:"))
let swizzledSelector = #selector(CNContactViewController.cancelHack)
if let originalMethod = class_getInstanceMethod(object_getClass(CNContactViewController()), originalSelector),
let swizzledMethod = class_getInstanceMethod(object_getClass(self), swizzledSelector) {
method_exchangeImplementations(originalMethod, swizzledMethod)
}
}
func contactViewController(_ viewController: CNContactViewController, didCompleteWith contact: CNContact?) {
// dismiss the contacts controller as usual
viewController.dismiss(animated: true, completion: nil)
// do other stuff when your contact is canceled or saved
...
}
}
extension CNContactViewController {
#objc func cancelHack() {
self.delegate?.contactViewController?(self, didCompleteWith: self.contact)
}
}
Thanks #Gxoct for his excellent work around. I think this is very useful question & post for those who are working with CNContactViewController. I also had this problem (till now) but in objective c. I interpret the above Swift code into objective c.
- (void)viewDidLoad {
[super viewDidLoad];
Class class = [CNContactViewController class];
SEL originalSelector = #selector(editCancel:);
SEL swizzledSelector = #selector(dismiss); // we will gonna access this method & redirect the delegate via this method
Method originalMethod = class_getInstanceMethod(class, originalSelector);
Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector);
BOOL didAddMethod =
class_addMethod(class,
originalSelector,
method_getImplementation(swizzledMethod),
method_getTypeEncoding(swizzledMethod));
if (didAddMethod) {
class_replaceMethod(class,
swizzledSelector,
method_getImplementation(originalMethod),
method_getTypeEncoding(originalMethod));
} else {
method_exchangeImplementations(originalMethod, swizzledMethod);
}
}
Creating a CNContactViewController category for accessing dismiss;
#implementation CNContactViewController (Test)
- (void) dismiss{
[self.delegate contactViewController:self didCompleteWithContact:self.contact];
}
#end
Guys who are not so familiar with Swizzling you may try this post by matt
One thing to always take into account is that swizzler method is executed only once. Make sure that you implement changeCancelImplementation() in dispatch_once queue so that it is executed only once.
Check this link for description
Also this bug is found only in iOS 13.1, 13.2 and 13.3
I'm teaching myself Swift (currently using Xcode 7.3) and I'm working with storyboards for the first time. I'm writing an OS X-based app and I want to display an alert when the user attempts to load data when data already exists. I've read the following thread, Add completion handler to presentViewControllerAsSheet but I'm having trouble wrapping my head around closures/completion handlers. I understand them "in theory" but not yet well enough to write one.
In the thread above, a Struct is being returned. I just need to return an Int or Bool to indicate whether the user wants to overwrite the data or not.
You don't need to create a second view controller. Just configure and display an NSAlert object:
#IBAction func loadData(sender : AnyObject) {
let dataAlreadyExists = true // assume this is always true
if dataAlreadyExists {
let alert = NSAlert()
alert.messageText = "Do you want to reload data?"
alert.addButtonWithTitle("Reload")
alert.addButtonWithTitle("Do not reload")
alert.beginSheetModalForWindow(self.view.window!) { response in
if response == NSAlertFirstButtonReturn {
// reload data
}
}
}
}
I am currently making a XIB Menu Bar application that displays a notification using this code:
func showNotification(message:String, title:String = "App Name") -> Void {
let notification = NSUserNotification()
notification.title = title
notification.informativeText = message
NSUserNotificationCenter.defaultUserNotificationCenter().deliverNotification(notification)
}
And calling it like this:
showNotification("\(song)\n\(artist)",title: "Now Playing")
The notification works when the Menu Bar application is hidden away (not shown), however when the user has it shown, the notification does not show.
Is there a way to show the notification while the application is in view?
By default when your application is active, notifications delivered by your app are not shown. To get the expected behaviour, you have to use the user notification center delegate like below :
extension AppController: NSUserNotificationCenterDelegate {
private func setupUserNotificationCenter() {
let nc = NSUserNotificationCenter.defaultUserNotificationCenter()
nc.delegate = self
}
public func userNotificationCenter(center: NSUserNotificationCenter, shouldPresentNotification notification: NSUserNotification) -> Bool {
return true
}
}
I am trying to allow the user to select a .png file to open by clicking file on the menu bar of the application, and then open a Microsoft Word file in the same way.
The problem is it appears that #IBAction func SelectFileToOpen(sender: NSMenuItem) {} cannot access global variables, or set them, and seems completely independent from the rest of the code
here is my code designed to demonstrate how the method can't read global variables:
//
// AppDelegate.swift
// Swift class based
//
// Created by ethan sanford on 2015-01-16.
// Copyright (c) 2015 ethan D sanford. All rights reserved.
//
import Cocoa
#NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {
func applicationDidFinishLaunching(aNotification: NSNotification) {
// Insert code here to initialize your application
}
func applicationWillTerminate(aNotification: NSNotification) {
// Insert code here to tear down your application
}
var myURL=NSURL(fileURLWithPath: "")
#IBAction func btnConcat(sender: NSButton) {
myURL = NSURL(fileURLWithPath: "///Users/ethansanford/Desktop/BigWriting.png")
var say_something = "set URL button clicked"
print(say_something);
print(myURL)
}
#IBAction func SelectFileToOpen(sender: NSMenuItem) {
var say_something = "Menu bar, file-open clicked:"
print(say_something);
print(myURL);
}
#IBAction func communicate(sender: AnyObject) {
var say_something = "communicate button clicked:"
print(say_something);
print(myURL);
}
}
Here is the NSlog produced from this code. Notice that the URL button and the commincate button methods can share the myURL variable, but the file open button seems unable to:
URL button clickedOptional(file://///Users/ethansanford/Desktop/BigWriting.png)
communicate button clicked:Optional(file://///Users/ethansanford/Desktop/BigWriting.png)Menu bar
file-open clicked:nil
communicate button clicked:Optional(file://///Users/ethansanford/Desktop/BigWriting.png)
I need the myURL variable to be able to be used in all three methods. This is necessary for later when I need these methods to communicates so I can take the users selection and display it in an image well. Thanks for any help you can provide. I believe the problem is something specific to the file button in the menu bar.
Can anyone explain to me how to get around this problem?
In your code myURL is an instance variable that will be created within the app delegate. I wonder if you have oversimplified your code sample.
Having said that it should be accessible from the instance methods of the app delegate but having IBAction methods in the AppDelegate rather than in UI code seems like an odd choice (I've never tried it).