Behold. I am trying to create an IOS app with swift 4.2, which, according to my client, has to sound an alarm, but it can only be stopped with a QR code. Therefore, what I will need will be a timer that works in the background, checking the time every second, because something else, the user could stop it, without the QR code. The only thing I've found for that is the Background Fetch, but can it work with 1 second checks every time?
Does anyone have a better idea?
Cheers
This is my source code for now
App delegate:
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
UIApplication.shared.setMinimumBackgroundFetchInterval(2.0)
}
//ini----------------------------background task
func application(_ application: UIApplication, performFetchWithCompletionHandler completionHandler: #escaping (UIBackgroundFetchResult) -> Void) {
// fetch data from internet now
let time:TimerNow = TimerNow();
let hours = preferences.string(forKey: "hours");
let minutes = preferences.string(forKey: "minutes");
if((hours == time.getHours())&&(minutes == time.getMinutes())){
lem.onPlayCommand();
}
completionHandler(.newData)
}
//fin ---------------------------background task
I think you should use local notifications instead. It will be fired when you want to notify about the elapsed time. You could cancel it whenever and with any condition you want.
IMO timer and background fetching is not suitable for that situation.
Related
I am trying to implement the new iOS 13 background tasks functionality with a new app that is utilizing Scenes (also new). There are not a lot of examples, but the ones I have found were not using SceneDelegates, instead all the logic was contained in the AppDelegate. This causes issues since the event for the app going into the background is now raised in the SceneDelegate, not the AppDelegate.
This method does not fire in AppDelegate when using scenes
func applicationDidEnterBackground(_ application: UIApplication) {
}
This method does fire in SceneDelegate
func sceneDidEnterBackground(_ scene: UIScene) {
}
I am not able to find a corresponding SceneDelegate method for the following method in AppDelegate where all the examples show BGTaskScheduler registering tasks
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
BGTaskScheduler.shared.register(forTaskWithIdentifier: "UNIQUE_ID", using: DispatchQueue.global()) { task in
refreshMethod(task: task as! BGAppRefreshTask)
}
}
My question is whether there is some event in the SceneDelegate where I can register the task and if not what is the recommended pattern to follow for scene based apps.
AppDelegate.didFinishLaunchingWithOptions is still called at app launch, even when you have a SceneDelegate. So you should continue to register your background tasks in that method.
I'm looking at apple documentation, but do not see the function call to tell me how much time I have left for background fetch execution.
How do I check the time budget I have left for background fetch?
//request refresh every 90 minutes:
UIApplication.shared.setMinimumBackgroundFetchInterval(90 * 60)
func application(_ application: UIApplication,
performFetchWithCompletionHandler completionHandler:
#escaping (UIBackgroundFetchResult) -> Void) {
//how to check if I still have background execution time remaining?
}
I need a simple method of counting the seconds between the last time i closed an app and i opened it....is there any simple way to do so?
Nothing else in the code needs changing, only number of seconds between "lastAppClosingTime' and "app Launched is needed.
I am thinking about using the 'timeserving' but I', unsure if it'll be efficient
I have a countdown in my app, requiring the user to press a button 10 minutes before the end, however i have no idea how to make the app calculate whenever the user failed the LAST check or not
You can store time when you app is to be terminated, one once the app is launched compare the last close date with current time, as such (goes to AppDelegate.swift):
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
if let date = UserDefaults.standard.object(forKey: "TerminatedAt") as? Date {
let components = Calendar.current.dateComponents([.second], from: date, to: Date())
let numberOfSecondsSinceAppClosed = components.second ?? 0
}
return true
}
func applicationWillTerminate(_ application: UIApplication) {
UserDefaults.standard.set(Date(), forKey: "TerminatedAt")
UserDefaults.standard.synchronize()
}
I am trying to implement Apple CallKit in my VoIP application. I am using Xcode 9.2, Swift 4.0.3, iOS 10.3. Problem is I do not know how exactly to do this. I have tried to search for tutorial in Web, but I failed to find tutorial based on real system. They all using fake systems, only simulate calls! I have a class which rules with someone third person library which is responsible for the calls. So, if I have incoming call happens, some event goes through observer. Like this:
NotificationCenter.default.addObserver(forName: Notification.Name(rawValue: Notifications.Name.transMessage.rawValue), object: nil, queue: nil) { notification in
self.handleLibtransEvents()
}
where self.handleLibtransEvents is private function calling calls.
Plus, I have installed working PUSH Notification system in AppDelegate.swift. Like this:
func application(_ application: UIApplication, didFailToRegisterForRemoteNotificationsWithError error: Error) {
print("NOTIFICATION ERROR: \(error)")
}
func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
let pushToken = deviceToken.reduce("", {$0 + String(format: "%02X", $1)}).lowercased()
print("pushToken: \(pushToken)")
}
func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable: Any], fetchCompletionHandler completionHandler: #escaping (UIBackgroundFetchResult) -> Void) {
if UIApplication.shared.applicationState != UIApplicationState.active {
// PUSH: Incoming call event!
}
}
So there are two places, I can catch incoming call but I have not any idea how to catch real call through Apple CallKit. I will be thankful for any help, advice, call example. Thanks!
P. S. I have installed all settings correctly.
CallKit is basically a framework to show up a Call UI when ever you receive a voip call or make a new call, So it will do nothing if you pass it a number n assume it will make call, Keep it in mind its only to show a UI for receive call & make call.
To make calls n receive calls you will need 3rd party services like Sinch and many other.
I'm trying to make my app download images in background. But when I press [Home] button, the app stop download. Is there any way to make it continue download even when I use another app? I have seen some apps can do like that but I don't know how.
This is what I've tried so far.
//
// AppDelegate.swift
// Swift-TableView-Example
//
// Created by Bilal ARSLAN on 11/10/14.
// Copyright (c) 2014 Bilal ARSLAN. All rights reserved.
//
import UIKit
import WebKit
protocol DownloadInBackgroundDelegate {
func downloadInBackgroundDidFinish(chapterid:Int, chaptername:String, storyid:Int, progressPercent:Float)
}
#UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
var shareCache = NSURLCache()
var downloadDelegate:DownloadInBackgroundDelegate? = nil
func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
// Override point for customization after application launch.
var navigationBarAppearace = UINavigationBar.appearance()
application.setStatusBarOrientation(UIInterfaceOrientation.PortraitUpsideDown, animated: false)
self.startDownload()
return true
}
func application(application: UIApplication,
didReceiveRemoteNotification userInfo: [NSObject : AnyObject],
fetchCompletionHandler completionHandler: (UIBackgroundFetchResult) -> Void) {
}
func applicationWillResignActive(application: UIApplication) {
// Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
// Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}
func applicationDidEnterBackground(application: UIApplication) {
// Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
// If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}
func applicationWillEnterForeground(application: UIApplication) {
// Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
}
func applicationDidBecomeActive(application: UIApplication) {
// Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
FBAppEvents.activateApp()
}
func applicationWillTerminate(application: UIApplication) {
// Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
}
func application(application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: NSData) {
}
func application(application: UIApplication, didFailToRegisterForRemoteNotificationsWithError error: NSError) {
}
func application(application: UIApplication, didReceiveRemoteNotification userInfo: [NSObject : AnyObject]) {
}
func applicationDidReceiveMemoryWarning(application: UIApplication) {
NSURLCache.sharedURLCache().removeAllCachedResponses()
}
func application(application: UIApplication, willChangeStatusBarOrientation newStatusBarOrientation: UIInterfaceOrientation, duration: NSTimeInterval) {
application.windows
}
func startDownload(){
var filesPath = [String]()
filesPath.append("https://developer.apple.com/library/ios/documentation/iphone/conceptual/iphoneosprogrammingguide/iphoneappprogrammingguide.pdf")
filesPath.append("https://developer.apple.com/library/ios/documentation/UserExperience/Conceptual/MobileHIG/MobileHIG.pdf")
filesPath.append("https://developer.apple.com/library/ios/documentation/NetworkingInternetWeb/Conceptual/NetworkingOverview/NetworkingOverview.pdf")
filesPath.append("https://developer.apple.com/library/ios/documentation/AudioVideo/Conceptual/AVFoundationPG/AVFoundationPG.pdf")
filesPath.append("http://manuals.info.apple.com/MANUALS/1000/MA1565/en_US/iphone_user_guide.pdf")
downloadFiles(0, filesPath: filesPath)
}
func downloadFiles(index: Int, filesPath: [String]) -> Void {
var imgURL: NSURL = NSURL(string: filesPath[index].stringByTrimmingCharactersInSet(.whitespaceAndNewlineCharacterSet()).stringByAddingPercentEscapesUsingEncoding(NSUTF8StringEncoding)!)!
let request: NSURLRequest = NSURLRequest(URL: imgURL)
NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue.mainQueue(), completionHandler: {(response: NSURLResponse!,data: NSData!,error: NSError!) -> Void in
var fileCacheName = String(format: "%04d", index)
dispatch_async(dispatch_get_main_queue(), {
var fileExt = (data != nil && error == nil) ? Utility.checkImageType(data) : ""
let paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0] as! String
let imagePath = paths.stringByAppendingPathComponent("\(fileCacheName).png")
if data.writeToFile(imagePath, atomically: false)
{
println("saved")
}
if index < filesPath.count - 1
{
var nextIndex:Int = index + 1
self.downloadFiles(nextIndex, filesPath: filesPath)
}
})
})
}
}
Answer
Based on the comment below, I found this thread : objective c - Proper use of beginBackgroundTaskWithExpirationHandler . I can solve my problem with it.
For downloading and storing of the images, instead of writing the logic yourself, I suggest you use some well known libraries, like:
https://github.com/Haneke/Haneke
https://github.com/rs/SDWebImage
Reason behind that is those libraries are well tested, quite robust and mainly very easy to use for basic tasks.
Now for the background download, there is beginBackgroundTaskWithExpirationHandler: that is specifically designed to do that. When you use it, you will get few more minutes to execute whatever you need (after that limit, your application will get terminated no matter what).
You can write following methods:
func beginBackgroundTask() -> UIBackgroundTaskIdentifier {
return UIApplication.sharedApplication().beginBackgroundTaskWithExpirationHandler({})
}
func endBackgroundTask(taskID: UIBackgroundTaskIdentifier) {
UIApplication.sharedApplication().endBackgroundTask(taskID)
}
When you want to use it, you just simple begin / end the task when starting / finishing the download call:
// Start task
let task = self.beginBackgroundTask()
// Do whatever you need
self.someBackgroundTask()
// End task
self.endBackgroundTask(task)
Hope it helps!
Use beginBackgroundTaskWithExpirationHandler: from the UIApplication to start a background task when the app enters the background
See Apple's document on multitasking background execution for details. See download in background in iphone its a similar question.