How to conditionally push local notification in ios app? - ios

Question

i'm working on an ios app which will send notification after the app being sent to the background. I only want the notification to work when the user set a value to true in MainviewController.swift. So I have something like this :
func setDelegateToTrue () {
Appdelegate().setToStart()
}
func setDelegateToFalse () {
Appdelegate().setToEnd()
}
and in my Appdelegate.swift, I have something like this :
var started = false
func applicationDidEnterBackground(application: UIApplication) {
if(started) {
let notification: UILocalNotification = UILocalNotification()
notification.category = "FIRST_CATEGORY"
notification.alertBody = "do not forget your app"
notification.repeatInterval = NSCalendarUnit.Day
notification.timeZone = NSTimeZone.defaultTimeZone()
UIApplication.sharedApplication().scheduleLocalNotification(notification)
started = false
}
}
func setToStart() {
started = true
}
func setToEnd() {
started = false
}
The notification works fine while there is no if statement, however, when I have the if statement and call setDelegateToTrue() in viewdidload, it stopped working. It seems like the boolean value started was to changed after calling setToStart(), but I actually can print things out of setToStart(). Can anyone help me?

Answer 1

Your problem is that you're creating a new instance of AppDelegate when you run AppDelegate().setToStart(). So, when the application delegate it called later it's flag is still set to false, because you set a flag on a different instance (which was immediately destroyed).
To do what you're currently trying to you need to get the delegate from UIApplication (the sharedApplication) and set the flag on that.
Bear this in mind when communication with view controllers and such in OO languages as you always need to get the instance you want to talk to rather than create a new one.

Answer 2

For this behaviour you can make use of NSUserDefault:
Set the value inside the Main ViewController as:
NSUserDefaults.standardUserDefaults().setBool(true, forKey: "shouldSendNotification")
And access this user default in applicationDidEnterBackground of app delegate as follow:
func applicationDidEnterBackground(application: UIApplication) {
let shouldSendNotification = NSUserDefaults.standardUserDefaults().boolForKey("shouldSendNotification")
if shouldSendNotification {
let notification: UILocalNotification = UILocalNotification()
notification.category = "FIRST_CATEGORY"
notification.alertBody = "do not forget your app"
notification.repeatInterval = NSCalendarUnit.Day
notification.timeZone = NSTimeZone.defaultTimeZone()
UIApplication.sharedApplication().scheduleLocalNotification(notification)
NSUserDefaults.standardUserDefaults().setBool(false, forKey: "shouldSendNotification")
}
}

Answer 3

You need to do is
func setDelegateToTrue () {
AppDelegate.sharedAppDelegate().setToStart()
}
func setDelegateToFalse () {
AppDelegate.sharedAppDelegate().setToEnd()
}