iOS: execute code AFTER a particular date

user_14738762 0
Viewed 172

I have some code I want to run after a particular date/time has passed. For example, if I want the code to run 7 days from now and the user opens the app at any time on day 7 or after the code will run but if they open the app before the beginning of day 7 nothing happens. Timers in the main runloop work but only if the app is still running in the background. I need a method that will work even if the user kills the app.

swift events ios
4 Answers

Your best option is to store it as local data Even though you only want the code to run once, the overhead is so low, the "check" will not impact the speed or feel of the application. Also this will allow you to run additional checks .. If someone deletes the app, for instance, and leaves the local storage behind. If they re-install you could theoretically "remember" that the application has been installed, and said code has already run (until the user clears application data)

Something like:

//Globally set key
struct defaultsKeys {
    static let keyDate = "dateKey"
}


// Set the date in local storage
let defaults = UserDefaults.standard
defaults.set("Your Date String", forKey: defaultsKeys.dateKey)


// Get the date from local storage
let defaults = UserDefaults.standard
if let stringDate = defaults.string(forKey: defaultsKeys.dateKey) {
    print(stringDate) 
    //  Do your date comparison here
}

Very few lines of code, and even though the check happens every time the application starts .. The overhead is negligible.

user_15076910

You can either set the date you want your app to "remember" on your local storage or web service. Then, when the user opens your app, compare that date to current device time to determine if you should execute your code.

user_54739790

First, save the current time when you want. You can set the key name however you want.

  UserDefaults.standard.setValue(Date(), forKey: "rememberTime")

And every time I open the app, You compare the current time with the saved time. To do so, I created a function that compares time.

extension Date {
    func timeAgoSince() -> Bool {
        let calendar = Calendar.current
        let unitFlags: NSCalendar.Unit = [.day]
        let components = (calendar as NSCalendar).components(unitFlags, from: self, to: Date(), options: [])
        
        if let day = components.day, day >= 7 {
        // Returns true if more than 7 days have passed.
            return true
        }
        return false
    }
    
}

Recall the previously saved time and use the time comparison function.

let beforeTime: Date = (UserDefaults.standard.object(forKey: "rememberTime") as? Date)!

if beforeTime.timeAgoSince() {
    // more than seven days later
    ...
} else {

    ...
}

If you have a problem, please leave a comment !

user_163473740

You can use the below sample code:

override func viewDidLoad() {
    super.viewDidLoad()
    
    let nextCodeRunDate = Date() + (7 * 24 * 60 * 60) // 7 Days
    
    if let savedDate = UserDefaults.standard.value(forKey: "NEXT_DATE") as? Date {
        
        if Date() > savedDate {
            UserDefaults.standard.setValue(nextCodeRunDate, forKey: "NEXT_DATE")
            runYourCode()
        }
    }else {
        // First time
        UserDefaults.standard.setValue(nextCodeRunDate, forKey: "NEXT_DATE")
        runYourCode()
    }
}

func runYourCode() {
    // Your code
}
user_109741720
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