I made an attendance app in Flutter in which I want to restrict employees to use only network provided time so that employees won't be able to temper the date and time.
Is there any option or solution to implement this in android and iOS as well?
Using this package datetime_settings we will get the settings of Automatic date & time of mobile so when automatic date & time is on mobile will give us an accurate network time otherwise we will show an error to turn on the automatic date & time in settings. That's how I used to restrict users to use only network-provided time.
I'll tell you what worked for me. Hope this can help you. I don't know if it's the most optimized way to do it, but it worked very well for me:
You need to create an internal clock for your app, and from this, use it instead of the DateTime.now() function. For this, you must take the server time when opening the app, and keep it updated with a timer that runs every 1 second.
Please note that the app goes to sleep (or closes) when the device is locked or the app is minimized for a certain amount of time (this depends on the operating system and battery saver settings), thereby stopping the internal clock, and consequently, it is delayed when the app is activated again. In my case, I got around this problem by using a foreground service that I designated to perform this task (I used flutter_foreground_task). Another advantage of using a foreground service, is that the user can close the app and the clock keeps running (and in my case, I also perform other simple tasks periodically).
If the user does not manipulate the system time, the difference should never reach 1 second.
Optionally, you could check when retrieving the server time, the difference with the device time, and if it is greater than a certain gap that you determine, warn the user, so that he can correct it if he prefers, so that he does not see a discrepancy with the time recorded and displayed by the application.
Regards.
Related
Problem: I know about the method applicationSignificantTimeChange to detect manual time change. But the method documentation says:
Examples of significant time changes include the arrival of midnight, an update of the time by a carrier, and the change to daylight savings time. The delegate can implement this method to adjust any object of the application that displays time or is sensitive to time changes.
So it detects not only a manual time change, but arrival of midnight as well. In my application, that will create a problem as the user will see an alertbox:
You have change the time. Please revert back to actual time.
even when he resumes the app after midnight (or may be he minimized the app and went to sleep. Next day he wakes up, resumes the app and surprisingly gets the time change notification).
Question:
How to show the alert only on manual time change and not on arrival of midnight ?
Just use NSSystemClockDidChangeNotification
Apple doc link
I have used a variant of the remote server time check for one or a few years now. It works pretty well, on iOS.
Fetch remote time.
In your time checking class, store the offset between remote time and device time, store that in a simple NSTimeInterval variable.
Now you can get "real time" at any time from your time checking class, because it can take the current device time and just add the stored offset and you will have the real time, all the time.
Whenever the app backgrounds, you will need to delete the stored offset, because the user can be fiddling with the time settings.
For every app foreground event, you will have to perform 3. again. Go get remote time again. Deny any calls to get real time until you have that offset again. Any calls depending on the real time existing will have to fail gracefully in those events where real time has not yet been fetched.
Now the offset you get should/can be compared with the offset you got last time. Decide a threshold, like 15 seconds. If the offset change from last time exceeds that threshold, the user likely changed time manually. This is a useful event for me. Of course even though the user can change the device time I will always have real time handy (most of the time).
Afaik, I always work with UTC time stamps to avoid any locale troubles.
Always its better to check such things with server time.
Follow below steps.
Fetch the server time and convert to current locale.
Check mobile time using current locale.
If they are not same, that means user has changed the time.
Let me know if this is clear or not.
I'm currently working on a new game for iOS using Cocos2D. The game needs to advance states after x amount of time since the first launch. So for example:
State - Time
initial launch
24hrs
48hrs
My first idea was to just get the data and time on first launch and save it to a file. Then I could check it ever now and again to see how much time has passed. The problem with this is I need it to be in realtime so that the changes will take effect immediately once the state is reached. It also needs to continue when the user is not using the app. The functionality I'm looking for is kind of similar to how the iOS strategy games work where you build structures that take x amount of time.
Anyway my question(s) is; is there some sort of library that can accomplish this and how can I get it to continue after the user exits the app?
It can't. There is - apart from kind of misusing video/music playing etc. no way for your app to do work while it is not running.
You have two things you can do to simulate that behavior (and I suppose the strategy games do this, too):
You can calculate at any time while a user is still running your app the points in the future when something should happen (eg a housing structure is finished). When the user leave your app, store these future times as local events - then the user will get notified that something has happened in your game (eg message "The church has been built. Do you want to go to church now?)". Pressing yes will open your app, and you can do whatever is necessary to indeed build the church. So in fact you don't do it at the time when it occurred, but when the user opens your app the next time.
Like 1, but without notification. Just remember when the user leaves the app (eg in your settings, I would use a property list; set it when the app delegate gets the appWillResignActive event), and the next time he starts do whatever would have been done in the meantime - he won't be able to tell the difference :-).
It's all about make believe here :-).
Let's say, Tiny Tower. On this iPhone game, you can have shops in your tower. You can suspend or turn off the iPhone, but when you return to the game, you will be reported about the shop winnings during your time away.
There are also push notifications when a building is complete etc.
I fear I do not understand how that works, exactly. I'm not asking for the exact solution, I just need to know where to begin researching. One idea I had some time ago was like calculate the amount of seconds the user was away (current time minus the time when you left) and then calculate shop processing for every one of these seconds. But I'm not sure of that.
A better way would be to calculate before you close the app.
Figure out what time it is, then calculate when in the future certain tasks will be completed. This way, you can schedule push notifications to the server ahead of time.
If you calculate after you have re-opened the app, and you can't run processes with the app closed, how will it know when to push?
Take a look at this article about push notifications to understand a little bit better how they work.
http://blog.boxedice.com/2009/07/10/how-to-build-an-apple-push-notification-provider-server-tutorial/
For offline games you add temporal logic to your items and recalculate when game is launched. For online games you retrieve game state from the server, which is constantly recalculating for all users, even disconnected ones.
Game most probably does not actually process in the background (most apps are not allowed to do anything while in background). When you relaunch the game, it calculates how much time has passed, and then processes all the events that would have happened in the meantime.
Additionally, as Paul.s mentioned in comments below, as well as other people in other answers have suggested, on iOS4 you can use local push notifications scheduled before close.
It is either server side execution of the game or if it is a game of chance or something like Farmville where it's determined by time duration.
If you were to make a server and/or game like this then you would need to decide which route to take.
If it will be something where the user has good days and sometimes bad days then you'll need a lot more server power. however, if it's something like time based then you would be able to tell the last time they were logged in and the next time that they should be awarded. you can also take this idea and for each variable that you store, you store how long it takes to be complete and the start time. Then you would do a simple If then o see if the item is ready. The same thing can work for a number of visitors. Where you have 10 visitors per item per hour. If you have two items then each hour you will receive 20 visitors.
I would like for my iOS app when it is in background mode to execute at specific intervals some functions
(What I precisely want to do is to check a URL, and indicate its (int) content as a badge.)
However, I don't know how to have the function executed in the background.
Thanks.
Read about Executing Code in the Background. There is a limited set of things you can do in the background, what you describe not among them unfortunately.
I think you have two options to solve this problem each of them has pros and cons.
First, one is background refresh check the link. Have in mind that it is different for ios 13 and above. You need to define background tasks check here. It takes me some time to understand the background tasks but it seems more logical and easy to manage if you have several tasks. Still, you don't have the full control of when this task will be executed. It depends on how much battery, network and so on your task will use every time. The system will choose what is the best time to run it.
There is one more option, to implement a silent push notification check here.
Here you can implement a good push mechanism for updates but you will depend on network and permission for notifications. Also, you will need a backend for this solution.
You need to define what works best for you.
I think the best option is to use the voip background mode. Here you can find all the required information: how to run background process on the iOS using private APIs to sync email items without jailbreaking the phone
https://developer.apple.com/documentation/usernotifications/setting_up_a_remote_notification_server/pushing_background_updates_to_your_app
To update the content frequently when the app is in the background might be difficult, Instead, you can wake the app by pushing a silent notification from backend at regular intervals.
For more information check this article also
https://medium.com/#m.imadali10/ios-silent-push-notifications-84009d57794c
I've decided to integrate OpenFeint into my new game to have achievements and leaderboards.
The game is dynamic and I would like user to be rewarded immediately for some successful results, but as it seems for me, OpenFeint's achievements are a bit sluggish and it shows visual notification only when it receives confirmation from the server.
Is it possible to change something in settings or hack it a little bit to show notification immediately as soon as it checks only local database if the achievement has not been unlocked it?
Not sure if this relates to the Android version of the SDK (which seems even slower), but we couldn't figure out how to make it faster. It was so unacceptably slow that we started developing our own framework that fixes most of open feint's shortcomings and then some. Check out Swarm, it might fit your needs better.
There are several things you can do to more tightly control the timing of these notifications. I'll explain one approach and you can use this as a starting point to explore further on your own. These suggestions apply specifically to iOS apps. One caveat is that these suggestions refer to internal APIs in OFSDK 2.8 for iOS and not ordinarily recommended for high level use and subject to change in future versions.
The first thing I recommend is that you build the sample app with your own product key. Use the standard sample app to experiment before applying the result to your own code.
You are going to get the snappiest response by separating the notification pop-up UI from the process of submitting the achievement. This way you don't have to worry about getting wrapped up in the logic for deciding whether the submission is going just to the local db or is doing the full confirmation on an async network transaction.
See the declaration of "showAchievementNotice" in "OFNotification.h". Performing a search in the sample app, you will see that this is the internal API used for displaying the achievement pop-up when an achievement is earned. It does not actually submit the achievement. You can call this method directly as it is called from "OFAchievementService.mm" to directly control when the message appears. You can then use the following article to disable the pop-up from being called when the actual submission occurs:
http://support.openfeint.com/dev/notification-pop-ups-in-ios/
This gives you complete freedom to call the submission at a later time provided you keep track of the need to do so. For example, you could locally serialize a flag to take care of the actual submission either after the level is done or the next time the app starts up. Don't forget that the user could quit out of a game without cleanly finishing a level.