I'm writing an iPhone app for a client, and they have requested a feature whereby the app "wakes up" at certain times during the day to display a message to the user.
I'm well aware that I can't have the application run in the background and simply move to the foreground at the appropriate time (short of requiring jailbreaking, which isn't really an option for a commercial app). What I'd ideally like would be to simply have the system schedule the application to be run at a particular time of day.
As far as I can tell, the only way to achieve this seems to be to implement push notifications and have a server send the app a message at the appropriate time of day. But this is really ugly and undesirable for several reasons:
It requires a constant internet connection on the user's phone (something that I can't really assume)
It places a large burden on the server in having to keep track of these times (which may be different for each user)
Its just a generally crappy workaround - that's not what push messages are designed for, a dedicated scheduler seems like a much better option.
Does anyone know of a better alternative?
Currently, this is the only option. File a bug with Apple requesting 'local notifications' (a term I've heard their engineers use in relation to this problem.) Ideally, they would work just as push notifications work now, but not require any net connection. Sorry!
Now you can use local notification instead of push notification. Available in iOS 4.0.
Related
I am writing a messaging app in Swift where people can chat similar to how text messages or other popular chat apps work. The supporting API is on AWS, written in C#.
There are some points of interest here:
Hoping to avoid third party stuff like Firebase, etc, but open to listening to advice
Alert notifications are not desired for now - no popups, banners, etc. Simply want to show message bubbles arrive in real time on one viewcontroller - if and only if the person is staring at the message screen. If they're somewhere else on the app, nothing happens.
We don't want to prompt the user to ask them if they're OK with this app sending notifications because we're not sending them banners or anything visual, aside from a new chat arriving. Is that a requirement with APNS? I feel like this means someone can say NO, and then we have no way to update the chat app in real time, which won't fly.
I assume a simple approach would be some sort of timer/loop that runs from the message viewcontroller, where every second or two it hits the API and asks if there are new messages, but that seems inherently wrong to me - the app must be robust, and there could be thousands or hundreds of thousands of people using this - that's a lot of API requests, and in many cases there could be no new messages, thus a wasted call. This is clearly not the way to go, correct?
Question # 1
I was thinking, then, that I should use APNS, however am not sure if it requires you to prompt the user to ask them for permission to receive anything from Apple? Again my concern is the chat bubbles should come in at real time and don't want to give the user the ability to somehow not see these (breaking the app)
If APNS is the way to go, and I must prompt them, then I assume the flow is I will gather my device ids (created in appdelegate, saved in my C# db, and associated to each message thread) and whenever someone types a message, it goes to my API, I save it in the message database table, and then I send out a message to APNS to everyone's device id.
Apple queues this up, and sends to everyone, and if they're on the screen, then the message comes in.
Is this how I should leverage APNS to achieve what I want?
Question # 2 I've seen others recommend using SNS (in conjunction with APNS) however I don't understand why. Doesn't APNS both act as a proper queue, as well as a notification service, thus invalidating the need to use AWS's SNS/SQS at all? It seems redundant to me but maybe I just don't understand the idea behind why you need both technologies.
Appreciate anyone's time in advance if they can shed some light on this for me!
Thanks!
Question 1
Even if you're using WebSockets (As #stevenpcurtis mentioned), you still need to inform user about the fact that user received message when application is in background/suspended. And yes, you must "force" your user to enable notifications for the application and explain why he needs it. Empirically, if user installs messenger, he understands what are notifications used for and why he enables it.
Question 2
From the mobile perspective SNS will still deliver Push notifications when user receives notification while the application is in background or suspended. From the backend perspective you can use SNS.
Conclusion:
From the mobile perspective you have 2 modes:
Application is active - it's generally up to you how to receive messages. (Web Sockets, pushes, e.t.c.)
Application is in the background or is suspended: You need a tool to inform user about changes without having a control on application. This is the job for Push Notification Service. The way you will send pushes from the backend is up to you.
You can also check This question to get some more information.
I am writing an iPhone app, and I have a remote server that will deliver content. I would like to have my app poll the server once per day to see if there is new content, even if it's not running or in the background. I would also like to do this without setting up an APNS. Any advice?
You can't do that, either when your 'not' running or if you are running in the background. The best you could do is to download once per day when your app is first run / pushed to the foreground.
You could use remote notifications to "prompt" the user to bring the app to the foreground so that it could download something?
With the current apple IOS guidelines, that is about the best you can do.
I read that you are trying to avoid using APNS, but I am wondering if you are trying to avoid it for the right reasons, especially when it is designed to efficiently solve the scenario you are describing. I've seen many developers seek alternative solutions to APNS simply because the technology appeared to be complex to use after looking at Apple's documentation. The online documentation does go into a lot of details, right down to the binary protocol level.
But just to be sure you know, there are open-source libraries whose only purpose is to shield you from all these technical details. Some libraries are more complex than others, but some are remarkably user-friendly. If you have not done so already, you might like to take a look at JavaPNS and other similar projects.
What are the key concepts that a developer should know when building an iPhone application that takes advantage of push notifications?
Number one most important thing, I think, is that your app can't depend on them. It's probably best to regard them as a nice thing for your user, rather than a part of your app's infrastructure. In particular:
Apple doesn't guarantee delivery of the notices. Yes, their infrastructure is pretty good, but there's no promise.
Only one alert can be up on the device at a time, and there's no log. So if the user has a bunch of push-enabled apps, you can't depend on them seeing your alerts.
The only way that your app knows about a notice is if the user chooses to run it in response to an alert.
The user can always turn push notices off, for your app, or for the whole device.
All of that also means: you can't cheat the "no background processes" restriction with the Push Notification Service. :-)
I am trying to determine feasibility of certain features required in a (potential) project. I am not (yet) looking for a how-to, just a can-do. I apologize for any vagueness and ignorance: the former due to an NDA that makes Apple's NDA look like GPL, and the latter due to the fact that I have no iPhone or MAC experience.
I do have a solid understanding of objective-c and interface builder (going back to NextStep) and some PDA development experience, so I'll probably understand the answers, even if my questions are naive. I have done a bit of browsing, so I know some buzzwords.
I can't go into detail about the actual project, but I have come up with a lame analogy.
a large number of users in the same room are asked to complete task(s) in the app (say a puzzle)
they are under supervision, but the monitor cannot watch them all closely
they are not allowed to leave the application until done.
they cannot send/receive phone calls or messages during the task.
the monitor receives notification of various steps during the task
the monitor is notified when the task is completed, or the app is exited
the app sends a heartbeat, so the monitor also knows if signal is lost
Jailbreak is not an option.
The app should also work on iPod Touch.
So the things I need to do that seem dicey to me are
can I turn off (or require the user to turn off) phone and sms but still be able send http to my server
can I prevent an app from being switched out (even if, say an alarm app triggers or the phone rings).
failing prevention, can I at least detect any of these events and notify my server.
failing notification, can I record the event for the monitor to check later.
The user will be aware (and in fact welcome) these restrictions. It's a trust issue - the user must not seek help or use a helper app to solve the puzzle, and wants the monitor (and other contestants) to know that he did not. It's feasible for the user to click on an "OK, I understand and approve" screen at the beginning, but not for each communication to the server.
The app would only communicate with a central server (run by my company) - the monitor would not be able to buy the server software, and the url's of the server would not be user (or monitor) modifiable.
Hey! This looks like an app for taking exams. Not what I am doing, but that would be cool too!
EDIT --
I changed the title and am adding a few more parts to the question, based in part on mmc's answer. The App may run in an offline mode that would have to do the following:
So using the exam analogy, the user off line experience would be something like this
Launch App
App download test questions, registers start time, etc.
Turn off phone (if app can't do it by itself)
Disable any app that might interrupt my App (can app do this?)
Resume and Take Test
Indicate test done (or finish last problem).
Turn on phone (if app can't) and restart App (if needed).
App uploads test results and log of any interruptions.
So the question becomes
Am I sure that I at least get to log any interruption I can't prevent
can I know the cause of the interruption (phone answered, alarm launch, user initiated)?
can the user be prevented from modifying the log
can I know what other Apps are running when I start? (to guard against a daemon that occasionally displays a hint or something.
I would still like to run with real time uploads, so a few other ideas come to mind.
If I can reliably detect and record that the phone or another app was used, that might be almost as good as preventing it.
Can the user prevent the phone from ringing even if it's on (eg. call forward + ringer off)
Can my app know if the ringer is off
Same question for sms messaging
If I can't block it, can the user just ignore (silent) call or message and not leave my App. Would my app know that?
Sounds like you might be better off doing away with the phone, and making it exclusive to the iPod Touch.
You've nailed your trouble spots.
There is no way to disable phone functionality, and at the same time maintain network functionality of any type (3G, WiFi, or bluetooth) If you disable the phone operations with Airplane mode, all of them are disabled.
There is no way to prevent the Home button from returning you to Springboard
You can notify a server of a premature app interruption (there is an applicationWillTerminate: method on your app delegate) but is not reliable. If the operation takes too long, your app will be forcibly terminated.
You could write to the local file system that a premature interruption happened, and this would be far more reliable, as this operation would be much faster.
I want to write a perlscript on my iPhone that is able to give me a heads up at certain points so I'm wondering how I would go about doing that.
Is there a way to get a message through the gui from a script running in the background? I've been looking without much luck. I had a thought about inserting a fake sms into the sqlite db as a last resort but it seems somewhat unlikely that it would work.
It would be nice to be able to make a push notification style popup appear but that might too much to ask.
Any ideas?
For reasons of security and stability, Apple does not allow scripting languages on the iPhone. You can run them on a jailbroken phone but I'm given to understand it's a hassle.
From the Apple Push Notification Programming Guide:
Note: On a desktop system, a
background process is often the means
whereby users are informed of
downloadable data for an application
that currently isn’t running. But on a
device such as the iPhone, background
applications are, for performance and
security reasons, prohibited. Only one
application may be executing at a
time.
The iPhone is a secure and reliable phone first and a computer second. Computing is sacrificed to ensure a reliable phone.
I found a solution I liked so I decided to share it. I found an app for jailbroken iPhones called GriP - Growl for iPhone. Which changes the way push notifications and other messages are handled. It also makes it possible to send messages from the command line via something along the lines of:
/usr/bin/GriP -t "Title" -d "Description"
It has worked great so far.
Thank you for your help TechZen and molecules.
Do you want information from your phone itself or from an outside source? If you want information from an outside source, you could set up a Perl script on a computer to e-mail yourself notifications (see Sending Email with Perl Best Practice).