I'm just starting to get into app development and have just been learning the uses of Xcode and Objective-C language. Just wondering how an app like snapchat or any other app can send data from one user to another. General answers would suffice just to better my understanding.
How do they test this functionality?
How can they connect peer to peer and send data from one phone to another? Is it all accessed in one database that the app connects to everytime that it pulls down?
When you sign up for an app like this with a registered account is that information stored on the iphone?
Well there are two ways data can be sent to a device. One is the device polls the main server periodically. This can be seen in a pull to refresh scenario. The other is the server can send a push notification to the specific phone and app which causes the data to be received by the device and displayed however the programmer wants. So device to device is essentially one person sending something through a web service call to your server. Your server them packages that information into a Json payload and sends a push notification to the recipient. It seems like its device to device because its so quick, but it requires that you have a server in the middle and of course your server is really sending the push notification to Apple's push server, so there really are two servers involved.
How do they test this functionality?
I would try to do this with real devices, and/or using a network sniffer tool to inspect the send packets.
How can they connect peer to peer and send data from one phone to another? Is it all accessed in one database that the app connects to everytime that it pulls down?
Someones sends you a snap
your app will ask the database every ...min or when you reload if there's something new to load, and gets it from the database if there is something new
When you sign up for an app like this with a registered account is that information stored on the iphone?
Connect to snapchat
get a snap from someone and wait till you can view it
start airplane mode and see if it loads, if it does there are files (temporarily) stored on your iPhone.
Related
I understand the basic concept of having a provider talk to Apple's Push Notification Server which then pushes the notification to the phone. Usually, the provider is an app server running on some machine somewhere completely separate from the app.
However, we don't currently have a separate server, and don't yet need one as everything is currently handled in-app. So, is there any way we can use the app itself as the provider to send a notification to Apple's server and thus to another phone?
Basic concept: we have a game and when a user completes 70% of the level, we'd like to notify his competitors that he's close to finishing the game (or that he has finished at 100%).
If it's possible, are there any security concerns with this approach?
P.S. The app already knows who the competitors are because it displays them in a UITableView.
Technically it's possible. If you include the push certificate with your app, and you have a way to send the device token of each device to all other devices that may need to push to that device, you can push a notification directly from one device to another.
However, in practice, that would require opening and closing many connections to the APNS servers frequently (you'll need a connection for each device, and every time a device loses network connection - which may happen often - you'll have to re-open that connection), which will probably cause Apple to block your app from connecting to their APNS server (since they would interpret it a DDoS attack).
Therefore you should use a server.
For future visitors to this question: we wound up ditching Amazon SNS since we spent nearly 8 hours and couldn't get it working the way we wanted. Instead, we setup Parse Push in rough 15 minutes with exactly what we wanted to do, so I would definitely recommend giving it a look.
i'm writing an app that manage a sqlite database, and i have write a web server, i want the user register in my web server with username and password, i already know how make a request from ios app to server and receive the response, but i want enable also the synchronization of the sqlite database to other device, i now that with core data i can use iCloud synchronization, but for now i prefer use sqlite, and find a way to synchronize it, for example i want create this:
make a change in the sqlite in the iPhone app;
the app send this change to the server for that user;
then the server have to send this update to other device connected at that user;
and now i can't go over, how the server can send this change to the other device? the device has to be always listen to the server? or there is a way to send this update directly to some device and handle it? like an apple push notification?
EDIT: if it's possible use an apple push notification to do this, i doesn't want alert with text sound and badge the user, but send a "silent notification" it's possible?
As a high-level there are a few different ways to approach this, all of which have pros and cons. Two name two examples you can do a polling method, active push or a hybrid approach.
Polling: at some pre-determined interval the app tries to "phone home" and send the delta db changes up to the server. Here you know that your server will be expecting X number of responses in any given interval so you can appropriately gauge your load.
Active Push: The user decides when they want those changes to be transmitted to the server by hitting a "Sync" button. This allows the user to only push data back up to the server when they know there's a change but an over zealous user may make a change, upload, make a change, upload, etc instead of queueing up a bunch of changes and sending them all at once. This may create frequently unneeded server calls.
Hybrid: You setup a polling schedule within the app AND give the user the ability to Sync at-will in the event there is a critical change that needs to be made ASAP.
Regarding the listener side of the equation you face a similar challenge conceptually. If the original user makes 20 changes and presses Sync 20 times do you bombard the second user's device 20 times as well or do you queue those changes up and send them down every 5 minutes (as an example)? Unless you have both devices paired to each other or are connected to the same network AND visible to each other via your app you're going to need to leverage that back-end server. Push notifications can be very useful in this manner but there is extra development and setup overhead to take into account to properly implement them.
To boil this all down I would recommend laying out what YOU want your syncing model to look like before you start marching down a path.
I have a project where I need to be able to send messages from a server running a web service to a specific iDevice. I have no idea how to do this, so any help is very appreciated.
The scenario: I have a web service which receives some message from an iDevice (could also be a Mac or PC, even an Android device). Depending on the content of this message I need to be able to send a message from the web service to another iDevice (I know the IP-address of the specific iDevice). I know how to use URLRequests to send a message from an iDevice to a server and collect the response from the server. In principle I could every 10 seconds send a request to the server asking if the server has any new messages to the sender (the iDevice sending the request), but I am pretty sure this is not the correct way to do it. Is there a way to have an iDevice listen for server communication on a specific port, so that the iDevice only does something active when it receives a message from the server to do something, e.g. display a message in the app listening for the server communication?
I guess I need to use something similar to the technology used for iMessage, but how is this done?
I am using XCode 4.6.2, iOS 6.1.
EDIT: Just to clarify my needs a bit more: The APNS seems to be TOO unreliable (at least that is what I have read in other threads regarding APN) as the web service in some cases can have the need for sending 2 distinct message to an iDevice within 1 minute (in some cases seconds), and as far as I have read in other threads this will simply not be possible because of how Apple's server handles ASPNS.
The app i am developing only needs to receive messages from the server when the app is active - is there any way, not using APNs, to do this, e.g. making the app listen for communication on a specific port?
Your scenario seems pretty similar to APPLE PUSH NOTIFICATIONs (APNs).
Ideally your server side should write a code in such a way that if there is any change on server side & need to be informed to all associated devices.
Then your server should post notification Apple server which will then send a notification to all the associated devices.
Refer this link
You already have but can use this code to identify the iOS/Mac deivce
NSString *identifierString = [[NSUserDefaults standardUserDefaults] objectForKey:#"myID"];
if (!identifierString) {
CFUUIDRef identifier = CFUUIDCreate(NULL);
identifierString = (NSString*)CFUUIDCreateString(NULL, identifier);
[[NSUserDefaults standardUserDefaults] setObject:identifierString forKey:#"myID"];
}
NSLog(#"%#",identifierString);
this code works till the lifetime of the app only.
After some search I have decided not to use the APNS, because it seems like people are having all sort of experience with it. I cannot use APNS because my project needs 100 % reliability and instant communication with the server.
I have decided to use tcp communication since my project only will be used in a local network. This will obviously mean more power consumption on the iDevices, but reliability is more crucial to the project.
I am looking to create a chat app so that two iphones/mobile can chat with each other.
Can someone please head me in the right direction ?
1. Should I try to connect two devices directly using HTTP or TCP
2. Or should the communication pass through a server i.e. one phone sends the message to the server and server then push the message to other phone ?
If you can tell me any libraries/api that I should use, that would be greatly helpful too.
Or should the communication pass through a server i.e. one phone sends the message to
the server and server then push the message to other phone ?
That's the usual approach. A server with a known address is easy to find; mobile phones that move from one network to another and frequently change their addresses are not. Also, you can keep a server running all the time, so that when one device sends a message, the server receives it and stores it until the other device becomes available. If you were to try to run your chat program on the phones all the time, you'd quickly deplete the batteries.
We are building an enterprise class Work Order application where the users will often be in areas with no network coverage. We want to be sure that when they come back into coverage, any work that they have done on locally stored work orders is sent back to the server ASAP. This is easy to do if the user keeps the app running, but in our situation it is very likely that they will switch between apps, and the Work Order app may not be running when they come back into coverage.
We have thought of having the app fire an email to a server side listener when it senses that it is out of coverage. When the device comes back into coverage, the email should get delivered, and the server can send a push notification to the user to open the app. This feels like a bit of a hack... is there a better way to handle this situation?
As you already noticed, push notifications is the way to go, but even with them its not guaranteed that the user will send the data or even open the app.
I would suggest that you make the data itself expire after a limited time and alert the users when they minimize or even close the application.
You can also use local notification to alert about expiration.
So long as this is an enterprise application that doesn't have to be distributed through the App Store, you can abuse the audio background processing mode to keep your application running at all times. All you have to do is play a silent audio file on a loop as if you were a media player. This will keep your application running in the background, where you can retry connections to the server as you'd like.