I have a Application on a PC which displays time-information for a mp3 song that is played. I now need to display this time information within an iPad App. The counting timers for remaining time, player position and song length must be in sync between iPad an PC.
I thought about using a socket connection (AsyncSocket on iPad) to keep the counters in sync.
Is there a better way doing this? I don't want to run in the wrong direction...
Additional, it should be possible to have more than one iPad showing the Information in future. That's a "nice to have" feature...
I don't need ready to use code snippets, it's more a theoretical question. (if someone has a ready to use code snippet, that's also good for me :-) )
MadMaxApp
i now used the AsyncSocket to solve the requirements. It works perfectly. Don't forget the handling of closing the socket connection if the app goes in background. Depending on the server the app is talking with, not closing the socket can lead to a problem in reconnecting.
Related
I am developing a platform game trying to make it as well for multiplayer using the IOS Multipeer connectivity. I am stuck/confused/do not know what is the best way to send messages between peers (mostly like 4 peers in the game). The game style is like fun run and I have 4 hero running and firing each other and stuff like that. The thing is that keeping the positions of the other players is pushing me crazy!!
Sometimes other players are positioned in the wrong position (keeping in mind all devices are with the same screen size). Is that because of the lag of connectivity. How much information I can send per seconds and what is the best way to manage data transferring?
Any idea/thoughts are appreciated.
The throughput of MPC depends mostly upon the connection. What I've seen as the biggest performance problem is when one of the peers has WiFi disabled. This forces MPC to communicate over bluetooth which is incredibly slow. I've seen it run 20x slower than MPC over Wifi.
You don't need to be connected to a WiFi network. Just enable WiFi on all of the devices and iOS will leverage shared WiFi networks or create its own adhoc network.
The second thing you want to ensure is that your peers don't invite each other. You can only have one inviter in your network. When multiple peers invite and accept connections the MPC network become unstable.
Third thing is sendData:(NSData *)data toPeers:(NSArray *)peerIDs withMode:(MCSessionSendDataMode)mode error:(NSError **)error. If you are broadcasting your packets to all peers in the toPeers: array AND mode is MCSessionSendDataReliable then MPC waits until all of the connected peers ACK the message before moving on to the next packet.
UPDATE: I did some testing with my own app and over WiFi and two devices I can put about 100kbps. I'm using an iPhone 6 Plus and an iPhone 5S.
UPDATE 2: Thinking more about your question, there are a couple things to keep in mind with MPC communications:
Do all of your sendData and didReceiveData calls on a background thread and have that thread update your position data in your model. Tell your viewController that updates are available with a delegate method or notification.
Keep your data packets small, but design them so an update received represents the current state of your player. This allows you to miss an update and not be completely out of sync -- "send player 1 moved to (10, 10)" instead of "player 1 moved by (1, -1)"
Number your packets and use MCSessionSendDataUnreliable. If you get a packet with an earlier number than the last one you processed, throw it away. If you follow the second guideline above, you won't need this packet.
If you follow Dan Loughney's suggestions, I think your best bet in debugging is to log the received coordinates from the other players. That should help you identify whether the problem is due to timing issues, misinterpreted data or something else.
NOTE: This app I am working on is completely for my own usage and will not be on app store so please don't give answers referring that.
I want my app to do some process in background or after termination (double tap the home button and swipe the app from applications multitask) every few minutes. The process is very very light and quick so it won't drain the battery. This process shouldn't require internet connection. I have seen some answers here like and I will explain what are the problems:
VoIP. The problem with VoIP is wither it should be in background to use UIApplication.sharedApplication().setKeepAliveTimeout(..) method which doesn't work when the app is terminated or it should be connected to the internet to establish tcp connection and receive commands from sever and as mentioned before I want it to be internet independent.
Location Services. I found this excellent site with some great articles but the problem is it only works when the mobile phone is moved more than 500 meters. It depends on the location movement so when the phone is staying somewhere there will be no code execution.
Playing an silent audio loop. The problem here is if the user plays another audio (which is completely possible like music or phone call) the app will terminate!
Jailbreak Launch Daemons. I can't require jailbreak so it should be solved with a non-jailbreak solution:(.
I am free to use any kind of private-API's and there will be no restriction for that.
Thanks in advanced
I also faced with such problem, and don't find any solution.
The main problem is if user manually terminated app - in this case you can't do nothing...
Only way is:
a) use Location Services (as you mention)
b) use Push Notifications with background fetch
I am designing an iOS framework to handle multiple BLE devices (all of the same kind). Everything is working very well at the moment, except one thing:
The client wants a list with available devices. But how can I detect when a device, that has been discovered in the past, is not available anymore?
Another problem occurs, when I try to connect to a device that is not available anymore. Documentation says: Connection attempts never time out and
And yes, I never get an error via didFailToConnectPeripheral.
I did some research but couldn't figure out how handle these problems via CoreBluetooth properly. So I developed my own solutions, but I am not sure if that is the right way (or at least a good way, cause there may be several ways to do it).
1. Detecting devices that are not available anymore
I scan with
[_centralManager scanForPeripheralsWithServices:services options:#{CBCentralManagerScanOptionAllowDuplicatesKey: #(TRUE)}];
so I receive advertisments all the time as long as a device is not connected. I check with a timer that the advertisement reoccured in a given time interval (large enough corresponding to the devices ad interval). If the advertisement didn't occur in the interval, I remove the device from the list.
2. Detecting connection timeout
Well, that's a pretty easy one I think. I use my own timeout function and cancel the connection request if the timer expires.
If somebody ever came across these problem, I would be very interested in your opinion and/or your solution of course.
UPDATE 2014-12-17:
In the meantime I worked on my own solution using timers and it seems to work pretty well.
Connection timeout is straight forward. Simply set a timer to 5 seconds or whatever you think is good for you. If the timer expires and the device did not connect, simply cancel the connection and tell the user that there was a problem.
Detecting devices that go out of range was a bit trickier. For every discovered device I start a timer that fires after double the time, the device sends advertisements. If the device does send another advertisement till the timer expires, it probably went out of range or was turned off or connected to another device.
I don't want to answer my own question because I hope that maybe Apple will one day take care of those problems.
The correct way to determine whether a device is available is to store the peripheral identifier value. Before you attempt to reconnect, call retrievePeripheralsWithIdentifiers. However, this still does not guarantee that the device will be in range by the time you attempt to connect!
Connection attempts do not time out at the OS level, and this is explicitly documented.
Some apps may need to use the Core Bluetooth framework to perform
long-term actions in the background. As an example, imagine you are
developing a home security app for an iOS device that communicates
with a door lock (equipped with Bluetooth low energy technology). The
app and the lock interact to automatically lock the door when the user
leaves home and unlock the door when the user returns—all while the
app is in the background. When the user leaves home, the iOS device
may eventually become out of range of the lock, causing the connection
to the lock to be lost. At this point, the app can simply call the
connectPeripheral:options: method of the CBCentralManager class, and
because connection requests do not time out, the iOS device will
reconnect when the user returns home.
I've encountered a pretty large issue and have been trying to find a solution for 2 months now with no luck. I've submitted it as a bug, ( https://bugzilla.xamarin.com/show_bug.cgi?id=4910 ) but was hoping maybe someone here could shed some light on the cause of the problem, or suggest a work-around.
In a nutshell, to encounter the error:
Create a basic .Net socket connection between two devices
Create and initialize a GameKit.GKSession object on a least one device.
What occurs is the transfer of the data on the .NET socket becomes erratic and too slow to be usable. I've performed many tests across different devices (see link below) and it affects all of them (iPad 3 affected the least). I've tested it between an iPhone and a Windows PC and it still occurs. MonoTouch's GameKit code is somehow affecting the Socket code.
As you can see from the spreadsheet, speed drop from a few milliseconds to send 1 MB to several minutes to forever.
As soon as the GameKit.GKSession is set to null, any backedlogged data on the socket flows freely again and the sockets act normally once more.
Sample Windows and iOS/MonoTouch Apps demonstrating problem: https://dl.dropbox.com/u/8617393/SocketBug/SocketBug.zip
Test results across different devices (PDF Spreadsheet):
https://dl.dropbox.com/u/8617393/SocketBug/SocketBugTestResults.pdf
This issue seems so hard even Apple decided to circumvent it: http://developer.apple.com/library/ios/#qa/qa1753/_index.html#//apple_ref/doc/uid/DTS40011315
The revealing sentence is this: "This change was made to reduce interference with Wi-Fi."
To assist with anyone that comes across this problem, the issue only manifests itself when the GKSession.Available is set to true. This is required for the device to be discoverable, but not to maintain a connection. With this in mind, a temporary work-around can be used where the GKSession.Available is only set to true when required, and set to false as soon as the connection has been made.
In my scenario, I have a socket connection to the server on both devices. I use this connection to send a message from device A to device B, asking it to become discoverable via bluetooth for the next 10 seconds. As soon as the message is sent, device A begins looking for device B and connects as soon as it finds it. Once the connection is established (or 10 seconds elapses without a connection), device B turns off discoverability and the socket behaves as normal.
In my circumstances, this is an acceptable (pending no real fix) workaround to the problem.
I have the following problem with GKSessions:
Sometimes there is a huge delay when sending data (3-4 seconds sometimes up to 10 seconds) in a client/server application.
If the server sends let's say 10 packets during the delay, those 10 packets are received all at once on the client. The weird thing is that the server still receives packets from the clients during the delay.
This delay seems to be worse in WiFi networks but also happens in bluetooth networks.
Did anyone else encounter such delay spikes when using gamekit?
What could be the source of this issue?
I've been working a lot with gamekit and gksession. I always use the Peer2Peer mode even though some people discourage it. I never experience any kind of delay like the one you describe.
Do you send with GKSendDataReliable or GKSendDataUnreliable? Try switching to the other and see if it changes anything. If you're using GKSendDataReliable then the sending device will wait for a "Received" message from the receiver before sending the next message. This might be the problem.
On your testing devices: Is anything running which might flood the network?
I was testing a multiplayer gamekit based game, and if I had several active devices then suddenly some would stall completely, and I needed to hard reboot (shut down completely and restart) them to make them work again.
If you keep getting in trouble you might want to try a much more low level api: dns-sd https://developer.apple.com/library/mac/#documentation/Networking/Conceptual/dns_discovery_api/Introduction.html
I hope you make it work, good luck!