ronp001
Subscription after entering background
Hi,
as I can see, redis is loosing connection when app enters background. When app goes back to foreground, I connect clients back. It works for SET and PUBLISH options, but I can't revive the subscription. It looks like we need an UNSUBSCRIBE command enabled. Or you suggest anything else?
Hey - sorry for the delay with this (I'm overloaded with other things at the moment).
Here's how I addressed this in my own app:
// in AppDelegate:
var notificationsConnection: RedisInterface? = nil
func applicationDidBecomeActive(_ application: UIApplication) {
subscribeToNetworkNotifications()
...
}
func applicationWillResignActive(_ application: UIApplication) {
disconnectNotifications()
...
}
func subscribeToNetworkNotifications()
{
guard notificationsConnection == nil else { return }
self.notificationsConnection = RedisInterface(host: ConnectionParams.serverAddress, port: ConnectionParams.serverPort, auth: ConnectionParams.auth)
notificationsConnection!.connect()
notificationsConnection!.subscribe(ConnectionParams.notificationsChannelName, completionHandler: {
success, key, result, cmd in
guard success else {
print("warning: error receiving value on subscription channel \(key)")
return
}
...
})
}
func disconnectNotifications()
{
notificationsConnection?.disconnect()
notificationsConnection = nil
}
BTW - you're more than welcome to add an UNSUBSCRIBE command if you prefer. There are two ways this can be achieved:
Option 1: try using the RedisInterface.generic() function - pass "UNSUBSCRIBE" as the command string. Let me know if you run into any issues with it.
Option 2: add an .unsubscribe function to RedisInterface. Take a look at how the other commands were implemented - it's quite simple. Please open a pull request with your modified code if you do this so I can incorporate into the master branch.
I've done it via GCD. (subscribing multi-channels)
fileprivate func beginRedisSuscribe() {
let riSubscribe = RedisInterface(host: ConnectionParams.serverAddress, port: ConnectionParams.serverPort, auth: ConnectionParams.auth)
riSubscribe.connect()
var subscribeReturnCount = 0
let conqueue = DispatchQueue(label: "queue1", attributes: .concurrent)
conqueue.async {
riSubscribe.subscribe("CN", completionHandler: { success, channel, data, cmd in
// this completion handler should be called several times.
// the first time: to acknowledge that the subscribe operation was registered
// the next two times: in response to publish operations
switch subscribeReturnCount {
case 0:
subscribeReturnCount += 1
break
default:
if let responseData = data?.arrayVal?[2].dataVal {
let json = JSON(data: responseData)
print(json["qLastPrice"].intValue)
print(json["qChangeValue"].doubleValue)
print(json["qTotalQty"].intValue)
print("0-------------")
}
break
}
})
}
conqueue.async {
riSubscribe.subscribe("CL", completionHandler: { success, channel, data, cmd in
// this completion handler should be called several times.
// the first time: to acknowledge that the subscribe operation was registered
// the next two times: in response to publish operations
switch subscribeReturnCount {
case 0:
subscribeReturnCount += 1
break
default:
if let responseData = data?.arrayVal?[2].dataVal {
let json = JSON(data: responseData)
print(json["qLastPrice"].intValue)
print(json["qChangeValue"].doubleValue)
print(json["qTotalQty"].intValue)
print("0-------------")
}
break
}
})
}
}