I have an app that is constantly reading data from my server and updating the data in the UI. It pulls quite a bit of data, builds some data structures, and then passes the information to the UI. The code below shows how I am collecting the data:
class Server {
private var units: [Unit] = []
...
init {
// I pull data from a firebase realtime database here using the observe method
// which triggers the callback everytime the data changes
// 'data' is a big dictionary of dictionarys which will be sorted into objects
FirebaseDatabaseHandler.getServerInfo(serverAddress: address, callback: { data in
// Because its a lot of data sorting it is hefty so I do this on a background thread
// 'updateQueue' is a single static DispatchQueue that I create in AppDelegate for now
AppDelegate.updateQueue.async {
// here I create an array of data objects using the JSON I pulled from firebase
// then I set the "units" variable of this object and call my update callback
// which triggers a UI update on the main thread
if let unitData = (data?["units"] as? [String:Any]) {
var unitsArray = [Unit]()
for key in unitData.keys {
unitsArray.append(Unit(address: key.base64Decode, data: unitData[key] as! [String:Any]))
}
self.units = unitsArray
self.updateCallback()
}
}
})
}
...
The above code works fine, however the memory is constantly building and not being properly freed, after running for ~10-20 minutes the app builds up to 2GB of memory and crashes from running out of memory.
If I get rid of the AppDelegate.updateQueue.async { } and just let this code run on the main thread, the memory DOES get cleared and there are no crashes, the memory stays around 50-200mb, however if I do this the UI is essentially permanently frozen due to how much processing is happening on the main thread
Ive tried using the debugger to watch the size of my units array and my Server object, but neither grow in size no matter how long the app is running.
Is there anything I can do to debug this, or any reason why the memory wont get cleared when I run it from a background thread?
