Cancel timers before making nil

Author: dsmurfin

Sources/sACNKit/Receiver/sACNDiscoveryReceiver.swift

@@ -306,6 +306,7 @@ public class sACNDiscoveryReceiver {
 
     /// Stops the main heartbeat timer.
     private func stopHeartbeat() {
+        heartbeatTimer?.cancel()
         heartbeatTimer = nil
     }
 

Sources/sACNKit/Receiver/sACNReceiverRaw.swift

@@ -237,6 +237,7 @@ public class sACNReceiverRaw {
             guard _isListening else { return }
             self._isListening = false
 
+            sampleTimer?.cancel()
             sampleTimer = nil
             stopHeartbeat()
 
@@ -390,6 +391,7 @@ public class sACNReceiverRaw {
 
     /// Stops the main heartbeat timer.
     private func stopHeartbeat() {
+        heartbeatTimer?.cancel()
         heartbeatTimer = nil
     }
 
@@ -437,6 +439,7 @@ public class sACNReceiverRaw {
 
                 self.beginSamplingPeriod(notify: false)
             } else {
+                self.sampleTimer?.cancel()
                 self.sampleTimer = nil
 
                 // notify sampling has ended

Sources/sACNKit/Source/sACNSource.swift

@@ -547,7 +547,10 @@ final public class sACNSource {
 
     /// Stops this source's universe discovery heartbeat.
     private func stopUniverseDiscovery() {
-        timerQueue.sync { universeDiscoveryTimer = nil }
+        timerQueue.sync {
+            universeDiscoveryTimer?.cancel()
+            universeDiscoveryTimer = nil
+        }
     }
 
     /// Starts this source's data transmission heartbeat.
@@ -666,7 +669,10 @@ private extension sACNSource {
             // termination of all universes to be removed is complete
             if self.shouldTerminate {
                 // the source should terminate
-                timerQueue.sync { dataTransmitTimer = nil }
+                timerQueue.sync {
+                    dataTransmitTimer?.cancel()
+                    dataTransmitTimer = nil
+                }
 
                 sockets.forEach { _, socket in
                     socket.stopListening()