Fix timers on proximity state change

Author: Atlante45

React/CoreModules/RCTTiming.mm

@@ -148,6 +148,11 @@ - (void)setup
                                                  name:name
                                                object:nil];
   }
+
+  [[NSNotificationCenter defaultCenter] addObserver:self
+                                           selector:@selector(deviceProximityStateDidChange)
+                                               name:UIDeviceProximityStateDidChangeNotification
+                                             object:nil];
 }
 
 - (void)dealloc
@@ -184,6 +189,15 @@ - (void)appDidMoveToForeground
   [self startTimers];
 }
 
+- (void)deviceProximityStateDidChange
+{
+  if ([[UIDevice currentDevice] proximityState]) {
+    [self appDidMoveToBackground];
+  } else {
+    [self appDidMoveToForeground];
+  }
+}
+
 - (void)stopTimers
 {
   if (_inBackground) {