Feature / Check if phone is busy (#39)

* contactIdentifier added to startCall action.

* README.md updated.

* checkIfBusy method added.

* README updated.

* minor fixes.

* checkIfBusy method moved to the bottom of index.js

* minor fix

* check for OS added.

* synced with master

Author: aarkalyk

README.md

@@ -166,6 +166,10 @@ Call when you finish an incoming/outgoing call
 
 Switch the mic on/off
 
+### checkIfBusy
+
+Checks if there are any active calls on the device and returns a promise with a boolean value (`true` if there're active calls, `false` otherwise).
+
 ## Events
 
 ### - didReceiveStartCallAction

index.js

@@ -109,6 +109,12 @@ export default class RNCallKit {
         _RNCallKit.setMutedCall(uuid, muted);
     }
 
+    static checkIfBusy() {
+      return Platform.OS === 'ios'
+        ? _RNCallKit.checkIfBusy()
+        : Promise.reject('RNCallKit.checkIfBusy was called from unsupported OS');
+    };
+
     /*
     static setHeldCall(uuid, onHold) {
         if (Platform.OS !== 'ios') return;

ios/RNCallKit/RNCallKit.m

@@ -83,6 +83,16 @@ - (void)dealloc
     [self.callKitProvider setDelegate:self queue:nil];
 }
 
+RCT_REMAP_METHOD(checkIfBusy,
+                 checkIfBusyWithResolver:(RCTPromiseResolveBlock)resolve
+                 rejecter:(RCTPromiseRejectBlock)reject)
+{
+#ifdef DEBUG
+    NSLog(@"[RNCallKit][checkIfBusy]");
+#endif
+    resolve(@(self.callKitCallController.callObserver.calls.count > 0));
+}
+
 #pragma mark - CXCallController call actions
 
 // Display the incoming call to the user