chore(phone-as-device): app-481 get private key from Keychain

Author: alessioemireni

ios/MqttClient.swift

@@ -55,7 +55,7 @@ class MqttClient : RCTEventEmitter {
         self.hasListeners = false
     }
 
-    func loadPrivateKeyFromKeychain(keyTag: String, block: SecKeyPerformBlock){
+    func loadPrivateKeyFromKeychain(keyTag: String, reject: RCTPromiseRejectBlock, block: SecKeyPerformBlock){
         var query: [String: AnyObject] = [
             String(kSecClass)             : kSecClassKey,
             String(kSecAttrApplicationTag): keyTag as AnyObject,
@@ -76,6 +76,8 @@ class MqttClient : RCTEventEmitter {
         if status == errSecSuccess {
             print("\(keyTag) Key existed!")
             block((result as! SecKey?)!)
+        } else {
+            reject("LOAD_KEY_ERROR", "Key does not exist", nil)
         }
     }
 
@@ -161,7 +163,7 @@ class MqttClient : RCTEventEmitter {
             resolve(nil)
         }
 
-        self.loadPrivateKeyFromKeychain(keyTag: keyTag, block: block)
+        self.loadPrivateKeyFromKeychain(keyTag: keyTag, reject: reject, block: block)
     }
 
     @objc(loadIdentity:resolve:reject:)