diff --git a/Source/LBXScanWrapper.swift b/Source/LBXScanWrapper.swift
index 126441c..609bd51 100755
--- a/Source/LBXScanWrapper.swift
+++ b/Source/LBXScanWrapper.swift
@@ -150,14 +150,18 @@ open class LBXScanWrapper: NSObject,AVCaptureMetadataOutputObjectsDelegate {
     func start() {
         if !session.isRunning {
             isNeedScanResult = true
-            session.startRunning()
+            DispatchQueue.global().async {
+                self.session.startRunning()
+            }
         }
     }
     
     func stop() {
         if session.isRunning {
             isNeedScanResult = false
-            session.stopRunning()
+            DispatchQueue.global().async {
+                self.session.stopRunning()
+            }
         }
     }