replace var to let

ios/Classes/QRView.swift

@@ -44,7 +44,7 @@ public class QRView:NSObject,FlutterPlatformView {
             [weak self] (call: FlutterMethodCall, result: FlutterResult) -> Void in
             switch(call.method){
                 case "setDimensions":
-                    var arguments = call.arguments as! Dictionary<String, Double>
+                    let arguments = call.arguments as! Dictionary<String, Double>
                     self?.setDimensions(width: arguments["width"] ?? 0,height: arguments["height"] ?? 0)
                 case "flipCamera":
                     self?.flipCamera()

ios/Classes/QRViewFactory.swift

@@ -17,7 +17,7 @@ public class QRViewFactory: NSObject, FlutterPlatformViewFactory {
     }
     
     public func create(withFrame frame: CGRect, viewIdentifier viewId: Int64, arguments args: Any?) -> FlutterPlatformView {
-        var dictionary =  args as! Dictionary<String, Double>
+        let dictionary =  args as! Dictionary<String, Double>
         return QRView(withFrame: CGRect(x: 0, y: 0, width: dictionary["width"] ?? 0, height: dictionary["height"] ?? 0), withRegistrar: registrar!,withId: viewId)
     }