diff --git a/README.md b/README.md
index 20732ad..453988a 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@
 
 # Updates
 
-To get the iOS7 compatibility, You need to include [NSCalendarExtension](https://github.com/WenchaoD/NSCalendarExtension) into your project.
+[NSCalendarExtension](https://github.com/WenchaoD/NSCalendarExtension) is required to get iOS7 compatibility.
 
 # [中文介绍](http://www.jianshu.com/notebooks/4276521/latest)
 [**QQ交流群: 323861692**](#qq_group)
@@ -128,6 +128,9 @@ calendar.delegate = self
 view.addSubview(calendar)
 self.calendar = calendar
 ```
+
+> **FSCalendar** is fully compatible for Swift3, see `SwiftExample` for more details.
+
 <br/>
 
 ## <a id='adjusts_frame_dynamicly' /></a>Warning 
@@ -157,6 +160,7 @@ self.calendar = calendar
 
 # <a id="pre-knowledge"></a>Pre-knowledge
 ## How to create NSDate object
+
 * By **NSCalendar**.
 
 ```objc
diff --git a/SwiftExample/SwiftExample/ViewController.swift b/SwiftExample/SwiftExample/ViewController.swift
index c2265f6..0efe02e 100644
--- a/SwiftExample/SwiftExample/ViewController.swift
+++ b/SwiftExample/SwiftExample/ViewController.swift
@@ -13,12 +13,12 @@ class ViewController: UIViewController, FSCalendarDataSource, FSCalendarDelegate
     @IBOutlet weak var calendar: FSCalendar!
     @IBOutlet weak var calendarHeightConstraint: NSLayoutConstraint!
     
-    private var formatter: DateFormatter = {
+    private let formatter: DateFormatter = {
         let formatter = DateFormatter()
         formatter.dateFormat = "yyyy/MM/dd"
         return formatter
     }()
-    private var gregorian: NSCalendar! = NSCalendar(calendarIdentifier:NSCalendar.Identifier.gregorian)
+    private let gregorian: NSCalendar! = NSCalendar(calendarIdentifier:NSCalendar.Identifier.gregorian)
     
     let datesWithCat = ["2015/05/05","2015/06/05","2015/07/05","2015/08/05","2015/09/05","2015/10/05","2015/11/05","2015/12/05","2016/01/06",
     "2016/02/06","2016/03/06","2016/04/06","2016/05/06","2016/06/06","2016/07/06"]