Update README

README.md

@@ -1,11 +1,9 @@
 # ![Logo](https://github.com/kaishin/Gifu/raw/master/header.gif)
 
-[![GitHub release](https://img.shields.io/github/release/kaishin/Gifu.svg)](https://github.com/kaishin/Gifu/releases/latest) ![Bitrise](https://www.bitrise.io/app/a0eae2c9b6aa754c.svg?token=dDlRyPi2aOlZnvbl4kL8Kw&branch=master) [![Carthage compatible](https://img.shields.io/badge/Carthage-compatible-4BC51D.svg?style=flat)](https://github.com/Carthage/Carthage) [![Join the chat at https://gitter.im/kaishin/gifu](https://badges.gitter.im/kaishin/gifu.svg)](https://gitter.im/kaishin/gifu) ![Swift 3.0.x](https://img.shields.io/badge/Swift-3.0.x-orange.svg) ![platforms](https://img.shields.io/badge/platforms-iOS-lightgrey.svg)
+[![GitHub release](https://img.shields.io/github/release/kaishin/Gifu.svg)](https://github.com/kaishin/Gifu/releases/latest) ![Bitrise](https://www.bitrise.io/app/a0eae2c9b6aa754c.svg?token=dDlRyPi2aOlZnvbl4kL8Kw&branch=master) [![Carthage compatible](https://img.shields.io/badge/Carthage-compatible-4BC51D.svg?style=flat)](https://github.com/Carthage/Carthage) ![Swift 4.0](https://img.shields.io/badge/Swift-4.0-orange.svg) ![platforms](https://img.shields.io/badge/platforms-iOS-lightgrey.svg)
 
 Gifu adds protocol-based, performance-aware animated GIF support to UIKit. (It's also a [prefecture in Japan](https://goo.gl/maps/CCeAc)).
 
-⚠ The `master` branch works with Xcode 9 and iOS 11, which are both in beta. Use `v2.0` for the stable version.
-
 ## Install
 
 ### [Carthage](https://github.com/Carthage/Carthage)
@@ -119,7 +117,9 @@ The simplest way to get started is initializing a `GIFAnimatable` class in code
 
 ~~~swift
 let imageView = GIFImageView(frame: CGRect(x: 0, y: 0, width: 200, height: 100))
-imageView.animate(withGIFNamed: "mugen")
+imageView.animate(withGIFNamed: "mugen") {
+  print("It's animating!")
+}
 ~~~
 
 You can also prepare for the animation when the view loads and only start animating after a user interaction.
@@ -129,7 +129,9 @@ You can also prepare for the animation when the view loads and only start animat
 
 override func viewDidLoad() {
   super.viewDidLoad()
-  imageView.prepareForAnimation(withGIFNamed: "mugen")
+  imageView.prepareForAnimation(withGIFNamed: "mugen") {
+    print("Ready to animate!")
+  }
 }
 
 @IBAction func toggleAnimation(_ sender: AnyObject) {
@@ -161,8 +163,8 @@ See the [full API documentation](http://kaishin.github.io/Gifu/).
 ## Compatibility
 
 - iOS 9.0+
-- Swift 3.0
-- Xcode 8.0
+- Swift 4.0
+- Xcode 9.0
 
 ## License