Added usage instructions to README

Author: mariusc

README.md

@@ -4,10 +4,13 @@
 [![Carthage Compatible](https://img.shields.io/badge/Carthage-compatible-4BC51D.svg?style=flat)](https://github.com/Carthage/Carthage)
 [![GitHub license](https://img.shields.io/badge/license-MIT-blue.svg)](https://github.com/nodes-ios/user-manager-type/blob/master/LICENSE)
 
+`UserManagerType` is a protocol that makes it easier to implement a user manager system for your iOS app.
+
+
 ## 📝 Requirements
 
 * iOS 8.0+
-* Swift 2.0+
+* Swift 3.0+
 
 ## 📦 Installation
 
@@ -22,4 +25,80 @@ github "nodes-ios/user-manager-type" ~> 2.0
 > `github "nodes-ios/user-manager-type" == 1.2.0`
 >
 > **Swift 2.2**  
-> `github "nodes-ios/user-manager-type" == 1.1.2`
+> `github "nodes-ios/user-manager-type" == 1.1.2`
+
+ 
+## 💻 Usage
+
+Create a `UserManager` class, that conforms to the `UserManagerType` protocol. Don't forget about the
+
+```swift
+import UserManagerType
+```
+
+Specify the `UserType` typealias to your User class. In the case of this example, the class/struct that we use for a user is called `User`.
+
+```swift
+typealias UserType = User
+```
+
+And that's it. You now have a fully working UserManager, which can store the current user, the current user's token, log out the current user or check if the current user is logged in. 
+
+Have a look at the `UserManagerType`'s interface:
+
+```swift
+///  Get or set the current user object
+public static var currentUser: UserType? { get set }
+
+/// Get or set the token string
+public static var token: String? { get set }
+
+/// Logout current user and set the object with the key `User` to nil and optionally set token to nil.
+public static func logoutCurrentUser(clearToken clear: Bool)
+
+/// Check if someone is logged in
+public static var isLoggedIn: Bool { get }
+```
+## 🔎 Examples
+You probably need to **send an auth token in all your API request headers**. You can get the token like this:
+
+``` swift
+let auth = UserManager.token ?? ""
+```
+
+Anywhere in the code where you need to **access the currently logged in user**, you can do this:
+
+```swift
+if let currentUser = UserManager.currentUser {
+	// do your stuff here
+}
+```
+
+After calling your API's login method, if it succeeded, make sure you **set the token on the `UserManager`**. Setting it only on the `UserManager.currentUser` won't work.
+
+```swift
+ConnectionManager.login(username: username, password: password, completion: { (response) in
+	switch response.result {
+    case .success(let user):
+    UserManager.currentUser = user
+    UserManager.token = user.token
+    // do whatever else needs to be done here
+    
+    case .failure(let error):
+	// handle the error
+})
+```
+
+There are some REST APIs that always return the token on the user object, in all the calls. For those, setting the token separately on the `UserManager` might seem redundant. But other REST APIs only send the token in the response to the login method. If there's a `/me` API call that returns the current user, but without his token, then in the `UserManager`, the `currentUser` would have an empty or nil token (dependin on how you deserialize it). We chose to have the token stored directly on the `UserManager` to accomodate both situations.
+
+To **log out the current user**, you can do this:
+```swift
+UserManager.logoutCurrentUser(clearToken: true)
+```
+This will clear the current user and the token. You will still need to handle the UI for that (i.e. take the user back to the login flow)
+
+## 👥 Credits
+Made with ❤️ at [Nodes](http://nodesagency.com).
+
+## 📄 License
+**UserManagerType** is available under the MIT license. See the [LICENSE](https://github.com/nodes-ios/user-manager-type/blob/master/LICENSE) file for more info.