Update README.md

Author: wenbinf

README.md

@@ -1 +1,114 @@
-# podcast-api-swift
+# Podcast API Swift Library
+
+[![Swift](https://github.com/ListenNotes/podcast-api-swift/actions/workflows/swift.yml/badge.svg)](https://github.com/ListenNotes/podcast-api-swift/actions/workflows/swift.yml)
+
+The Podcast API Swift library provides convenient access to the [Listen Notes Podcast API](https://www.listennotes.com/api/) from
+applications written in the Swift language.
+
+Simple and no-nonsense podcast search & directory API. Search the meta data of all podcasts and episodes by people, places, or topics. It's the same API that powers [the best podcast search engine Listen Notes](https://www.listennotes.com/).
+
+If you have any questions, please contact [[email protected]]([email protected]?subject=Questions+about+the+Swift+SDK+of+Listen+API)
+
+<a href="https://www.listennotes.com/api/"><img src="https://raw.githubusercontent.com/ListenNotes/ListenApiDemo/master/web/src/powered_by_listennotes.png" width="300" /></a>
+
+## Installation
+
+### CocoaPods
+
+[CocoaPods](https://cocoapods.org) is a dependency manager for Cocoa projects. For usage and installation instructions, visit their website. To integrate PodcastAPI into your Xcode project using CocoaPods, specify it in your `Podfile`:
+
+```ruby
+pod 'PodcastAPI', '~> 1.0.1'
+```
+
+### Carthage
+
+[Carthage](https://github.com/Carthage/Carthage) is a decentralized dependency manager that builds your dependencies and provides you with binary frameworks. To integrate PodcastAPI into your Xcode project using Carthage, specify it in your `Cartfile`:
+
+```ogdl
+github "ListenNotes/PodcastAPI" ~> 1.0.1
+```
+
+### Swift Package Manager
+
+The [Swift Package Manager](https://swift.org/package-manager/) is a tool for automating the distribution of Swift code and is integrated into the `swift` compiler.
+
+Once you have your Swift package set up, adding PodcastAPI as a dependency is as easy as adding it to the `dependencies` value of your `Package.swift`.
+
+```swift
+dependencies: [
+    .package(url: "https://github.com/ListenNotes/podcast-api-swift.git", .upToNextMajor(from: "1.0.1"))
+]
+```
+
+### Requirements
+
+- Swift 5+
+
+
+## Usage
+
+The library needs to be configured with your account's API key which is
+available in your [Listen API Dashboard](https://www.listennotes.com/api/dashboard/#apps). Set `apiKey` to its
+value:
+
+```swift
+import Foundation
+import PodcastAPI
+
+let apiKey = ProcessInfo.processInfo.environment["LISTEN_API_KEY", default: ""]
+
+// For command line executables, we have to use synchronous requests, otherwise
+// the program would exit before requests return any response
+let client = PodcastAPI.Client(apiKey: apiKey, synchronousRequest: true)
+
+// By default, we do asynchronous requests.
+// let client = PodcastAPI.Client(apiKey: apiKey)
+
+// All parameters are passed via this Dictionary[String: String]
+// For all parameters, please refer to https://www.listennotes.com/api/docs/
+var parameters: [String: String] = [:]
+
+parameters["q"] = "startup"
+parameters["sort_by_date"] = "1"
+client.search(parameters: parameters) { response in
+    if let error = response.error {
+        switch (error) {
+        case PodcastApiError.apiConnectionError:
+            print("Can't connect to Listen API server")
+        case PodcastApiError.authenticationError:
+            print("wrong api key")
+        default:
+            print("unknown error")
+        }
+    } else {
+        // It's a SwiftyJSON object
+        if let json = response.toJson() {
+            print(json)
+        }
+
+        // Some account stats
+        print(response.getFreeQuota())
+        print(response.getUsage())
+        print(response.getNextBillingDate())
+    }
+}
+```
+
+If `apiKey` is an empty string "", then we'll connect to a [mock server](https://www.listennotes.com/api/tutorials/#faq0) that returns fake data for testing purposes.
+
+
+### Handling errors
+
+Unsuccessful requests return errors.
+
+| Error  | Description |
+| ------------- | ------------- |
+|  authenticationError | wrong api key or your account is suspended  |
+| invalidRequestError  | something wrong on your end (client side errors), e.g., missing required parameters  |
+| tooManyRequestsError  | you are using FREE plan and you exceed the quota limit  |
+| notFoundError  | endpoint not exist, or podcast / episode not exist  |
+| apiConnectionError | failed to connect to Listen API servers | 
+| serverError  | something wrong on our end (unexpected server errors)  |
+
+All errors can be found in [this file](https://github.com/ListenNotes/podcast-api-swift/blob/main/Sources/PodcastAPI/PodcastApiError.swift).