前言
了解本文之前需要准备JS和WebView的一些基础知识，需要知道JS的基本语法和WebView调用JS的常用接口。
iOS实现JS和Native交互的WebView有UIWebView和WKWebView。通过KVC拿到UIWebView的JSContext，通过JSContext实现交互。
WKWebView有了新特性MessageHandler来实现JS调用原生方法。从实现思路是来讲，UIWebView和WKWebView是一样的。
所以，本文只介绍WKWebView上JS和Native的交互思路，UIWebView有需求的可以模仿实现。
JS和Native交互常用的场景
常用的分为下面几种场景：
H5获取Native用户信息（这种比较简单，只需要Native注入JS就行了，思路有三种下面介绍）
H5传递信息给Native，调用Native分享（这种属于JS调用Native）
Native告诉H5分享结果（这种属于Native调用JS）
下面一一介绍，实现如下：
H5获取Native用户信息
现有用户信息格式如下，需要注入到JS，供H5调用：
let userInfo = ["name": "wb", "sex": "male", "phone": "12333434"]
注入JS变量
Native注入JS变量实现如下
let userContent = WKUserContentController.init()
let userInfo = ["name": "wb", "sex": "male", "phone": "12333434"]
for key in userInfo.keys {
let script = WKUserScript.init(source: "var \(key) = \"\(userInfo[key]!)\"", injectionTime: .atDocumentStart, forMainFrameOnly: true)
userContent.addUserScript(script)
}
let config = WKWebViewConfiguration.init()
config.userContentController = userContent
let wkWebView: WKWebView = WKWebView.init(frame: UIScreen.main.bounds, configuration: config)
wkWebView.navigationDelegate = self
wkWebView.uiDelegate = self
view.addSubview(wkWebView)
view.insertSubview(wkWebView, at: 0)
wkWebView.load(URLRequest.init(url: URL.init(string: "http://192.168.2.1/js.html")!))
通过遍历userInfo的keys，把key作为变量，value作为String值，注入到JS上下文中。
在H5中实现调用如下
js Bridge demo
js demo test
注入JS对象
Native注入JS对象实现如下
let userContent = WKUserContentController.init()
let userInfo = ["name": "wb", "sex": "male", "phone": "12333434"]
let jsonData = try? JSONSerialization.data(withJSONObject: userInfo, options: .prettyPrinted)
let jsonText = String.init(data: jsonData!, encoding: String.Encoding.utf8)
let script = WKUserScript.init(source: "var userInfo = \(jsonText!)", injectionTime: .atDocumentStart, forMainFrameOnly: true)
userContent.addUserScript(script)
let config = WKWebViewConfiguration.init()
config.userContentController = userContent
let wkWebView: WKWebView = WKWebView.init(frame: UIScreen.main.bounds, configuration: config)
wkWebView.navigationDelegate = self
wkWebView.uiDelegate = self
view.addSubview(wkWebView)
view.insertSubview(wkWebView, at: 0)
wkWebView.load(URLRequest.init(url: URL.init(string: "http://192.168.2.1/js.html")!))
通过把userInfo字典转化成json，作为对象赋值给userInfo，注入JS上下文中。
在H5中实现调用如下
js Bridge demo
js demo test
注入JS函数
Native注入JS函数实现如下
let userContent = WKUserContentController.init()
let userInfo = ["name": "wb", "sex": "male", "phone": "12333434"]
let jsonData = try? JSONSerialization.data(withJSONObject: userInfo, options: .prettyPrinted)
let jsonText = String.init(data: jsonData!, encoding: String.Encoding.utf8)
let script = WKUserScript.init(source: "var iOSApp = {\"getUserInfo\":function(){return \(jsonText!)}}", injectionTime: .atDocumentStart, forMainFrameOnly: true)
userContent.addUserScript(script)
let config = WKWebViewConfiguration.init()
config.userContentController = userContent
let wkWebView: WKWebView = WKWebView.init(frame: UIScreen.main.bounds, configuration: config)
wkWebView.navigationDelegate = self
wkWebView.uiDelegate = self
view.addSubview(wkWebView)
view.insertSubview(wkWebView, at: 0)
wkWebView.load(URLRequest.init(url: URL.init(string: "http://192.168.2.1/js.html")!))
通过封装getUserInfo匿名函数，执行函数return我们的对象，生成全局对象iOSApp，调用iOSApp.getUserInfo()。
这样写的好处是，我们的H5在调用函数的时候，可以很容易知道哪些是原生注入，防止和本地造成冲突，便于理解。
在H5中实现调用如下
js Bridge demo
js demo test
以上讲了三种方式实现用户信息的传递，都是通过WKUserContentController注入JS实现的，实际上我也可以通过WebView的evaluateJavaScript方法实现注入。
evaluateJavaScript实现注入
同样的WebView的调用H5，提供了evaluateJavaScript接口，此接口既可以执行JS函数回调结果，也可以注入JS。
下面使用接口实现JS函数的注入
let userContent = WKUserContentController.init()
let config = WKWebViewConfiguration.init()
config.userContentController = userContent
let wkWebView: WKWebView = WKWebView.init(frame: UIScreen.main.bounds, configuration: config)
wkWebView.navigationDelegate = self
wkWebView.uiDelegate = self
view.addSubview(wkWebView)
view.insertSubview(wkWebView, at: 0)
wkWebView.load(URLRequest.init(url: URL.init(string: "http://192.168.2.1/js.html")!))
...
//代理方法加载完成
func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
let userInfo = ["name": "wb", "sex": "male", "phone": "12333434"]
let jsonData = try? JSONSerialization.data(withJSONObject: userInfo, options: .prettyPrinted)
let jsonText = String.init(data: jsonData!, encoding: String.Encoding.utf8)
webView.evaluateJavaScript("var iOSApp = {\"getUserInfo\":function(){return \(jsonText!)}}", completionHandler: nil)
}
在WebView加载完成之后，使用evaluateJavaScript实现了JS函数的注入，H5实现调用正常。
H5传递信息给Native，调用Native分享
很多时候H5需要传递信息给我们的Native，我们Native再执行相应的逻辑。
Native实现代码如下
let userContent = WKUserContentController.init()
userContent.add(self, name: "shareAction")
let config = WKWebViewConfiguration.init()
config.userContentController = userContent
let wkWebView: WKWebView = WKWebView.init(frame: UIScreen.main.bounds, configuration: config)
wkWebView.navigationDelegate = self
wkWebView.uiDelegate = self
view.addSubview(wkWebView)
view.insertSubview(wkWebView, at: 0)
wkWebView.load(URLRequest.init(url: URL.init(string: "http://192.168.2.1/js.html")!))
...
//代理方法，window.webkit.messageHandlers.xxx.postMessage(xxx)实现发送到这里
func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
print(message.body)
print(message.name)
print(message.frameInfo.request)
if message.name == "shareAction" {
let list = message.body as! [String: String]
print(list["title"]!)
print(list["content"]!)
print(list["url"]!)
}
}
userContent.add(self, name: "shareAction")本地添加shareAction的接口声明，当JS调用shareAction回调代理方法，实现参数捕获(WKScriptMessage)。
这样我们本地就得到了分享的传参了，然后可以调用本地SDK实现分享的逻辑了。
H5实现代码如下
js Bridge demo
js demo test
Native告诉H5分享结果
上面实现了JS传参数给Native，但是Native怎么告诉H5分享结果呢，下面是实现逻辑。
Native实现如下
let userContent = WKUserContentController.init()
userContent.add(self, name: "shareAction")
let config = WKWebViewConfiguration.init()
config.userContentController = userContent
let wkWebView: WKWebView = WKWebView.init(frame: UIScreen.main.bounds, configuration: config)
wkWebView.navigationDelegate = self
wkWebView.uiDelegate = self
view.addSubview(wkWebView)
view.insertSubview(wkWebView, at: 0)
wkWebView.load(URLRequest.init(url: URL.init(string: "http://192.168.2.1/js.html")!))
...
//代理方法，window.webkit.messageHandlers.xxx.postMessage(xxx)实现发送到这里
func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
print(message.body)
print(message.name)
print(message.frameInfo.request)
if message.name == "shareAction" {
let list = message.body as! [Any]
let dict = list[0] as! [String: String]
print(dict["title"]!)
print(dict["content"]!)
print(dict["url"]!)
let shareSucc = list[1] as! String//获取回调JS，通知H5分享成功了
let script = "\(shareSucc)(true)"
wkWebView?.evaluateJavaScript(script, completionHandler: nil)
}
}
获取shareSucc的函数回调名称，在合适的时候我们可以通过这个JS函数回调，告诉H5我们的分享结果。
JS实现如下
js Bridge demo
js demo test
之前postMessage是发送的字典，由于我们的需求增多了，所以还是改成数组。
最后发送shareSucc的字符串，告诉Native我们有一个shareSucc的函数可以接收分享的结果。
JS和Native统一封装
上面讲了JS回调Native，Native回调JS，实现了我们常用的一些业务逻辑。
里面有很多重复的代码，实现起来也不友好，下面我们把这些重用的全部封装一下，改成好用的接口给上层，使Native和JS的开发人员都不用操心太多的实现细节。
H5界面的代码
js Bridge demo
js demo test
构造基础类JWebViewController
//
// JWebViewController.swift
// JSBridgeTest
//
// Created by jackyshan on 2018/9/26.
// Copyright © 2018年 GCI. All rights reserved.
//
import UIKit
import WebKit
class JWebViewController: UIViewController, WKUIDelegate, WKScriptMessageHandler {
private var mAsyncScriptArray:[JKWkWebViewHandler] = []
private var mSyncScriptArray:[JKWkWebViewHandler] = []
private var wkWebView: WKWebView?
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
public func startUrl(_ url: URL) {
let configuretion = WKWebViewConfiguration()
configuretion.preferences = WKPreferences()
configuretion.preferences.javaScriptEnabled = true
configuretion.userContentController = WKUserContentController()
if self.mAsyncScriptArray.count != 0 || self.mSyncScriptArray.count != 0 {
// 在载入时就添加JS // 只添加到mainFrame中
let script = WKUserScript(source: createScript(), injectionTime: .atDocumentStart, forMainFrameOnly: true)
configuretion.userContentController.addUserScript(script)
}
//异步需要回调，所以需要添加handler
for item in self.mAsyncScriptArray {
configuretion.userContentController.add(self, name: item.name)
}
let wkWebView = WKWebView(frame: self.view.bounds, configuration: configuretion)
wkWebView.uiDelegate = self
self.view.insertSubview(wkWebView, at: 0)
let request = URLRequest(url: url)
wkWebView.load(request)
self.wkWebView = wkWebView
}
override func viewDidDisappear(_ animated: Bool) {
super.viewDidDisappear(animated)
//释放handler
for item in self.mAsyncScriptArray {
wkWebView?.configuration.userContentController.removeScriptMessageHandler(forName: item.name)
wkWebView?.configuration.userContentController.removeAllUserScripts()
}
}
// MARK: - 添加JS
public func addAsyncJSFunc(functionName: String, parmers: [String], action: @escaping ([String:AnyObject]) -> Void) {
var obj = self.mAsyncScriptArray.filter { (obj) -> Bool in
return obj.name == functionName
}.first
if obj == nil {
obj = JKWkWebViewHandler()
obj!.name = functionName
obj!.parmers = parmers
obj!.action = action
self.mAsyncScriptArray.append(obj!)
}
}
public func addSyncJSFunc(functionName: String, parmers: [String]) {
var obj = self.mSyncScriptArray.filter { (obj) -> Bool in
return obj.name == functionName
}.first
if obj == nil {
obj = JKWkWebViewHandler()
obj!.name = functionName
obj!.parmers = parmers
self.mSyncScriptArray.append(obj!)
}
}
// MARK: - 插入JS
private func createScript() -> String {
var result = "iOSApp = {"
for item in self.mAsyncScriptArray {
let pars = createParmes(dict: item.parmers)
let str = "\"\(item.name!)\":function(\(pars)){window.webkit.messageHandlers.\(item.name!).postMessage([\(pars)]);},"
result += str
}
for item in self.mSyncScriptArray {
let pars = createParmes(dict: item.parmers)
let str = "\"\(item.name!)\":function(){return JSON.stringify(\(pars));},"
result += str
}
result = (result as NSString).substring(to: result.count - 1)
result += "}"
print("++++++++\(result)")
return result
}
private func createParmes(dict: [String]) -> String {
var result = ""
for key in dict {
result += key + ","
}
if result.count > 0 {
result = (result as NSString).substring(to: result.count - 1)
}
return result
}
// MARK: - 执行JS
public func actionJsFunc(functionName: String, pars: [AnyObject], completionHandler: ((Any?, Error?) -> Void)?) {
var parString = ""
for par in pars {
parString += "\(par),"
}
if parString.count > 0 {
parString = (parString as NSString).substring(to: parString.count - 1)
}
let function = "\(functionName)(\(parString));"
wkWebView?.evaluateJavaScript(function, completionHandler: completionHandler)
}
// MARK: - WKUIDelegate
public func webView(_ webView: WKWebView, runJavaScriptAlertPanelWithMessage message: String, initiatedByFrame frame: WKFrameInfo, completionHandler: @escaping () -> Void) {
let alert = UIAlertController(title: "提示", message: message, preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "确定", style: .default, handler: { (_) -> Void in
// We must call back js
completionHandler()
}))
self.present(alert, animated: true, completion: nil)
}
// MARK: - WKScriptMessageHandler
public func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
let funcObjs = self.mAsyncScriptArray.filter { (obj) -> Bool in
return obj.name == message.name
}
if let funcObj = funcObjs.first {
let pars = message.body as! [AnyObject]
var dict: [String: AnyObject] = [:]
for i in 0.. i {
dict[key] = pars[i]
}
}
funcObj.action?(dict)
}
}
}
class JKWkWebViewHandler: NSObject {
fileprivate var name:String!
fileprivate var parmers:[String]!
fileprivate var action:(([String:AnyObject]) -> Void)?
}
继承JWebViewController，实现业务
//
// ViewController.swift
// JSBridgeTest
//
// Created by jackyshan on 2018/9/26.
// Copyright © 2018年 GCI. All rights reserved.
//
import UIKit
class ViewController: JWebViewController {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
let userInfo = ["name": "wb", "sex": "male", "phone": "12333434"]
let jsonData = try? JSONSerialization.data(withJSONObject: userInfo, options: .prettyPrinted)
let jsonText = String.init(data: jsonData!, encoding: String.Encoding.utf8)
//添加getUserInfo脚本，返回用户信息
addSyncJSFunc(functionName: "getUserInfo", parmers: [jsonText!])
//添加shareAction脚本，获得分享参数
addAsyncJSFunc(functionName: "shareAction", parmers: ["name", "sex", "phone", "shareBack"]) { [weak self] (dict) in
print(dict["name"]!)
print(dict["sex"]!)
print(dict["phone"]!)
//执行shareBack脚本，告诉H5分享结果
self?.actionJsFunc(functionName: dict["shareBack"] as! String, pars: [true as AnyObject], completionHandler: nil)
}
//开始加载H5
startUrl(URL.init(string: "http://192.168.2.1/js.html")!)
}
}
讲解JWebViewController
构造JKWkWebViewHandler类，存储信息
class JKWkWebViewHandler: NSObject {
fileprivate var name:String!
fileprivate var parmers:[String]!
fileprivate var action:(([String:AnyObject]) -> Void)?
}
添加JS，使用JKWkWebViewHandler存储
public func addAsyncJSFunc(functionName: String, parmers: [String], action: @escaping ([String:AnyObject]) -> Void) {
var obj = self.mAsyncScriptArray.filter { (obj) -> Bool in
return obj.name == functionName
}.first
if obj == nil {
obj = JKWkWebViewHandler()
obj!.name = functionName
obj!.parmers = parmers
obj!.action = action
self.mAsyncScriptArray.append(obj!)
}
}
public func addSyncJSFunc(functionName: String, parmers: [String]) {
var obj = self.mSyncScriptArray.filter { (obj) -> Bool in
return obj.name == functionName
}.first
if obj == nil {
obj = JKWkWebViewHandler()
obj!.name = functionName
obj!.parmers = parmers
self.mSyncScriptArray.append(obj!)
}
}
创建JS脚本，使用iOSApp对象封装，异步回调传回Native的函数window.webkit.messageHandlers.xxx直接封装在JS函数中。
这样有一个好处，H5调用JS，直接iOSApp.xxx(xxx)就行了，不需要写window.webkit.messageHandlers.xxx这些代码。
这对于H5来说，跟平时写的JS脚本没有什么区别，方便了调用。
对于Native来说，帮H5做了JS的回调的封装，并通过handler回调得到自己想要的参数，通过这个封装，两端的工作都只需要关注
业务层就行了，继承JWebViewController，可以专心写业务逻辑。
private func createScript() -> String {
var result = "iOSApp = {"
for item in self.mAsyncScriptArray {
let pars = createParmes(dict: item.parmers)
let str = "\"\(item.name!)\":function(\(pars)){window.webkit.messageHandlers.\(item.name!).postMessage([\(pars)]);},"
result += str
}
for item in self.mSyncScriptArray {
let pars = createParmes(dict: item.parmers)
let str = "\"\(item.name!)\":function(){return JSON.stringify(\(pars));},"
result += str
}
result = (result as NSString).substring(to: result.count - 1)
result += "}"
print("++++++++\(result)")
return result
}
构造JS，实现传参给H5页面
public func actionJsFunc(functionName: String, pars: [AnyObject], completionHandler: ((Any?, Error?) -> Void)?) {
var parString = ""
for par in pars {
parString += "\(par),"
}
if parString.count > 0 {
parString = (parString as NSString).substring(to: parString.count - 1)
}
let function = "\(functionName)(\(parString));"
wkWebView?.evaluateJavaScript(function, completionHandler: completionHandler)
}
注入JS脚本到WKWebViewConfiguration中
let configuretion = WKWebViewConfiguration()
configuretion.preferences = WKPreferences()
configuretion.preferences.javaScriptEnabled = true
configuretion.userContentController = WKUserContentController()
if self.mAsyncScriptArray.count != 0 || self.mSyncScriptArray.count != 0 {
// 在载入时就添加JS // 只添加到mainFrame中
let script = WKUserScript(source: createScript(), injectionTime: .atDocumentStart, forMainFrameOnly: true)
configuretion.userContentController.addUserScript(script)
}
//异步需要回调，所以需要添加handler
for item in self.mAsyncScriptArray {
configuretion.userContentController.add(self, name: item.name)
}
let wkWebView = WKWebView(frame: self.view.bounds, configuration: configuretion)
合适的时候释放JS的handler，注意不释放的话，Controller不会调用deinit，发生内存泄露。
override func viewDidDisappear(_ animated: Bool) {
super.viewDidDisappear(animated)
//释放handler
for item in self.mAsyncScriptArray {
wkWebView?.configuration.userContentController.removeScriptMessageHandler(forName: item.name)
wkWebView?.configuration.userContentController.removeAllUserScripts()
}
}
代码示例放到Github了，有需要的可以下载查看。
关注我
欢迎关注公众号：jackyshan，技术干货首发微信，第一时间推送。
