iOS 进阶之 WKWebView

前言

Xcode8发布之后,编译器开始不支持 iOS7了.很多应用在适配 iOS10之后都不再适配 iOS7了.最低适配到 iOS8,所以第一个要更改的是用 WKWebView替换原来的UIWebView.并且 WKWebView 有很多明显的优势.

• 更多的支持 HTML5的特性
• 官方宣称的高达60fps 的滚动刷新率以及内置手势
• 将 UIWebViewDelegate 与 UIWebView 拆分了14个类和3个协议,以前很多不方便实现的功能得以实现.文档
• 和Safair 相同的 JavaScript 引擎
• 占用更少的内存

一 基本使用方法

---

WKWebView有两个delegate,WKUIDelegate 和 WKNavigationDelegate。WKNavigationDelegate主要处理一些跳转、加载处理操作，WKUIDelegate主要处理JS脚本，确认框，警告框等。因此WKNavigationDelegate更加常用。

• 初始化 WKWebView

- (void)drawUI {    
    WKWebView *webView = [[WKWebView alloc] initWithFrame:self.view.bounds];
    _webView = webView;
    webView.UIDelegate = self;
    webView.navigationDelegate = self;
    [self.view addSubview:webView];
    
    [webView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.baidu.com"]]];
}

• WKNavigationDelegate代理方法

// 页面开始加载时调用
- (void)webView:(WKWebView *)webView didStartProvisionalNavigation:(WKNavigation *)navigation {
    NSLog(@"didStartProvisionalNavigation");
}

// 当内容开始返回时调用
- (void)webView:(WKWebView *)webView didCommitNavigation:(WKNavigation *)navigation {
    NSLog(@"didCommitNavigation");
}

// 页面加载完成时调用
- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation {
    NSLog(@"didFinishNavigation");
    
    //say()是JS方法名，completionHandler是异步回调block
    [webView evaluateJavaScript:@"say()" completionHandler:^(id _Nullable result, NSError * _Nullable error) {
        NSLog(@"evaluateJavaScript %@",result);
    }];
}

// 页面加载失败时调用
- (void)webView:(WKWebView *)webView didFailProvisionalNavigation:(WKNavigation *)navigation withError:(NSError *)error {
    NSLog(@"didFailProvisionalNavigation");
}

// 接收到服务器跳转请求之后调用
- (void)webView:(WKWebView *)webView didReceiveServerRedirectForProvisionalNavigation:(WKNavigation *)navigation {
    NSLog(@"didReceiveServerRedirectForProvisionalNavigation");
}

// 在收到响应后,决定是否跳转
- (void)webView:(WKWebView *)webView decidePolicyForNavigationResponse:(WKNavigationResponse *)navigationResponse decisionHandler:(void (^)(WKNavigationResponsePolicy))decisionHandler {
    NSLog(@"decidePolicyForNavigationResponse:%@",navigationResponse.response.URL.absoluteString);
    //允许跳转
    decisionHandler(WKNavigationResponsePolicyAllow);
    //不允许跳转
    //decisionHandler(WKNavigationResponsePolicyCancel);
}

// 在发送请求之前,决定是否跳转
- (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler {
    NSLog(@"decidePolicyForNavigationAction:%@",navigationAction.request.URL.absoluteString);
    //允许跳转
    decisionHandler(WKNavigationActionPolicyAllow);
    //不允许跳转
    //decisionHandler(WKNavigationActionPolicyCancel);
}

• WKUIDelegate代理方法

// 创建一个新的 webView
- (WKWebView *)webView:(WKWebView *)webView createWebViewWithConfiguration:(WKWebViewConfiguration *)configuration forNavigationAction:(WKNavigationAction *)navigationAction windowFeatures:(WKWindowFeatures *)windowFeatures {
    return [[WKWebView alloc] init];
}

// 输入框
- (void)webView:(WKWebView *)webView runJavaScriptTextInputPanelWithPrompt:(NSString *)prompt defaultText:(NSString *)defaultText initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(NSString * _Nullable))completionHandler {
    completionHandler(@"http");
}

// 确认框
- (void)webView:(WKWebView *)webView runJavaScriptConfirmPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(BOOL))completionHandler {
    completionHandler(YES);
}

// 警告框
- (void)webView:(WKWebView *)webView runJavaScriptAlertPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(void))completionHandler {
    completionHandler();
}

二 OC 与 JS 交互

---

WKWebview提供了API实现js交互 不需要借助JavaScriptCore或者webJavaScriptBridge。使用WKUserContentController实现js native交互。简单的说就是先注册约定好的方法，然后再调用。

JS 调用 OC 方法

• WKDelegateViewController.h文件代码

#import <UIKit/UIKit.h>
#import <WebKit/WebKit.h>

@protocol WKDelegate <NSObject>

- (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message;

@end

@interface WKDelegateViewController : UIViewController <WKScriptMessageHandler>

/** 代理 */
@property(nonatomic, weak) id<WKDelegate> delegate;

@end

• WKDelegateViewController.m 文件代码

#import "WKDelegateViewController.h"

@interface WKDelegateViewController ()

@end

@implementation WKDelegateViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
}

- (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message {
    if ([self.delegate respondsToSelector:@selector(userContentController:didReceiveScriptMessage:)]) {
        [self.delegate userContentController:userContentController didReceiveScriptMessage:message];
    }
}

@end

• 主文件代码

#import "WKWebViewController.h"
#import <WebKit/WebKit.h>
#import "WKDelegateViewController.h"

@interface WKWebViewController ()<WKUIDelegate, WKNavigationDelegate,WKScriptMessageHandler,WKDelegate>

@end

@implementation WKWebViewController {
    WKWebView *_webView;
    WKUserContentController *_userContentController;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    [self setupData];
    [self drawUI];
}

- (void)dealloc {
    NSLog(@"WKWebViewController dealloc");
    //这里需要注意，前面增加过的方法一定要remove掉。
    [_userContentController removeScriptMessageHandlerForName:@"sayhello"];
}

- (void)setupData {
    self.view.backgroundColor = [UIColor whiteColor];
    self.title = @"WKWebView";
}

- (void)drawUI {
    // 配置环境
    WKWebViewConfiguration *configuration = [[WKWebViewConfiguration alloc] init];
    _userContentController = [[WKUserContentController alloc] init];
    configuration.userContentController = _userContentController;
    // 注册方法
    WKDelegateViewController *delegateVC = [[WKDelegateViewController alloc] init];
    delegateVC.delegate = self;
    
    [_userContentController addScriptMessageHandler:delegateVC name:@"sayhello"];
    
    WKWebView *webView = [[WKWebView alloc] initWithFrame:self.view.bounds];
    _webView = webView;
    webView.UIDelegate = self;
    webView.navigationDelegate = self;
    [self.view addSubview:webView];
    
    NSString *path = [[NSBundle mainBundle] pathForResource:@"Company-2" ofType:@"html"];
    [webView loadRequest:[NSURLRequest requestWithURL:[NSURL fileURLWithPath:path]]];
}

#pragma mark - WKScriptMessageHandler

- (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message {
    NSLog(@"name:%@\\\\n body:%@\\\\n frameInfo:%@\\\\n",message.name,message.body,message.frameInfo);
}

• h5代码

<!DOCTYPE html>
<html>
    <head>
        <script>
            function say()
            {
                //前端需要用 window.webkit.messageHandlers.注册的方法名.postMessage({body:传输的数据} 来给native发送消息
                window.webkit.messageHandlers.sayhello.postMessage({body: 'hello world!'});
            }
        </script>
    </head>
    <body>
        <h1>hello world</h1>
        <button onclick="say()">say hello</button>
    </body>
    
</html>

打印出的 log 日志:

注意点

• addScriptMessageHandler要和removeScriptMessageHandlerForName配套出现，否则会造成内存泄漏。
• h5只能传一个参数，如果需要多个参数就需要用字典或者json组装。

---

OC 调用 JS 方法

代码如下

// 页面加载完成时调用
- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation {
    NSLog(@"didFinishNavigation");
    
    //say()是JS方法名，completionHandler是异步回调block
    [webView evaluateJavaScript:@"say()" completionHandler:^(id _Nullable result, NSError * _Nullable error) {
        NSLog(@"evaluateJavaScript %@",result);
    }];
}

h5代码同上

本文参考IOS进阶之WKWebView,非常感谢该作者
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