WKWebview 解决因userContentController调用addScriptMessageHandler导致循环引用的问题

关键类

LeakAvoider.h

#import <Foundation/Foundation.h>
#import <WebKit/WebKit.h>
NS_ASSUME_NONNULL_BEGIN

@interface LeakAvoider : NSObject<WKScriptMessageHandler>

- (instancetype)initWithMessageHandler:(id <WKScriptMessageHandler>)messageHander;
@end

NS_ASSUME_NONNULL_END

LeakAvoider.m

#import "LeakAvoider.h"


@interface LeakAvoider ()
@property (nonatomic, weak) id <WKScriptMessageHandler> scriptDelegate;
@end

@implementation LeakAvoider
- (instancetype)initWithMessageHandler:(id <WKScriptMessageHandler>)messageHander {
    if (self = [super init]) {
        _scriptDelegate = messageHander;
    }
    return self;
}

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

使用方式

#import <UIKit/UIKit.h>

NS_ASSUME_NONNULL_BEGIN

@interface WebVC : UIViewController

@end

NS_ASSUME_NONNULL_END



@interface WebVC ()<WKUIDelegate, WKNavigationDelegate, WKScriptMessageHandler>

@property (nonatomic, strong) WKWebView *webView;

@end
@implementation WebVC

- (void)viewDidLoad {
    [super viewDidLoad];
    
    self.view.backgroundColor = [UIColor whiteColor];
    
    WKWebViewConfiguration *config = [[WKWebViewConfiguration alloc] init];
    WKWebView *webView = [[WKWebView alloc] initWithFrame:self.view.bounds configuration:config];
    webView.customUserAgent = @"Mozilla/5.0 (iPad; CPU OS 12_4_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/12.1.2 Mobile/15E148 Safari/604.1";
    webView.UIDelegate = self;
    webView.navigationDelegate = self;
//    [webView.configuration.userContentController addScriptMessageHandler:self name:@"Share"];
    [webView.configuration.userContentController addScriptMessageHandler:[[LeakAvoider alloc] initWithMessageHandler:self] name:@"Share"];
    [self.view addSubview:webView];
    
    _webView = webView;
}

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
    NSString *path = [[NSBundle mainBundle] pathForResource:@"index" ofType:@"html"];
    NSString *content = [NSString stringWithContentsOfFile:path encoding:NSUTF8StringEncoding error:nil];
    [self.webView loadHTMLString:content baseURL:nil];
//    NSMutableURLRequest *req = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:@"https://www.baidu.com"]];
//    req.cachePolicy = NSURLRequestReloadIgnoringLocalAndRemoteCacheData;
//    [self.webView loadRequest:req];
}


- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation {
    
}
- (void)webView:(WKWebView *)webView didFailNavigation:(WKNavigation *)navigation withError:(NSError *)error {
    
}
- (void)webView:(WKWebView *)webView didFailProvisionalNavigation:(WKNavigation *)navigation withError:(NSError *)error {
    
}

- (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message {
    NSLog(@"%@", message);
}

- (void)dealloc {
    NSLog(@"%@ 销毁了", self);
    [self.webView.configuration.userContentController removeScriptMessageHandlerForName:@"Share"];
}

@end

总结

1、addScriptMessageHandler时不要用self了

2、控制器中的dealloc方法中记得调用removeScriptMessageHandlerForName

附：用到的本地html

<!DOCTYPE html>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf8">
        <script language="javascript">

        //JS执行window.webkit.messageHandlers.Share.postMessage(<messageBody>)
        function shareClick() {
            window.webkit.messageHandlers.Share.postMessage({title:'测试分享的标题',content:'测试分享的内容',url:'https://github.com/maying1992'});
        }
        
        //分享回调结果显示
        function shareResult(channel_id,share_channel,share_url) {
            var content = channel_id+","+share_channel+","+share_url;
            alert(content);
            document.getElementById("returnValue").value = content;
        }
        
        //JS执行window.webkit.messageHandlers.Camera.postMessage(<messageBody>)
        function cameraClick() {
            window.webkit.messageHandlers.Camera.postMessage(null);
        }
        
        //调用相册回调结果显示
        function cameraResult(result) {
            alert(result);
            document.getElementById("returnValue")/Users/zjt/Desktop/ceshiyinpin/ceshiyinpin/index.html.value = result;
        }
            </script>
        </head>

<body>
    <h1>这是按钮调用</h1>
    <input type="button" value="分享" onclick="shareClick()" />
    <input type="button" value="相机" onclick="cameraClick()" />

    <h1>回调展示区</h1>
    <textarea id ="returnValue" type="value" rows="5" cols="40">
        
    </textarea>
    
    <br/>
    <font style="color:#666666"> 外部
    <a style="text-decoration:none;color:red" href="https://www.baidu.com">百度一下</a>
    </font>
</body>
</html>

WKWebview 解决因userContentController调用addScriptMessageHandler导致循环引用的问题

总结

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