WKWebView JS注入

碰到个webview页面突然被放大了，查看html源码发现：

<meta name="viewport" content="initial-scale=0.3333333333333333, maximum-scale=0.3333333333333333, minimum-scale=0.3333333333333333, user-scalable=no">

所以想到了对html进行js注入

WKUserScriptInjectionTimeAtDocumentStart : 注入时机为document的元素生成以后,其余内容load以前.

WKUserScriptInjectionTimeAtDocumentEnd : 注入时机为document所有load完成,任意子资源load完成以前.

- (WKWebView *)webView
{
    if (!_webView) {
        NSString *jScript = @"var script = document.createElement('meta');script.name = 'viewport';script.content='width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0,user-scalable=no';document.getElementsByTagName('head')[0].appendChild(script);";
        //注意修改meta的js注入一定要选WKUserScriptInjectionTimeAtDocumentStart，否则不生效
        WKUserScript *wkUScript = [[WKUserScript alloc] initWithSource:jScript injectionTime:WKUserScriptInjectionTimeAtDocumentStart forMainFrameOnly:YES];
        WKUserContentController * wkUController = [[WKUserContentController alloc] init];
        [wkUController addUserScript:wkUScript];
        WKWebViewConfiguration *wkWebConfig = [[WKWebViewConfiguration alloc] init];
        wkWebConfig.userContentController= wkUController;

        _webView = [[WKWebView alloc] initWithFrame:CGRectMake(0, 0 , 375, 812)  configuration:wkWebConfig];
        _webView.backgroundColor = [UIColor whiteColor];
        _webView.navigationDelegate = self;
        _webView.UIDelegate = self;
    }
    
    return _webView;
}