WKWebView加载的网页自适应大小

有时候在WKWebView加载页面后会发现页面的字会很小, 这是因为原网页没有做手机屏幕尺寸的适配, 那么在后台不做调整的情况下我们移动端怎样来适配页面呢?
以下代码可以适配大小

//Lazy Loading
- (WKWebView *)webView {
    if (!_webView) {
        _webView = [[WKWebView alloc] init];
        //以下代码适配大小
        NSString *jScript = @"var meta = document.createElement('meta'); meta.setAttribute('name', 'viewport'); meta.setAttribute('content', 'width=device-width'); document.getElementsByTagName('head')[0].appendChild(meta);";
        
        WKUserScript *wkUScript = [[WKUserScript alloc] initWithSource:jScript injectionTime:WKUserScriptInjectionTimeAtDocumentEnd forMainFrameOnly:YES];
        WKUserContentController *wkUController = [[WKUserContentController alloc] init];
        [wkUController addUserScript:wkUScript];
        
        WKWebViewConfiguration *wkWebConfig = [[WKWebViewConfiguration alloc] init];
        wkWebConfig.userContentController = wkUController;
        
        _webView = [[WKWebView alloc] initWithFrame:self.view.frame configuration:wkWebConfig];
        [self.view addSubview:_webView];
        _webView.navigationDelegate = self;
    }
    return _webView;
}