如何将javascript文件注入来自api的html字符串？

您可以使用WKUserScript并使用WKWebViewConfiguration将javascript附加到webview。

let contentController = WKUserContentController()
guard let scriptPath = Bundle.main.path(forResource: "script", ofType: "js"),
let scriptSource = try? String(contentsOfFile: scriptPath) else { return }
let script = WKUserScript(source: scriptSource, injectionTime: .atDocumentEnd, forMainFrameOnly: true)
contentController.addUserScript(script)
let config = WKWebViewConfiguration()
config.userContentController = contentController

let webView = WKWebView(frame: .zero, configuration: config)
self.view.addSubview(webView)

webView.loadHTMLString(htmlString, baseURL: nil)