Created
January 12, 2023 22:19
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Render SVG from data in swift
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| private func imageFrom(url: URL?, data: Data, response: HTTPURLResponse? = nil) -> AnyPublisher<UIImage?, Error> { | |
| let type = response?.mimeType | |
| if type?.hasPrefix("image/svg") == true || url?.pathExtension.lowercased() == "svg" { | |
| return svgFrom(data: data) | |
| } | |
| return Just(UIImage(data: data)).setFailureType(to: Error.self).eraseToAnyPublisher() | |
| } | |
| private func svgFrom(data: Data) -> AnyPublisher<UIImage?, Error> { | |
| let dataUri = "data:image/svg+xml;base64,\(data.base64EncodedString())" | |
| let html = """ | |
| <!doctype html> | |
| <meta name="viewport" content="width=device-width,initial-scale=1,user-scalable=no"> | |
| <style>*{margin:0;padding:0;height:100%;width:100%;}</style> | |
| <img src="\(dataUri)" style="object-position:center;object-fit:contain;" | |
| onload="setTimeout(()=>webkit.messageHandlers.svg.postMessage(''),17)" | |
| /> | |
| """ | |
| return Future { promise in | |
| DispatchQueue.main.async { | |
| let config = WKWebViewConfiguration() | |
| config.websiteDataStore = .nonPersistent() | |
| var webView: WKWebView? = WKWebView(frame: CGRect(x: 0, y: 0, width: 24, height: 24), configuration: config) | |
| webView?.backgroundColor = .clear | |
| webView?.isOpaque = false | |
| webView?.loadHTMLString(html, baseURL: nil) | |
| webView?.handle("svg") { _ in | |
| webView?.takeSnapshot(with: nil) { snapshot, error in | |
| webView = nil | |
| if let error = error { | |
| promise(.failure(error)) | |
| } else { | |
| promise(.success(snapshot)) | |
| } | |
| } | |
| } | |
| } | |
| } | |
| .eraseToAnyPublisher() | |
| } | |
| typealias MessageHandler = (WKScriptMessage) -> Void | |
| extension WKWebView { | |
| func handle(_ name: String, handler: @escaping MessageHandler) { | |
| let passer = MessagePasser(handler: handler) | |
| configuration.userContentController.removeScriptMessageHandler(forName: name) | |
| configuration.userContentController.add(passer, name: name) | |
| } | |
| } | |
| private class MessagePasser: NSObject, WKScriptMessageHandler { | |
| let handler: MessageHandler | |
| init(handler: @escaping MessageHandler) { | |
| self.handler = handler | |
| super.init() | |
| } | |
| func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) { | |
| handler(message) | |
| } | |
| } |
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