UIMarkupTextPrintFormatter
似乎不支持HTMLimg
标记.苹果的文档在这里并没有提供太多信息,它只是说明初始化参数是"The HTML markup text for the print formatter".对于打印格式化程序支持哪些标签,目前还没有明确的说明.
很多图片显示了我只能支持UIMarkupTextPrintFormatter
次测试后得出的结论.
那么,对于那些希望从HTML内容中创建PDF的人来说,这会给他们带来什么便利呢?
因此,我发现实现这一点的唯一方法是使用一个隐藏的web视图,加载html内容,然后使用web视图的UIViewPrintFormatter
.这是可行的,但感觉真的像黑客.
它确实可以工作,它会将图像嵌入到你的PDF文档中,但是如果是我,我会倾向于使用CoreText和Quartz 2D,因为你会对PDF生成过程有更多的控制,虽然我说我理解这可能有些过分,但我不知道你的html内容的大小或复杂性.
下面是一个有效的例子...
Setup
定义一个基本url非常有用,这样我就可以只传入我想要使用的图像的文件名.映射到应用程序包中图像所在目录的基本url.你也可以定义自己的位置.
Bundle.main.resourceURL + "www/"
然后我创建了一个协议来处理与文档相关的功能.默认实现由一个扩展提供,如下面的代码所示.
protocol DocumentOperations {
// Takes your image tags and the base url and generates a html string
func generateHTMLString(imageTags: [String], baseURL: String) -> String
// Uses UIViewPrintFormatter to generate pdf and returns pdf location
func createPDF(html: String, formmatter: UIViewPrintFormatter, filename: String) -> String
// Wraps your image filename in a HTML img tag
func imageTags(filenames: [String]) -> [String]
}
extension DocumentOperations {
func imageTags(filenames: [String]) -> [String] {
let tags = filenames.map { "<img src=\"\($0)\">" }
return tags
}
func generateHTMLString(imageTags: [String], baseURL: String) -> String {
// Example: just using the first element in the array
var string = "<!DOCTYPE html><head><base href=\"\(baseURL)\"></head>\n<html>\n<body>\n"
string = string + "\t<h2>PDF Document With Image</h2>\n"
string = string + "\t\(imageTags[0])\n"
string = string + "</body>\n</html>\n"
return string
}
func createPDF(html: String, formmatter: UIViewPrintFormatter, filename: String) -> String {
// From: https://gist.github.com/nyg/b8cd742250826cb1471f
print("createPDF: \(html)")
// 2. Assign print formatter to UIPrintPageRenderer
let render = UIPrintPageRenderer()
render.addPrintFormatter(formmatter, startingAtPageAt: 0)
// 3. Assign paperRect and printableRect
let page = CGRect(x: 0, y: 0, width: 595.2, height: 841.8) // A4, 72 dpi
let printable = page.insetBy(dx: 0, dy: 0)
render.setValue(NSValue(cgRect: page), forKey: "paperRect")
render.setValue(NSValue(cgRect: printable), forKey: "printableRect")
// 4. Create PDF context and draw
let pdfData = NSMutableData()
UIGraphicsBeginPDFContextToData(pdfData, CGRect.zero, nil)
for i in 1...render.numberOfPages {
UIGraphicsBeginPDFPage();
let bounds = UIGraphicsGetPDFContextBounds()
render.drawPage(at: i - 1, in: bounds)
}
UIGraphicsEndPDFContext();
// 5. Save PDF file
let path = "\(NSTemporaryDirectory())\(filename).pdf"
pdfData.write(toFile: path, atomically: true)
print("open \(path)")
return path
}
}
然后我让视图控制器采用了这个协议.实现这一点的关键在于,您的视图控制器需要采用UIWebViewDelegate
和
class ViewController: UIViewController, DocumentOperations {
@IBOutlet private var webView: UIWebView!
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
webView.delegate = self
webView.alpha = 0
if let html = prepareHTML() {
print("html document:\(html)")
webView.loadHTMLString(html, baseURL: nil)
}
}
fileprivate func prepareHTML() -> String? {
// Create Your Image tags here
let tags = imageTags(filenames: ["PJH_144.png"])
var html: String?
// html
if let url = Bundle.main.resourceURL {
// Images are stored in the app bundle under the 'www' directory
html = generateHTMLString(imageTags: tags, baseURL: url.absoluteString + "www/")
}
return html
}
}
extension ViewController: UIWebViewDelegate {
func webViewDidFinishLoad(_ webView: UIWebView) {
if let content = prepareHTML() {
let path = createPDF(html: content, formmatter: webView.viewPrintFormatter(), filename: "MyPDFDocument")
print("PDF location: \(path)")
}
}
}