AirPrint UIView 的内容

我正在尝试通过 iPad 应用程序设置打印，其中单击“打印”将打印包含其所有内容的视图。这是我尝试过的（从网上的一些示例中提取的）：

// This is the View I want to print
// Just a 200x200 blue square
var testView = UIView(frame: CGRectMake(0, 0, 200, 200))
testView.backgroundColor = UIColor.blueColor()

let printInfo = UIPrintInfo(dictionary:nil)!
printInfo.outputType = UIPrintInfoOutputType.General
printInfo.jobName = "My Print Job"

// Set up print controller
let printController = UIPrintInteractionController.sharedPrintController()
printController!.printInfo = printInfo
// This is where I was thinking the print job got the
// contents to print to the page??
printController?.printFormatter = testView.viewPrintFormatter()

// Do it
printController!.presentFromRect(self.frame, inView: self, animated: true, completionHandler: nil)

不过，我也读过here https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIViewPrintFormatter_Class/index.html#//apple_ref/occ/cl/UIViewPrintFormatter that viewPrintFormatter仅适用于 UIWebView、UITextView 和 MKMapView，对吗？

当我用它打印时（使用打印机模拟器），我只是得到一个空白页；尝试过各种打印机/纸张尺寸。

非常感谢任何指导！

我不确定这是否是正确的方法，但我最终通过将视图转换为UIImage然后将其设置为打印控制器的printingItem.

更新的代码：

// This is the View I want to print
// Just a 200x200 blue square
var testView = UIView(frame: CGRectMake(0, 0, 200, 200))
testView.backgroundColor = UIColor.blueColor()

let printInfo = UIPrintInfo(dictionary:nil)!
printInfo.outputType = UIPrintInfoOutputType.General
printInfo.jobName = "My Print Job"

// Set up print controller
let printController = UIPrintInteractionController.sharedPrintController()
printController!.printInfo = printInfo

// Assign a UIImage version of my UIView as a printing iten
printController?.printingItem = testView!.toImage()

// Do it
printController!.presentFromRect(self.frame, inView: self, animated: true, completionHandler: nil)

The toImage()方法是 UIView 的扩展：

extension UIView {
    func toImage() -> UIImage {
        UIGraphicsBeginImageContextWithOptions(bounds.size, false, UIScreen.mainScreen().scale)

        drawViewHierarchyInRect(self.bounds, afterScreenUpdates: true)

        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return image
    }
}

如果有人有其他方法，请接受其他方法！