ios - 将屏幕截图转换为 UIImage UIImagePNGRepresentation

Question

下面我将屏幕截图转换为NSData UIImagePNGRepresentation.

但是如何更正下面的代码并将屏幕截图转换为UIImagePNGRepresentation但确保它使用的是UIImage格式而不是NSData？

// Take snapshot of screen
var imageSnapshot: UIImage!
UIGraphicsBeginImageContextWithOptions(self.view.frame.size, false, 0)
self.view.drawViewHierarchyInRect(CGRect(x: 0, y: 0, width: self.view.bounds.width, height: self.view.bounds.height), afterScreenUpdates: false)
imageSnapshot = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()

// Prepare image to PNG format
let imageShare: NSData
imageShare = UIImagePNGRepresentation(imageSnapshot)!