我有一个UITextView
,我使用ImagePickerController向其中添加图片。
如果只有文本,它会很流畅,但是在添加3或4张图片后,在其内容中滚动时会变得卡顿。
我在添加图像时对其进行了压缩,压缩到最低质量,但是仍然存在卡顿问题。
以下是代码:
func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
guard let _image = info[UIImagePickerControllerOriginalImage] as? UIImage else { return }
self.dismiss(animated: true, completion: nil)
// Compress the retrieved image
let compressedImage = UIImage(data: _image.lowestQualityJPEGNSData!)
//create and NSTextAttachment and add your image to it.
let attachment = NSTextAttachment()
let oldWidth = compressedImage?.size.width // scales it within the UITextView
let scaleFactor = oldWidth! / (bodyEditText.frame.size.width - 10); // adjusts the desired padding
attachment.image = UIImage(cgImage: (compressedImage?.cgImage!)!, scale: scaleFactor, orientation: .up)
//put your NSTextAttachment into and attributedString
let attString = NSAttributedString(attachment: attachment)
//add this attributed string to the current position.
bodyEditText.textStorage.insert(attString, at: bodyEditText.selectedRange.location)
}
extension UIImage {
var uncompressedPNGData: Data? { return UIImagePNGRepresentation(self) }
var highestQualityJPEGNSData: Data? { return UIImageJPEGRepresentation(self, 1.0) }
var highQualityJPEGNSData: Data? { return UIImageJPEGRepresentation(self, 0.75) }
var mediumQualityJPEGNSData: Data? { return UIImageJPEGRepresentation(self, 0.5) }
var lowQualityJPEGNSData: Data? { return UIImageJPEGRepresentation(self, 0.25) }
var lowestQualityJPEGNSData:Data? { return UIImageJPEGRepresentation(self, 0.0) }
}
这个问题的原因是什么?你有什么技巧可以解决这个问题吗?
谢谢帮忙。
编辑:
感谢 Duncan C,我成功地消除了整个延迟,并大大提高了渲染图像的性能。
通过替换我的 imagePickerController 为以下内容来实现:
let size = __CGSizeApplyAffineTransform(_image.size, CGAffineTransform.init(scaleX: 0.3, y: 0.3))
let hasAlpha = false
let scale: CGFloat = 0.0 // Automatically use scale factor of main screen
UIGraphicsBeginImageContextWithOptions(size, !hasAlpha, scale)
_image.draw(in: CGRect(origin: CGPoint.zero, size: size))
let scaledImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
let att = NSTextAttachment()
att.image = scaledImage
//put your NSTextAttachment into and attributedString
let attString = NSAttributedString(attachment: att)
//add this attributed string to the current position.
bodyEditText.textStorage.insert(attString, at: bodyEditText.selectedRange.location)
attachment.image = ...
在缩放图像后将其分配给 attachment.image。 - Duncan C