在UITextView中拖放时显示文本光标

我正在我的应用程序中实现拖放。

将应用拖放(主要是拖放)的主屏幕之一位于 UITextView .

我添加了一个下拉交互 UITextView 代码如下:

    let dropInteraction = UIDropInteraction(delegate: self)     
    inputTextView.addInteraction(dropInteraction)

通过这样做,我现在接受它的下降。

为了只接受图像和文本作为drop,我实现了以下委托方法:

func dropInteraction(_ interaction: UIDropInteraction, canHandle session: UIDropSession) -> Bool {
    return session.hasItemsConforming(toTypeIdentifiers: [kUTTypeImage as String, kUTTypeText as String]) && session.items.count == 1
}

根据需要,我还实现了以下所需的委托方法来返回 UIDropProposal :

func dropInteraction(_ interaction: UIDropInteraction, sessionDidUpdate session: UIDropSession) -> UIDropProposal {
    let dropProposal: UIDropProposal = UIDropProposal(operation: .copy)
    dropProposal.isPrecise = true
    return dropProposal
}

然后在performDrop委托方法中,我处理丢弃的内容并将其附加到 UITextView

func dropInteraction(_ interaction: UIDropInteraction, performDrop session: UIDropSession) {
    // Access the dropped object types: UIImage, NSString
    session.loadObjects(ofClass: UIImage.self) { (imageItems) in

        let images = imageItems as! [UIImage]
        guard var image = images.first else { return }
        // scale the image 
        image = UIImage(cgImage: image.cgImage!, scale: 4, orientation: .up)

        let currentText: NSMutableAttributedString = NSMutableAttributedString(attributedString: self.inputTextView.attributedText)
        let textAttachment = NSTextAttachment()
        textAttachment.image = image
        let imageText = NSAttributedString(attachment: textAttachment).mutableCopy() as! NSMutableAttributedString
        let imageStyle = NSMutableParagraphStyle()
        imageStyle.alignment = .center

        imageText.addAttribute(NSAttributedStringKey.paragraphStyle, value: imageStyle, range: NSMakeRange(0, imageText.length))

        // Prepares the string to append with line breaks and the image centered
        let attributedStringToAppend: NSMutableAttributedString = NSMutableAttributedString(attributedString: NSAttributedString(string: "\n\n"))
        attributedStringToAppend.append(imageText)
        attributedStringToAppend.append(NSAttributedString(string: "\n\n"))

        // Applies text attributes to the NSMutableAttrString as the default text input attributes
        let range: NSRange = NSRange.init(location: 0, length: attributedStringToAppend.length)
        let style = NSMutableParagraphStyle()
        style.lineSpacing = 4
        style.alignment = .center
        let font = Font(.installed(.OpenSansRegular), size: .custom(18)).instance
        let attr: [NSAttributedStringKey : Any] = [NSAttributedStringKey(rawValue: NSAttributedStringKey.paragraphStyle.rawValue): style, NSAttributedStringKey(rawValue: NSAttributedStringKey.font.rawValue): font, NSAttributedStringKey(rawValue: NSAttributedStringKey.foregroundColor.rawValue): UIColor.rgb(red: 52, green: 52, blue: 52)]

        attributedStringToAppend.addAttributes(attr, range: range)

        let location = self.inputTextView.selectedRange.location

        currentText.insert(attributedStringToAppend, at: location)

        self.inputTextView.attributedText = currentText                     
    }

    session.loadObjects(ofClass: NSString.self) { (stringItems) in
        let strings = stringItems as! [NSString]
        guard let text = strings.first else { return }
        self.inputTextView.insertText(text as String)
    }                   
}

通过所有这些操作,图像和文本都会像预期的那样被放到所需的字段中,但我这里有一个问题。

在 New Mail Composer 在mail应用程序中,当您将项目或图像拖动到其中时,它会显示一个跟踪光标,以便您知道放置内容的位置,但在我的示例中我无法做到这一点。

如果我想下降到一个特定的位置,我必须先把光标放在所需的位置,然后执行下降,所以在 performDrop 如您所见,我通过 selectedRange .

我想在拖放动画发生时看到光标流,就像mail应用程序或notes应用程序一样,在那里你可以选择拖放对象的位置。

有人对如何实现这一点有什么建议吗?