如何为UITextView中的NSTextAttachment配置圆形UIPointerInteraction？

要让自定义UITextView里的NSTextAttachment在触控板悬停时显示圆形指针，核心是通过UIPointerInteraction配置指针样式，以下是两种可行方案：

方案一：给UITextView全局添加指针交互（适配所有附件） #

通过监听UITextView的悬停位置，判断是否落在附件范围内，动态切换指针样式：

import UIKit

class CustomTextView: UITextView, UIPointerInteractionDelegate {
    
    override init(frame: CGRect, textContainer: NSTextContainer?) {
        super.init(frame: frame, textContainer: textContainer)
        setupPointerInteraction()
    }
    
    required init?(coder: NSCoder) {
        super.init(coder: coder)
        setupPointerInteraction()
    }
    
    private func setupPointerInteraction() {
        let pointerInteraction = UIPointerInteraction(delegate: self)
        addInteraction(pointerInteraction)
    }
    
    // 判断悬停点是否对应某个文本附件
    private func getAttachmentAtHoverPoint(_ point: CGPoint) -> NSTextAttachment? {
        let convertedPoint = convert(point, from: window)
        let charIndex = layoutManager.characterIndex(for: convertedPoint, 
                                                     in: textContainer, 
                                                     fractionOfDistanceBetweenInsertionPoints: nil)
        
        guard charIndex < textStorage.length else { return nil }
        let attributes = textStorage.attributes(at: charIndex, effectiveRange: nil)
        return attributes[.attachment] as? NSTextAttachment
    }
    
    // MARK: UIPointerInteractionDelegate
    func pointerInteraction(_ interaction: UIPointerInteraction, styleFor region: UIPointerRegion) -> UIPointerStyle? {
        guard let hoverPoint = region.location, getAttachmentAtHoverPoint(hoverPoint) != nil else {
            return nil // 非附件区域用默认指针
        }
        
        // 创建圆形指针，半径可根据需求调整（Apple Notes约为12）
        let circleShape = UIPointerShape.circular(radius: 12)
        return UIPointerStyle(effect: .highlight, shape: circleShape)
    }
}

方案二：给单个附件的ContentView添加指针交互（精准控制） #

如果你的NSTextAttachment使用了自定义contentView，可以直接给该视图绑定指针交互：

// 创建带自定义视图的文本附件
let attachment = NSTextAttachment()
let contentView = UIView(frame: CGRect(x: 0, y: 0, width: 40, height: 40))
contentView.backgroundColor = .lightGray
attachment.contentView = contentView

// 给ContentView添加指针交互
let pointerInteraction = UIPointerInteraction(delegate: self)
contentView.addInteraction(pointerInteraction)

// 实现代理方法返回圆形样式
extension YourViewController: UIPointerInteractionDelegate {
    func pointerInteraction(_ interaction: UIPointerInteraction, styleFor region: UIPointerRegion) -> UIPointerStyle? {
        let circleShape = UIPointerShape.circular(radius: 12)
        return UIPointerStyle(effect: .highlight, shape: circleShape)
    }
}

注意事项 #

• 确保UITextView的userInteractionEnabled属性为true（默认开启）
• 方案一中的坐标转换要准确，避免误判悬停区域
• 圆形指针的半径可根据附件大小自行调整，匹配视觉需求

内容的提问来源于stack exchange，提问作者a.wip