如何获取文件的com.apple.icns数据用于填充粘贴板？

• 直接读取现成的.icns文件
  要是你处理的是应用程序（.app包）这类本身带.icns文件的资源，直接去包的Contents/Resources目录里读取对应的.icns文件数据就行：

  if let appURL = Bundle.main.url(forResource: "AppIcon", withExtension: "icns") {
      do {
          let icnsData = try Data(contentsOf: appURL)
          // 写入粘贴板
          let pasteboard = NSPasteboard.general
          pasteboard.clearContents()
          pasteboard.setData(icnsData, forType: NSPasteboard.PasteboardType(rawValue: "com.apple.icns"))
      } catch {
          print("读取icns文件失败: \(error)")
      }
  }
  

• 从NSImage转成.icns格式
  普通文件的图标可以通过NSWorkspace拿到NSImage，再把它转成完整的.icns数据——NSImage本身包含多分辨率图，转成.icns后会保留这些信息：

  func icnsData(from image: NSImage) -> Data? {
      guard !image.representations.isEmpty else { return nil }
      
      let bitmapRep = NSBitmapImageRep(bitmapDataPlanes: nil, 
                                       pixelsWide: Int(image.size.width), 
                                       pixelsHigh: Int(image.size.height),
                                       bitsPerSample: 8, 
                                       samplesPerPixel: 4, 
                                       hasAlpha: true, 
                                       isPlanar: false, 
                                       colorSpaceName: .calibratedRGB, 
                                       bytesPerRow: 0, 
                                       bitsPerPixel: 0)
      
      bitmapRep?.size = image.size
      let context = NSGraphicsContext(bitmapImageRep: bitmapRep!)
      NSGraphicsContext.saveGraphicsState()
      NSGraphicsContext.current = context
      image.draw(at: .zero, from: .zero, operation: .copy, fraction: 1.0)
      NSGraphicsContext.restoreGraphicsState()
      
      return bitmapRep?.representation(using: .icns, properties: [:])
  }
  
  // 使用示例：拿文件图标转成icns再写入粘贴板
  let fileURL = URL(fileURLWithPath: "/path/to/your/file")
  if let icon = NSWorkspace.shared.icon(forFile: fileURL.path) {
      if let icnsData = icnsData(from: icon) {
          let pasteboard = NSPasteboard.general
          pasteboard.clearContents()
          pasteboard.setData(icnsData, forType: NSPasteboard.PasteboardType(rawValue: "com.apple.icns"))
      }
  }
  

• 用LaunchServices拿原生icns数据
  系统文件或已注册类型的文件，用LaunchServices的接口能拿到更原生的.icns数据，比NSImage转的更贴近Finder复制的效果：

  import CoreServices
  
  func icnsDataForFile(at url: URL) -> Data? {
      var iconRef: IconRef?
      let status = LSCopyIconRefForURL(url as CFURL, kLSIconSizeNormal, &iconRef)
      guard status == noErr, let icon = iconRef else { return nil }
      
      var data: CFData?
      if IconRefCopyData(icon, kIconServicesFormatICNS, &data) == noErr {
          return data as Data?
      }
      return nil
  }
  
  // 使用示例
  let fileURL = URL(fileURLWithPath: "/path/to/your/file")
  if let icnsData = icnsDataForFile(at: fileURL) {
      let pasteboard = NSPasteboard.general
      pasteboard.clearContents()
      pasteboard.setData(icnsData, forType: NSPasteboard.PasteboardType(rawValue: "com.apple.icns"))
  }
  

内容的提问来源于stack exchange，提问作者Thomas Tempelmann