检测正确的USB设备是否连接 - Swift

Question

使用最新的SwiftUI和Xcode 13，具有OS 12.3+的目标，我需要检测到特定的USB驱动器是否连接到机器。如果是，我需要将变量设置为true，如果将其删除为false。

我还没有找到任何更新的代码示例来执行此操作，而且Apple的文档是... Apple的文档。

我将其与以下代码一起使用，该代码将信息打印到控制台。它仅在指定的volumeUID上寻找USB设备，但是由于它确实是旧的C代码，我希望有人可以共享一种更新的方法，这也可以让我设置一个变量，而不是仅仅打印到安慰。

import DiskArbitration
import Foundation
import IOKit

class USB_Helper: ObservableObject {

    @Published var usbConnected: Bool = false

    init() {
        print("USB Helper Initialized")
        tryUSB()
    }

    func tryUSB() {
        let validation: CFDictionary = [
            "DADeviceProtocol":"USB",
            "DAVolumeUUID": CFUUIDCreateFromString(kCFAllocatorDefault, "F0672BD0-1FA9-3567-452F-322138E12C35" as CFString)!
        ] as CFDictionary

        let diskAppearedCallback: DADiskAppearedCallback = {
            disk,
            context in print(
                "Disk appeared:",
                disk
            )
            printDiskInfo(
                disk
            )
        }

        let diskDisappearedCallback: DADiskDisappearedCallback = {
            disk,
            context in print(
                "Disk disappeared:",
                disk
            )
            printDiskInfo(
                disk
            )
        }

        let runloop = RunLoop.current
        let session = DASessionCreate(kCFAllocatorDefault)!

        func printDiskInfo(_ disk: DADisk) {
            guard let description = DADiskCopyDescription(disk) as? [String: Any] else {
                fatalError()
            }
            print(description)
        }

        DARegisterDiskAppearedCallback(
            session,
            validation,
            diskAppearedCallback,
            nil
        )

        DARegisterDiskDisappearedCallback(
            session,
            validation,
            diskDisappearedCallback,
            nil
        )

        DASessionScheduleWithRunLoop(
            session,
            runloop.getCFRunLoop(),
            CFRunLoopMode.defaultMode.rawValue
        )

    } // End Func

} // End Class

Answer 1

答案是，似乎没有办法从回调内设置变量，但是解决方案非常简单。

1. 您想发送一个
2. 要捕获该通知的通知，并运行驻留在Tryusb函数之外的函数以设置Bool变量

以下是要设置变量的函数：

@objc func usbTrue() {
    self.usbConnected = true
    print("USB Connected")
}

@objc func usbFalse() {
    self.usbConnected = false
    print("USB Disconnected")
}

以下是通知对回调的修改：

let diskAppearedCallback: DADiskAppearedCallback = {
            disk,
            context in print(
                "Disk appeared:",
                disk
            )
            NotificationCenter.default.post(name: Notification.Name("DiskAppeared"), object: disk)
        }

        NotificationCenter.default.addObserver(self, selector: #selector(usbTrue), name: Notification.Name("DiskAppeared"), object: nil)

        let diskDisappearedCallback: DADiskDisappearedCallback = {
            disk,
            context in print(
                "Disk disappeared:",
                disk
            )
            NotificationCenter.default.post(name: Notification.Name("DiskDisappeared"), object: disk)
        }
        
        NotificationCenter.default.addObserver(self, selector: #selector(usbFalse), name: Notification.Name("DiskDisappeared"), object: nil)

i真的希望这篇文章对他人有所帮助，因为我花了很长时间才能弄清楚这一点。祝你好运！