Question

我有一个返回某些系统值的函数。它在Swift 2.2中运行良好，我刚刚升级到Xcode 8和Swift 3，现在它失败了。

func ioPlatExpertDevString(_ property: String) -> String {
    // Start tapping in to the IO Service
    let ioPlatformExpertDevice:io_service_t? = IOServiceGetMatchingService(kIOMasterPortDefault, IOServiceMatching("IOPlatformExpertDevice"))

    var sAnswer = "Not Found"
    let cfAnswer:AnyObject! = IORegistryEntryCreateCFProperty(ioPlatformExpertDevice!, "\(property)" as CFString!, kCFAllocatorDefault, 0).takeRetainedValue()
    if (cfAnswer != nil) {
        let nsAnswer = (cfAnswer as! NSString)
        sAnswer = nsAnswer.uppercased
    }

    // Close the IO Service
    IOObjectRelease(ioPlatformExpertDevice!)

    return sAnswer
}

之前，我正在使用＆＃34; CFData＆＃34;而不是＆＃34; AnyObject＆＃34;。它构建良好，但在运行时，我收到以下错误：

无法转换类型＆＃39; __ NSCFData＆＃39;的值（0x7fff7b833ec0）到＆＃39; NSString＆＃39; （0x7fff7ac32038）。

Answer 1

<强>替换

let nsAnswer = (cfAnswer as! NSString)

要

let nsAnswer = NSString(data: cfAnswer as! Data, encoding: String.Encoding.utf8.rawValue)

Answer 2

除非编译器告诉您这样做，否则请不注释类型。

例如IOServiceGetMatchingService会返回一个非可选的io_service_t，您的可选注释会使其更糟。

IORegistryEntryCreateCFProperty返回Unmanaged<CFTypeRef>!不需要注释，字符串插值和强制解包可选的强制转换。

CFTypeRef可以桥接到本机Swift类型。

如果返回类型为(NS)Data，则它在以前的版本中最不可能使用。

如果后者可以转换为String，则此代码会考虑Data和String。

func ioPlatExpertDevString(_ property: String) -> String {
  // Start tapping in to the IO Service
  let ioPlatformExpertDevice = IOServiceGetMatchingService(kIOMasterPortDefault, IOServiceMatching("IOPlatformExpertDevice"))

  var sAnswer = "Not Found"
  let cfAnswer = IORegistryEntryCreateCFProperty(ioPlatformExpertDevice, property as CFString, kCFAllocatorDefault, 0).takeRetainedValue()
  if let cfData = cfAnswer as? Data, let answer = String(data:cfData, encoding:.utf8) {
    sAnswer = answer.uppercased()
  } else if let answer = cfAnswer as? String {
    sAnswer = answer.uppercased()
  }
  // Close the IO Service
  IOObjectRelease(ioPlatformExpertDevice)
  return sAnswer
}

Answer 3

有关Swift的最新版本：

String(decoding: data, as: UTF8.self)

在Swift 3中将NSData转换为NSString？

3 个答案: