Swift 中 IPv6 网络上的网络连接检查崩溃

Question

我最近因为与 IPv6 不兼容而遭到拒绝。调用以下代码时，应用程序导致崩溃。我怀疑崩溃是因为它使用了SCNetworkReachabilityCreateWithAddress，而 Apple 建议不要再使用它。

谁能帮我把下面的代码与 IPv6 和 IPv4 兼容？

代码

import Foundation
import SystemConfiguration

public class Reachability {

    class func isConnectedToNetwork() -> Bool {

        var zeroAddress = sockaddr_in(sin_len: 0, sin_family: 0, sin_port: 0, sin_addr: in_addr(s_addr: 0), sin_zero: (0, 0, 0, 0, 0, 0, 0, 0))
        zeroAddress.sin_len = UInt8(sizeofValue(zeroAddress))
        zeroAddress.sin_family = sa_family_t(AF_INET)

        let defaultRouteReachability = withUnsafePointer(&zeroAddress) {
            SCNetworkReachabilityCreateWithAddress(nil, UnsafePointer($0)).takeRetainedValue()
        }

        var flags: SCNetworkReachabilityFlags = 0
        if SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags) == 0 {
            return false
        }

        let isReachable = (flags & UInt32(kSCNetworkFlagsReachable)) != 0
        let needsConnection = (flags & UInt32(kSCNetworkFlagsConnectionRequired)) != 0

        return isReachable && !needsConnection
    }

}

代码来源：

Check for internet connection availability in Swift

确实加载了视图代码调用：

if Reachability.isConnectedToNetwork() == false
{
      // internet is down
      let error = NSError(domain: "", code: 3, userInfo: nil)           let alertView = createDefaultAlertError(error.code)
      let tryAgainAction = UIAlertAction(title: ClassGeneralMessages().userMessageTryAgain, style: UIAlertActionStyle.Default) { (UIAlertAction) in                
}
else
{
     // internet is ok
     // run more code here
}

Answer 1

来自Apple's documentation on supporting IPv6-only networks：

无需预检即可连接

可达性 API（请参阅 SCNetworkReachability Reference）用于在识别连接问题后进行诊断。许多应用程序错误地使用这些 API 来主动检查 Internet 连接，方法是调用 SCNetworkReachabilityCreateWithAddress 方法并向其传递 IPv4 地址 0.0.0.0，这表明网络上有路由器。但是，存在路由器并不能保证存在 Internet 连接。一般来说，避免预检网络可达性。只需尝试建立连接并优雅地处理故障。如果您必须检查网络可用性，请避免调用SCNetworkReachabilityCreateWithAddress 方法。调用 SCNetworkReachabilityCreateWithName 方法并改为传递一个主机名。

您的应用似乎在做它不建议做的两件事：

1. 使用可达性 API 执行预检，而不是仅在出现连接问题时。
2. 将 IPv4 文字而不是主机名传递给可达性 API。

为了解决这个问题，我建议不要预先检查网络连接，而是处理网络代码中的错误。

Answer 2

您遇到了崩溃，因为您在应该在主 UI 线程中运行的代码中显示了一个警报。将您的 UI 代码放入主 UI 线程的 dispatch_async 中，它应该可以解决问题。

dispatch_async(dispatch_get_main_queue(),
{
   let error = NSError(domain: "", code: 3, userInfo: nil)           let alertView = createDefaultAlertError(error.code)
      let tryAgainAction = UIAlertAction(title: ClassGeneralMessages().userMessageTryAgain, style: UIAlertActionStyle.Default) { (UIAlertAction) in }
})

Answer 3

试试这个：

class func isConnectedToNetwork() -> Bool
        {
            var zeroAddress = sockaddr_in6()
            zeroAddress.sin6_len = UInt8(MemoryLayout.size(ofValue: zeroAddress))
            zeroAddress.sin6_family = sa_family_t(AF_INET6)

            let defaultRouteReachability = withUnsafePointer(to: &zeroAddress) {
                $0.withMemoryRebound(to: sockaddr.self, capacity: 1) {zeroSockAddress in
                    SCNetworkReachabilityCreateWithAddress(nil, zeroSockAddress)
                }
            }

            var flags = SCNetworkReachabilityFlags()
            if !SCNetworkReachabilityGetFlags(defaultRouteReachability!, &flags) {
                return false
            }
            let isReachable = (flags.rawValue & UInt32(kSCNetworkFlagsReachable)) != 0
            let needsConnection = (flags.rawValue & UInt32(kSCNetworkFlagsConnectionRequired)) != 0
            return (isReachable && !needsConnection)
        }

Answer 4

    func isConnectedToNetwork() -> Bool {
    
    var zeroAddress = sockaddr_in()
    zeroAddress.sin_len = UInt8(MemoryLayout.size(ofValue: zeroAddress))
    zeroAddress.sin_family = sa_family_t(AF_INET)
    
    
    let defaultRouteReachability = withUnsafePointer(to: &zeroAddress) {
        $0.withMemoryRebound(to: sockaddr.self, capacity: 1) {zeroSockAddress in
            SCNetworkReachabilityCreateWithAddress(nil, zeroSockAddress)
        }
    }
    //Commented code only work upto iOS Swift 2.3
    //    let defaultRouteReachability = withUnsafePointer(to: &zeroAddress) {
    //
    //        SCNetworkReachabilityCreateWithAddress(nil, UnsafePointer($0))
    //    }
    
    var flags = SCNetworkReachabilityFlags()
    
    if !SCNetworkReachabilityGetFlags(defaultRouteReachability!, &flags) {
        return false
    }
    
    let isReachable = (flags.rawValue & UInt32(kSCNetworkFlagsReachable)) != 0
    let needsConnection = (flags.rawValue & UInt32(kSCNetworkFlagsConnectionRequired)) != 0
    return (isReachable && !needsConnection)
}