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如何轻松调整Swift代码中的网络DNS设置，提升上网速度与安全？

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在Swift开发中，网络DNS的设置对于应用的性能和安全性有着重要的影响。通过合理调整DNS设置，可以提升上网速度和增强网络安全。以下是一些关于如何在Swift代码中调整网络DNS设置的方法和技巧。

了解DNS及其作用

DNS（域名系统）是将易于记忆的域名转换为IP地址的系统。当我们在浏览器中输入一个网址时，DNS服务器会帮助我们找到对应的IP地址，从而访问到网站。

DNS的作用：

  1. 解析域名：将域名转换为IP地址。
  2. 提高网络速度：通过缓存DNS记录，减少查询时间。
  3. 增强安全性：通过DNS过滤和DNS劫持防护，提高网络安全。

调整DNS设置的方法

在Swift中，我们可以通过以下几种方式调整网络DNS设置：

1. 使用NetworkReachability类

NetworkReachability类可以帮助我们检测网络连接状态，并调整DNS设置。

import SystemConfiguration

func setupNetworkReachability() {
    var flags: SCNetworkReachabilityFlags = []
    if !SCNetworkReachabilityCreateWithAddress(nil, "www.google.com", &flags) {
        print("无法创建网络可达性对象")
        return
    }

    if flags.contains(.reachable) {
        print("网络可达")
        if flags.contains(.isDirect) {
            print("直接连接")
        } else {
            print("通过代理连接")
        }
        
        // 获取当前DNS服务器
        let currentDNSServers = getDNSServers()
        print("当前DNS服务器：\(currentDNSServers)")
        
        // 设置新的DNS服务器
        let newDNSServers = ["8.8.8.8", "8.8.4.4"]
        setDNSServers(newDNSServers)
        print("新的DNS服务器：\(getDNSServers())")
    } else {
        print("网络不可达")
    }
}

func getDNSServers() -> [String] {
    var addresses = [String]()
    var zeroAddress = sockaddr_in()
    zeroAddress.sin_len = UInt8(MemoryLayout.size(ofValue: zeroAddress))
    zeroAddress.sin_family = sa_family_t(AF_INET)

    guard let defaultRouteReachability = withUnsafePointer(to: &zeroAddress, {
        $0.withMemoryRebound(to: sockaddr.self, capacity: 1) {
            SCNetworkReachabilityCreateWithAddress(nil, $0)
        }
    }) else {
        return addresses
    }

    var flags: SCNetworkReachabilityFlags = []
    if !SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags) {
        return addresses
    }

    if flags.contains(.reachable) {
        var zeroLengthAddress = [CChar](repeating: 0, count: Int(MemoryLayout.size(ofValue: zeroAddress)))
        zeroLengthAddress.withUnsafeMutableBytes { zeroLengthAddressPointer in
            if !SCNetworkReachabilityGetAddress(defaultRouteReachability, &zeroLengthAddressPointer) {
                return addresses
            }
        }

        var address = sockaddr_in()
        address.sin_len = UInt8(MemoryLayout.size(ofValue: address))
        address.sin_family = sa_family_t(AF_INET)

        withUnsafePointer(to: &address) {
            $0.withMemoryRebound(to: sockaddr.self, capacity: 1) {
                addresses.append("\(inet_ntoa($0.sin_addr))")
            }
        }
    }

    return addresses
}

func setDNSServers(_ servers: [String]) {
    var flags: SCNetworkReachabilityFlags = []
    if !SCNetworkReachabilityCreateWithAddress(nil, "www.google.com", &flags) {
        print("无法创建网络可达性对象")
        return
    }

    if flags.contains(.reachable) {
        var zeroAddress = sockaddr_in()
        zeroAddress.sin_len = UInt8(MemoryLayout.size(ofValue: zeroAddress))
        zeroAddress.sin_family = sa_family_t(AF_INET)

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

        var flags: SCNetworkReachabilityFlags = []
        if !SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags) {
            return
        }

        if flags.contains(.reachable) {
            var zeroLengthAddress = [CChar](repeating: 0, count: Int(MemoryLayout.size(ofValue: zeroAddress)))
            zeroLengthAddress.withUnsafeMutableBytes { zeroLengthAddressPointer in
                if !SCNetworkReachabilityGetAddress(defaultRouteReachability, &zeroLengthAddressPointer) {
                    return
                }
            }

            var address = sockaddr_in()
            address.sin_len = UInt8(MemoryLayout.size(ofValue: address))
            address.sin_family = sa_family_t(AF_INET)

            withUnsafePointer(to: &address) {
                $0.withMemoryRebound(to: sockaddr.self, capacity: 1) {
                    var status: SCNetworkReachabilityFlags = []
                    if !SCNetworkReachabilitySetDNSServers(defaultRouteReachability, $0, servers) {
                        print("设置DNS服务器失败")
                    } else {
                        print("设置DNS服务器成功")
                    }
                }
            }
        }
    }
}

2. 使用CFNetwork框架

CFNetwork框架提供了更简单的方法来调整DNS设置。

import CFNetwork

func setupNetworkDNS() {
    let defaultConfig = CFNetworkCopyCurrentNetworkInfo(nil)
    let keys: [CFString] = [kCFNetworkConfigurationKeysDNSServers as CFString]
    let newDNSServers = [kCFNetworkConfigurationKeysDNSServers as CFString: [kCFNetworkConfigurationKeysDNSServers as CFString: ["8.8.8.8", "8.8.4.4"]]]

    CFNetworkSetNetworkInfo(defaultConfig!, keys, newDNSServers)
    print("新的DNS服务器：\(CFNetworkCopyDNSServers(defaultConfig!))")
}

总结

通过以上方法，我们可以在Swift代码中轻松调整网络DNS设置，从而提升上网速度和增强网络安全。在实际开发中，可以根据需求选择合适的方法进行设置。

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