没有网络连接时显示警报

Question

如何通知用户 swift 3 没有网络连接。我尝试了很多解决方案，但到目前为止都没有奏效。我不是在寻找网络连接的速度

Answer 1

有很多资源展示了如何检查互联网连接。例如，来自this。

    func isInternetAvailable() -> 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)
            }
        }

        var flags = SCNetworkReachabilityFlags()
        if !SCNetworkReachabilityGetFlags(defaultRouteReachability!, &flags) {
            return false
        }
        let isReachable = flags.contains(.reachable)
        let needsConnection = flags.contains(.connectionRequired)
        return (isReachable && !needsConnection)
    }

    func showAlert() {
        if !isInternetAvailable() {
            let alert = UIAlertController(title: "Warning", message: "The Internet is not available", preferredStyle: .alert)
            let action = UIAlertAction(title: "Dismiss", style: .default, handler: nil)
            alert.addAction(action)
            present(alert, animated: true, completion: nil)
        }
    }

你需要导入：

import Foundation
import SystemConfiguration