Ios Swift WebView-无连接模式

我目前正在使用UIWebView在控制器中显示URL中的内容，我想知道，如果没有连接到设备，如何显示消息或显示警报对话框，您需要internet连接才能显示内容

我有以下代码：

import UIKit

class SecondView: UICollectionViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        let myWebView:UIWebView = UIWebView(frame: CGRectMake(0, 0, UIScreen.mainScreen().bounds.width, UIScreen.mainScreen().bounds.height))
        myWebView.loadRequest(NSURLRequest(URL: NSURL(string: "http://www.google.com")!))
        self.view.addSubview(myWebView)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }

}

---

谢谢大家!

以下是完整的工作代码：

import UIKit
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) ? true : false
}

}


class SecondView: UICollectionViewController {

override func viewDidLoad() {
    super.viewDidLoad()


}

override func viewDidAppear(animated: Bool) {
    if Reachability.isConnectedToNetwork() {

        let myWebView:UIWebView = UIWebView(frame: CGRectMake(0, 0, UIScreen.mainScreen().bounds.width, UIScreen.mainScreen().bounds.height))
        myWebView.loadRequest(NSURLRequest(URL: NSURL(string: "http://www.google.com")!))
        self.view.addSubview(myWebView)

    } else {

        var alert = UIAlertController(title: "Alert", message: "you need internet connection to display the content", preferredStyle: UIAlertControllerStyle.Alert)
        alert.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.Default, handler: nil))
        self.presentViewController(alert, animated: true, completion: nil)
        }
    }

}

---

它没有给出错误，但是应用程序崩溃了。我把基础和系统配置添加到“链接框架和库”……让我看看你的崩溃日志，你从我的代码中更改了类名吗？我更新了答案中的类名，请检查。很高兴帮助您。：）