ios - 找不到 != 的重载 - Swift iBeacon

Question

我正在学习可以在这里找到的教程 http://ibeaconmodules.us/blogs/news/14702963-tutorial-swift-based-ibeacon-app-development-with-corelocation-on-apple-ios-7-8

教程的最后一部分建议我将以下代码添加到 View Controller

if(beacons != nil) {
    return beacons!.count
} else {
    return 0
}

在这样做的过程中，我收到了消息标题中发布的错误。看来(根据我有限的知识和研究)这是因为 beacons 变量没有声明为可选的？这可能是我错误地阅读了类似的堆栈溢出帖子。

有人可以解释一下我将如何解决这个问题吗？我的两个类(app delegate和view controller如下)

extension AppDelegate: CLLocationManagerDelegate {
    func sendLocalNotificationWithMessage(message: String!) {
        let notification:UILocalNotification = UILocalNotification()
        notification.alertBody = message
        UIApplication.sharedApplication().scheduleLocalNotification(notification)
    }

    func locationManager(manager: CLLocationManager!,
        didRangeBeacons beacons: [AnyObject],
        inRegion region: CLBeaconRegion!) {
            NSLog("didRangeBeacons");



            let viewController:ViewController = window!.rootViewController as! ViewController
            viewController.beacons = beacons as! [CLBeacon]
            viewController.tableView!.reloadData()


            var message:String = ""

            if(beacons.count > 0) {
                let nearestBeacon:CLBeacon = beacons[0] as! CLBeacon

                if(nearestBeacon.proximity == lastProximity ||
                    nearestBeacon.proximity == CLProximity.Unknown) {
                        return;
                }
                lastProximity = nearestBeacon.proximity;

                switch nearestBeacon.proximity {
                case CLProximity.Far:
                    message = "You are far away from the beacon"
                case CLProximity.Near:
                    message = "You are near the beacon"
                case CLProximity.Immediate:
                    message = "You are in the immediate proximity of the beacon"
                case CLProximity.Unknown:
                    return
                }
            } else {
                message = "No beacons are nearby"
            }

            NSLog("%@", message)
            sendLocalNotificationWithMessage(message)
    }

    func locationManager(manager: CLLocationManager!,
        didEnterRegion region: CLRegion!) {
            manager.startRangingBeaconsInRegion(region as! CLBeaconRegion)
            manager.startUpdatingLocation()

            NSLog("You entered the region")
            sendLocalNotificationWithMessage("You entered the region")
    }

    func locationManager(manager: CLLocationManager!,
        didExitRegion region: CLRegion!) {
            manager.stopRangingBeaconsInRegion(region as! CLBeaconRegion)
            manager.stopUpdatingLocation()

            NSLog("You exited the region")
            sendLocalNotificationWithMessage("You exited the region")
    }
}

View Controller

class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {

    @IBOutlet var tableView: UITableView?
    var beacons: [CLBeacon] = []


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

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


}
extension ViewController: UITableViewDataSource {


    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {

            if(beacons != nil) {
                return beacons!.count
            } else {
                return 0
            }
    }

    func tableView(tableView: UITableView,
        cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
            var cell:UITableViewCell? =
            tableView.dequeueReusableCellWithIdentifier("MyIdentifier") as? UITableViewCell

            if(cell == nil) {
                cell = UITableViewCell(style: UITableViewCellStyle.Subtitle,
                    reuseIdentifier: "MyIdentifier")
                cell!.selectionStyle = UITableViewCellSelectionStyle.None
            }

            let beacon:CLBeacon = beacons[indexPath.row]
            var proximityLabel:String! = ""

            switch beacon.proximity {
            case CLProximity.Far:
                proximityLabel = "Far"
            case CLProximity.Near:
                proximityLabel = "Near"
            case CLProximity.Immediate:
                proximityLabel = "Immediate"
            case CLProximity.Unknown:
                proximityLabel = "Unknown"
            }

            cell!.textLabel!.text = proximityLabel

            let detailLabel:String = "Major: \(beacon.major.integerValue), " +
                "Minor: \(beacon.minor.integerValue), " +
                "RSSI: \(beacon.rssi as Int), " +
            "UUID: \(beacon.proximityUUID.UUIDString)"
            cell!.detailTextLabel!.text = detailLabel

            return cell!
    }
}

extension ViewController: UITableViewDelegate {

}

Answer 1

在您的代码中，beacons 似乎不是可选值。您可以删除整个支票，然后再向前看。