核心蓝牙CBCentralManager在Mac上始终将状态报告为“未知"

问题描述

我一般都不熟悉Swift和Mac/iOs编程.我正在使用Xcode 7.3在具有BLE支持并已打开蓝牙的Macbook Pro上运行此示例.

I'm new to Swift and Mac/iOs programming in general. I'm running this sample on a Macbook Pro with BLE support and with Bluetooth turned on, using Xcode 7.3.

import Foundation
import CoreBluetooth

func printState(state: CBCentralManagerState) {
    switch state {
    case CBCentralManagerState.PoweredOn:
        print("Powered on")
    case CBCentralManagerState.PoweredOff:
        print("Powered off")
    case CBCentralManagerState.Resetting:
        print("Resetting")
    case CBCentralManagerState.Unauthorized:
        print("Unauthorized")
    case CBCentralManagerState.Unknown:
        print("Unknown")
    default:
        print ("Unsupported")
    }

}

var myCentralManager = CBCentralManager(delegate:nil, queue:nil)
while true {
    printState(myCentralManager.state)
    sleep(1)
}

即使在几分钟后，该代码也会反复打印出未知"字样.我也尝试过设置一个委托，但是didUpdateState回调没有被调用.我还尝试从命令行和Swift解释器运行此命令，并获得相同的结果.

The code prints out "Unknown" over and over, even after many minutes. I've also tried setting up a delegate but the didUpdateState callback doesn't called. I've also tried to run this from the command line and Swift interpreter and get the same result.

我一定错过了一些非常基本的东西.如何获得报告CBCentralManager已打开电源的信息?

I must be missing something very basic. How can I get it to report that the CBCentralManager is powered on?

推荐答案

据我所知，如果您不使用文档中列出的两个初始值设定项之一，那么结果就是-您想使用其中一个:

Near as I can tell, if you don't use one of the two initializers listed in the documentation, this is the result -- you want to use either:

init(delegate:queue:)

或:

init(delegate:queue:options:)

如果您致电，Xcode不会抱怨:

Xcode doesn't complain if you just call:

CBCentralManager()

但是，如果您这样做，似乎您将无限期地停留在CBCentralManagerState.Unknown中.

but if you do that, it seems like you'll stay in CBCentralManagerState.Unknown indefinitely.

如果要进行实验，请创建一个操场并粘贴此代码，然后尝试使用我列出的两个初始化变量:

If you want to experiment, make a playground and paste this code, and try it with the two initializer variants I've listed:

import Cocoa
import CoreBluetooth
import XCPlayground

@objc
public class BluetoothWatcher: NSObject, CBCentralManagerDelegate {
    var cbcm: CBCentralManager!;
    var timer: NSTimer!;

    override init() {
        super.init();

        /*:
            When you initialize a central manager, the delegate seems important. If you comment out the initializer with the delegate and uncomment the other one, it'll stay in state unknown indefinitely.
        */
        //cbcm = CBCentralManager(delegate: self, queue:nil);
        cbcm = CBCentralManager();

        checkStateInOneSecond();
    }

    public func centralManagerDidUpdateState(central: CBCentralManager) {
        print( "State updated: \(stateString())" );
    }

    func checkStateInOneSecond() {
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (Int64)(1 * NSEC_PER_SEC)), dispatch_get_main_queue(), {
            self.checkState();
        });
    }

    public func checkState() {
        print( "Timer fired, state: \(stateString())" );
        checkStateInOneSecond();
    }

    func stateString() -> String {
        switch(cbcm.state) {
        case .Resetting:
            return "resetting"
        case .PoweredOn:
            return "powered on";
        case .PoweredOff:
            return "powered off";
        case .Unknown:
            return "unknown";
        case .Unsupported:
            return "unsupported";
        case .Unauthorized:
            return "unauthorized";
        }
    }
}


XCPlaygroundPage.currentPage.needsIndefiniteExecution = true;
var watcher = BluetoothWatcher();

您将看到与委托有关的内容，它从Unknown开始，并且几乎立即以状态更改为PoweredOn的方式调用了该委托，并且随后的每个计时器触发都显示PoweredOn.

You'll see with the delegate, it starts in Unknown, and almost immediately the delegate gets called with a state change to PoweredOn, and every subsequent timer fire shows PoweredOn.

在没有委托的情况下使用空的初始化程序执行相同的操作，并且永远不会调用委托方法(毫不奇怪)，并且计时器触发将继续显示Unknown.

Do the same thing without the delegate, with the empty initializer, and the delegate method will never be called (no surprise) and the timer fires will continue to show Unknown.

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