未调用 BLE 外设委托

Question

我最近从 Swift 3 升级到了 Swift 4，从 iOS 10.3.3 升级到了 iOS 11.1。

我正在开发一个使用 BLE 进行双向通信的应用程序。工作流程如下：

1. 外围设备 - 广告身份
2. CENTRAL - 接收身份（处理它...）
3. CENTRAL - 响应外围设备
4. 外围设备 - 从中​​央接收响应
5. 完成

我的代码在更新之前运行良好，但现在不行了。在第 4 步结束时，我执行以下行：

peripheral.writeValue(encryptedData!, for: characteristic, type: .withResponse)

这应该调用以下委托方法，但它没有：

public func peripheral(_ peripheral: CBPeripheral, didWriteValueFor descriptor: CBDescriptor, error: Error?) {
        print("Did Write")
        print("Error=\(error?.localizedDescription)")
    }

它还应该（并且正在调用）外围设备上的以下委托方法，但它没有：

public func peripheralManager(_ peripheral: CBPeripheralManager, didReceiveWrite requests: [CBATTRequest]) {
        print("did receive write request")
}

服务和特性设置如下：

let prefs = Preferences()
            let strServiceUUID = prefs.GetString(key: Preferences.PREF_IDENTITY_SERVICE_UUID, defaultVal: "")!
            let strCharacteristicUUID = prefs.GetString(key: Preferences.PREF_IDENTITY_CHARACTERISTIC_UUID, defaultVal: "")!
            print("ServiceUUID=\(strServiceUUID)")
            print("CharacteristicUUID=\(strCharacteristicUUID)")
            mServiceUUID = CBUUID(string: strServiceUUID)
            mCharacterUUID = CBUUID(string: strCharacteristicUUID)
            mCBBluetoothServices = CBMutableService(type: mServiceUUID, primary: true)
            
            //lets configure the data we want to advertise for
            var characteristics : [CBCharacteristic] = []
            
            //let strData : String = "933911"
            //let data = strData.data(using: .utf8)
            let cbProperties: CBCharacteristicProperties = [.read, .write, .notify]
            let cbPermissions: CBAttributePermissions = [.readable, .writeable]
            mIdentityObjectCharacteristic = CBMutableCharacteristic(type: mCharacterUUID,
                                                                    properties: cbProperties,
                                                                    value: nil,
                                                                    permissions: cbPermissions)
            
            
            characteristics.append(mIdentityObjectCharacteristic)
            mCBBluetoothServices.characteristics = characteristics
            mCBPeripheralManager.add(mCBBluetoothServices)

Answer 1

我不确定为什么升级 OS 和 Swift 版本会破坏您的代码，但是在我看来您可能使用了错误的委托方法？

试试这个

func peripheral(CBPeripheral, didWriteValueFor: CBCharacteristic, error: Error?)

而不是这个

func peripheral(CBPeripheral, didWriteValueFor: CBDescriptor, error: Error?)

Answer 2

斯威夫特 4

对于任何类型的更新特性（例如读/写特性），将调用 didUpdateValueFor 委托。

所以，首先检查以下委托方法。

func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?) {
    
    print("didUpdateValueForChar", characteristic)
    
    if let error1 = error{
        
        alertMSG(titleString: "Error", subTitleString: "Found error while read characteristic data, Plase try again", buttonTitle: "OK")
        
        print(error1)
    }
    else{
        
        print("Update Characteristic: ", characteristic)
    }
}

func peripheral(_ peripheral: CBPeripheral, didWriteValueFor characteristic: CBCharacteristic, error: Error?) {
    
    print("Write Characteristic :", characteristic)
}

Answer 3

斯威夫特 5
iOS 13

需要检查的一些事项：

1. 确保将外设的delegate 设置为符合CBPeripheralDelegate 协议的任何控制器（这也应该是需要实现peripheral(_:didWriteValueFor:error:) 方法的同一控制器）。
2. 确保您没有指定 .withoutResponse 写入类型。
3. 正如this other answer 所提到的，有两个非常相似的委托方法具有签名peripheral(_:didWriteValueFor:error:)。确保你正在实施正确的。
   • 写入特征时：
     • writeValue(_:for:type:):

       func writeValue(_ data: Data, 
                       for characteristic: CBCharacteristic, 
                       type: CBCharacteristicWriteType)
       

     • peripheral(_:didWriteValueFor:error:)

       func peripheral(_ peripheral: CBPeripheral, 
                       didWriteValueFor characteristic: CBCharacteristic, 
                       error: Error?)
       

   • 写入描述符时：
     • writeValue(_:for:)

       func writeValue(_ data: Data, 
                       for descriptor: CBDescriptor)
       

     • peripheral(_:didWriteValueFor:error:)

       func peripheral(_ peripheral: CBPeripheral, 
                       didWriteValueFor descriptor: CBDescriptor, 
                       error: Error?)
       

容易混淆2组write和delegate方法。

由于您正在使用：

peripheral.writeValue(encryptedData!, for: characteristic, type: .withResponse) 

write 和 delegate 对的代码应该是这样的：

class BluetoothController: CBCentralManagerDelegate, CBPeripheralDelegate {

    ...
   
    func writeSomething(to characteristic: CBCharacteristic, of peripheral: CBPeripheral) {
        let something = "1234"
        
        NSLog("Writing \(something) to \(characteristic.uuid.uuidString)")
        
        peripheral.delegate = self  // <===== You may have forgotten this?
        peripheral.writeValue(something.data(using: .utf8)!,
                              for: characteristic,
                              type: .withResponse)
    }

    ...

    func peripheral(_ peripheral: CBPeripheral, didWriteValueFor characteristic: CBCharacteristic, error: Error?) {
        if error != nil {
            NSLog("Write error: \(String(describing: error))")
        } else {
            NSLog("Wrote value to \(characteristic.uuid.uuidString)")
        }
    }
}