ios – 在Core Bluetooth Framework中创建可写特性的问题

概述我是Core Bluetooth Framework的新手.我正在开发一个充当外围设备的应用程序.我需要应用程序通知特定值到订阅的中心,并且还通过连接的中心写出特征值.我在创建它时设置了特征值.问题是当我设置要通知或写入的特性属性时显示错误“具有缓存值的特征必须是只读的”.有谁能够帮我 ？ var charValue = characteristicDetail["value"] as Strin 我是Core Bluetooth Framework的新手.我正在开发一个充当外围设备的应用程序.我需要应用程序通知特定值到订阅的中心,并且还通过连接的中心写出特征值.我在创建它时设置了特征值.问题是当我设置要通知或写入的特性属性时显示错误“具有缓存值的特征必须是只读的”.有谁能够帮我 ？

var charValue = characteristicDetail["value"] as String var charPropertIEs:CBCharacteristicPropertIEs = getProperty(characteristicDetail["propertIEs"] as String ) let data = charValue.dataUsingEnCoding(NSUTF8StringEnCoding) var characteristic = CBMutableCharacteristic(type: charID,propertIEs: charPropertIEs,value: data,permissions: CBAttributePermissions.Readable)func getProperty(string:String) -> CBCharacteristicPropertIEs    {    var propertyString:CBCharacteristicPropertIEs?    switch string{    case "r","R":        propertyString = CBCharacteristicPropertIEs.Read    case "w","W":        propertyString = CBCharacteristicPropertIEs.Write    case "n","N":        propertyString = CBCharacteristicPropertIEs.Notify    case "i","I":        propertyString = CBCharacteristicPropertIEs.Indicate    case "rw","wr","WR","RW":        propertyString = CBCharacteristicPropertIEs.Read|CBCharacteristicPropertIEs.Write    case "rn","nr","NR","RN":        propertyString = CBCharacteristicPropertIEs.Read|CBCharacteristicPropertIEs.Notify    case "wn","nw","NW","WN":        propertyString = CBCharacteristicPropertIEs.Write|CBCharacteristicPropertIEs.Notify    default:        propertyString = CBCharacteristicPropertIEs.Read    }    return propertyString!}

解决方法 如果在创建CBMutableCharacteristic时指定非零值,则它是“缓存特征”,并且如错误消息所示,您不能在以后更改该值.

从CBMutableCharacteristic init方法的文档 –

value – The characteristic value to be cached. If nil,the value is dynamic and will be requested on demand.

创建CBMutableCharacteristic时指定nil-在dIDReceiveReadRequest CBPeripheralManagerDelegate方法中请求时提供值.

如果您有已订阅该特性的中心,那么每当值发生变化时,您还应该在CBPeripheralManager上调用updateValue.

请务必阅读Core Bluetooth Programming Guide中的执行常见外设角色任务一节

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