[英]ios ble “Characteristic User Description”
Trying to retrieve readable information from an characteristics by using the function: 通过使用以下函数尝试从特征中检索可读信息:
peripheral.discoverDescriptors(for: characteristic)
Later the delegate method: 后来的委托方法:
func peripheral(_ peripheral: CBPeripheral, didDiscoverDescriptorsFor characteristic: CBCharacteristic, error: Error?)
is called but how can I get the string description? 被称为,但如何获得字符串描述? When I read the value from the descriptors it's always
nil
. 当我从描述符中读取值时,它始终为
nil
。
let descriptors = characteristic.descriptors! as [CBDescriptor]
for descriptor in descriptors {
print("\(#function): descriptor = \(descriptor) UUID = \(descriptor.uuid) value = \(descriptor.value)")
}
However, if I'm browsing and connecting with an BLE scanner it can read the characteristic human readable descriptors. 但是,如果我正在浏览并连接BLE扫描仪,它可以读取人类可读的特征描述符。
Reading descriptors is a two-step process, much like discovering and then reading characteristics. 读取描述符是一个两步过程,非常类似于发现然后读取特征。
Try: 尝试:
public func peripheral(_ peripheral: CBPeripheral, didDiscoverDescriptorsFor characteristic: CBCharacteristic, error: Error?) {
guard let descriptors = characteristic.descriptors else { return }
for descr in descriptors {
peripheral.readValue(for: descr)
}
}
And then fill in the blanks of: 然后填写以下内容:
public func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor descriptor: CBDescriptor, error: Error?) {
switch descriptor.uuid.uuidString {
case CBUUIDCharacteristicExtendedPropertiesString:
guard let properties = descriptor.value as? NSNumber else {
break
}
print(" Extended properties: \(properties)")
case CBUUIDCharacteristicUserDescriptionString:
guard let description = descriptor.value as? NSString else {
break
}
print(" User description: \(description)")
case CBUUIDClientCharacteristicConfigurationString:
guard let clientConfig = descriptor.value as? NSNumber else {
break
}
print(" Client configuration: \(clientConfig)")
case CBUUIDServerCharacteristicConfigurationString:
guard let serverConfig = descriptor.value as? NSNumber else {
break
}
print(" Server configuration: \(serverConfig)")
case CBUUIDCharacteristicFormatString:
guard let format = descriptor.value as? NSData else {
break
}
print(" Format: \(format)")
case CBUUIDCharacteristicAggregateFormatString:
print(" Aggregate Format: (is not documented)")
default:
break
}
}
The string constants and the associated data types came from the overview table here . 字符串常量和关联的数据类型来自此处的概览表。
In my (limited) experience, descriptors don't reveal anything particularly interesting. 以我的(有限的)经验,描述符没有揭示出任何特别有趣的东西。
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