value = (null)是什么意思?

Question

<CBService: 0x1702622c0 Peripheral = <CBPeripheral: 0x1780bc680 identifier = 17D7A5C8-BAB5-82E6-826E-BE80A994687A, Name = "Bluegiga CR Demo", state = connected>, Primary = YES, UUID = 0BD51666-E7CB-469B-8E4D-2742F1BA77CC>
Notification began on <CBCharacteristic: 0x170086e50 UUID = E7ADD780-B042-4876-AAE1-112855353CC1, Value = (null), Properties = 0x28, Notifying = YES, Broadcasting = NO>

value = (null)是什么意思?我不能使用writeValue?我需要使用updateValue?

Answer 1

CBCharacteristic有几个@properties…https://developer.apple.com/library/ios/documentation/CoreBluetooth/Reference/CBCharacteristic_Class/translated_content/CBCharacteristic.html

一种是value，属于NSData型。

如果this为null，则表示其中没有数据。