CBCharacteristic

Identifying a Characteristic

@property(readonly, nonatomic) CBUUID *UUID
@property(weak, readonly, nonatomic) CBService *service

Accessing Characteristic Data

@property(retain, readonly) NSData *value//例如体温检测服务，value为温度
@property(retain, readonly) NSArray *descriptors//CBDescriptor对象数组，value外的其他值等
@property(readonly, nonatomic) CBCharacteristicProperties properties//The properties of a characteristic determine how the characteristic’s value and descriptors can be used and accessed. 
@property(readonly) BOOL isNotifying
@property(readonly) BOOL isBroadcasted//IOS8以后不使用

Constants

typedef enum {
   CBCharacteristicPropertyBroadcast  = 0x01 ,
   CBCharacteristicPropertyRead  = 0x02 ,
   CBCharacteristicPropertyWriteWithoutResponse  = 0x04 ,
   CBCharacteristicPropertyWrite  = 0x08 ,
   CBCharacteristicPropertyNotify  = 0x10 ,
   CBCharacteristicPropertyIndicate  = 0x20 ,
   CBCharacteristicPropertyAuthenticatedSignedWrites  = 0x40 ,
   CBCharacteristicPropertyExtendedProperties  = 0x80 ,
   CBCharacteristicPropertyNotifyEncryptionRequired  = 0x100 ,
   CBCharacteristicPropertyIndicateEncryptionRequired  = 0x200 ,
} CBCharacteristicProperties;

Values representing the possible properties of a characteristic. Since characteristic properties can be combined, a characteristic may have multiple property values set. 

1.read，调用readValueForCharacteristic方法，然后数据更新的时候会调用peripheral:didUpdateValueForCharacteristic:error:方法。此时读取value值即可。

2.write，使用 writeValue:forCharacteristic:type:方法写数据。type值表明是否有response。（没有response的比有response的数值可以更长？）