IOS BLE通讯写值；

Question

我正在编写我的第一个 IOS 应用程序，用于与 Bluegiga BLE 芯片通信。我需要读取和写入值。我遇到的问题是，我无法在第一次运行程序时写入值。我没有收到任何错误。它显示写入当前值的最后一个值。当我重新运行程序时，正确的值已正确更新。它延迟了我的项目。任何建议都会有很大帮助。我正在使用以下代码片段。

CBPeripheral        *servicePeripheral;
NSData              *readIndex;
CBCharacteristic    *readIdxCharacteristic;

[servicePeripheral writeValue:readIndex forCharacteristic:readIdxCharacteristic type:CBCharacteristicWriteWithResponse];

- (void) peripheral:(CBPeripheral *)peripheral didWriteValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error
{

    if ([characteristic isEqual:readIdxCharacteristic] ){
        [peripheral readValueForCharacteristic:readIdxCharacteristic];
        NSLog(@"Read Index Characteristic Written Check%@",characteristic.value);
    }
}

Answer 1

您的问题是，您在调用readValueForCharacteristic后立即访问characteristic.value，但Core-Bluetooth需要一些时间才能联系外设，请求特征值和外设回复的值。

如果您引用 documentation for this method你会看到 -

Discussion

When you call this method to read the value of a characteristic, the peripheral calls the peripheral:didUpdateValueForCharacteristic:error: method of its delegate object. If the value of the characteristic is successfully retrieved, you can access it through the characteristic’s value property.

因此，您需要在 didUpdateValueForCharacteristic: CBPeripheral 委托(delegate)方法中访问 characteristic.value