iOS 从 BLE 设备读取数据答案

【问题标题】：iOS reading data from BLE deviceiOS 从 BLE 设备读取数据
【发布时间】：2013-08-21 09:08:50
【问题描述】：

我正在尝试从 BLE 设备读取数据，但不断收到权限错误。演示项目可以在这里找到：https://github.com/sergiomtzlosa/CoreBluetooth-Demo（请记住 - 我的代码与这个有点不同）。

连接和读取值一般没有问题，但有一些特征（这是必不可少的）给予权限错误。

控制台日志：更新错误！！！特征：“未知（）” 出现错误：“不允许读取”。

因此，当我从该特征订阅或读取数据时，它每次都会向我发送 NULL（可能的原因：没有读取权限）。

控制台日志：特征：“未知 ()”-> 具有值： (null)

这是一段代码：

//Action on discovering services
- (void)peripheral:(CBPeripheral *)peripheral didDiscoverServices:(NSError *)error
{

if (error) 
{
    NSLog(@"Discovered services for %@ with error: %@", peripheral.name, [error localizedDescription]);
    return;
}
for (CBService *service in peripheral.services) {

    NSLog(@"Discovereddddddddddd service %@", service.UUID);
    [testPeripheral discoverCharacteristics:nil  forService:service];
}
 NSLog(@"didDiscoverServicesEnd");
}

//Action on discovered characteristics
- (void)peripheral:(CBPeripheral *)peripheral
didDiscoverCharacteristicsForService:(CBService *)service error:(NSError *)error {
NSLog(@"didDiscoverCharacteristicsForService!");
for (CBCharacteristic *characteristic in service.characteristics) {
    NSLog(@"Discovered characteristic %@", characteristic.UUID);
    NSLog(@"---------------------------------------------------");
    NSLog(@"Reading value for characteristic %@", characteristic.UUID);
    [peripheral readValueForCharacteristic:characteristic];
    NSLog(@"+++++++++++++++++++++++++++++++++++++++++++++++++++");
    [peripheral setNotifyValue:YES forCharacteristic:characteristic];
    }
}

//Action on reading value
- (void)peripheral:(CBPeripheral *)peripheral 
didUpdateValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error{
if (error){
    NSLog(@"Update error!!! Characteristic: %@ with error: %@", characteristic.UUID, [error localizedDescription]);
    return;
}else{
    NSData *data = characteristic.value;
    NSString *str = [NSString stringWithUTF8String:[data bytes]];
    NSLog(@"Characteristic: %@ -> with value: %@", characteristic.UUID, str);
}
}

怎么了？有没有办法克服这个问题？

【问题讨论】：

你确定这些是可读的特征吗？从外设端向我们展示特征初始化代码。
该特性似乎不允许阅读。也许要先配对？
已经配对。我没有外设端的驱动代码，还想去拿。

标签： ios bluetooth core-bluetooth

【解决方案1】：

外围设备是嵌入式设备还是另一个 iOS 设备。我已经看到必须将外围设备的特征显式配置为具有读取权限的地方。仅仅因为你发现了一个特征并不意味着你可以阅读它。

【讨论】：

【解决方案2】：

您必须检查您是否有访问该值的权限，该权限是在您初始化 CBCharacteristic 时设置的

"特征值权限表示特征值的读取、写入和加密权限的值。

typedef enum {
   CBAttributePermissionsReadable = 0x01,
   CBAttributePermissionsWriteable = 0x02,
   CBAttributePermissionsReadEncryptionRequired = 0x04,
   CBAttributePermissionsWriteEncryptionRequired = 0x08,
} CBAttributePermissions;"

https://developer.apple.com/library/ios/documentation/CoreBluetooth/Reference/CBMutableCharacteristic_Class/Reference/CBMutableCharacteristic.html

【讨论】：