iOS从BLE设备读取数据

Question

我正在尝试从BLE设备读取数据但仍然获得权限错误。演示项目可以在这里找到：https://github.com/sergiomtzlosa/CoreBluetooth-Demo（请记住 - 我的代码与此代码有点不同）。

连接和读取值一般没问题，但有一些特性（必不可少）给出权限错误。

控制台日志：更新错误！特征：“未知（<fff4>）”，错误：“不允许阅读”。

因此，当我订阅或读取该特性的数据时，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（<fff4>）” - >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？反正有没有克服这个问题？

Answer 1

外围设备是嵌入式设备还是另一个iOS设备。我已经看到外围设备的特性必须明确配置为具有读取权限。仅仅因为你发现了一个特征并不意味着你可以阅读它。

Answer 2

您必须检查是否具有访问该值的权限，在初始化CBC特性时设置权限

“特征值权限值表示特征值的读取，写入和加密权限。

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