Corebluetooth 中央管理器回调 didDiscoverPeripheral 两次

问题描述

我像这样扫描我的外围设备:

I scan for my peripheral like this:

NSDictionary *scanOptions = [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:NO]
                                                            forKey:CBCentralManagerScanOptionAllowDuplicatesKey];
        // Scan for peripherals with given UUID
        [cm scanForPeripheralsWithServices:[NSArray arrayWithObject:HeliController.serviceUUID] options:scanOptions]

没问题，我找到了外围设备并且能够连接到它.正如你所看到的，我给它 CBCentralManagerScanOptionAllowDuplicatesKey 和 bool NO 以不允许多个外设，但有时 didDiscoverPeripheral 回调会触发两次.

No problem there, I find the peripheral and are able to connect to it. As you can see I give it CBCentralManagerScanOptionAllowDuplicatesKey with bool NO to not allow for more than one peripheral, but sometimes the didDiscoverPeripheralcallback fires twice.

- (void) centralManager:(CBCentralManager *)central
  didDiscoverPeripheral:(CBPeripheral *)peripheral
  advertisementData:(NSDictionary *)advertisementData
               RSSI:(NSNumber *)RSSI
{
if(!discovered){
    discovered = YES;
    NSLog(@"Discovered");

    [cm stopScan];

    [scanButton setTitle:@"Connect" forState:UIControlStateNormal];
}
else if(discovered){
    discovered = YES
    NSLog(@"Already discovered");
}
}

有时我得到

Discovered
Already discovered

作为我控制台中的输出，大多数情况下只显示 Discovered 消息.

as output in my console, and most of the times only the Discoveredmessage shows.

在我的外设委托中，我首先发现服务，然后调用 [peripheraldiscoverCharacteristics 并且回调总是发生:

In my peripheral delegate I first discover services, which then call [peripheral discoverCharacteristics and the callback always occurs:

- (void) peripheral:(CBPeripheral *)peripheral didDiscoverCharacteristicsForService:(CBService *)service error:(NSError *)error{

NSLog(@"Did discover characteristic for service %@", [service.peripheral UUID]);

for(CBCharacteristic *c in [service characteristics]){
    // We never get here when peripheral is discovered twice
    if([[c UUID] isEqual:myCharacteristicUUID]){

        NSLog(@"Found characteristic");

        self.throttleCharacteristic = c;

    }
}

当 didDiscoverPeripheral 出现两次时，service 在此方法中变为 nil，即使 peripheral 不是 (UUID，名称仍然正确).

When didDiscoverPeripheral occur twice, service becomes nilin this method, even though peripheral is not (UUID, name is still correct).

重启手机或重置网络设置可以暂时解决问题.

Rebooting the phone or resetting the network settings fixes the problem temporarily.

我真的需要解决这个问题！谢谢

I really need to get this fixed! Thank you

推荐答案

设备在做广告时可能会返回额外的数据.这些可能以不同的数据包到达，在不同的时间到达.在这种情况下，首先会在最初看到设备时调用 didDiscoverPeripheral，然后在其他信息可用时再次调用.

Devices may return additional data while advertising. These may arrive in separate packets, arriving at different times. In this case, didDiscoverPeripheral is called first when the device is initially seen, and then again when additional information becomes available for it.

CBCentralManagerScanOptionAllowDuplicatesKey 不同.它告诉 CoreBluetooth 您是否希望在设备再次宣传自己时收到重复的结果.它不会阻止对同一发现序列多次调用 didDiscoverPeripheral；它可以防止重复发现序列.

CBCentralManagerScanOptionAllowDuplicatesKey is different. It tells CoreBluetooth whether you want to receive duplicate results when the device advertises itself again. It doesn't prevent multiple calls to didDiscoverPeripheral for the same discovery sequence; it prevents it for repeated discovery sequences.

来源:http://lists.apple.com/archives/bluetooth-dev/2012/Apr/msg00047.html(蓝牙开发的 Apple 代表).

Source: http://lists.apple.com/archives/bluetooth-dev/2012/Apr/msg00047.html (the Apple rep on bluetooth-dev).

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