如何在iOS中找到蓝牙音频设备

Question

好吧,我正在开发一个有趣的项目,我需要为我的iOS应用程序启用蓝牙音频支持.

我遇到的障碍是我甚至无法开始获得连接的蓝牙音频设备列表.即使我的iPhone 5S识别我的耳机(准确地说是一个~3 - 4岁的LG HBM-230)并通过它播放音频进行电话呼叫,但当我查询两者时,BOTH External Accessory和CoreBluetooth都没有给我任何帮助.

我将我自己的代码基于我发现的CoreBluetooth和External Accessory框架的问题和答案.

当我的代码只是试图" scanForPeripheralsWithServices:nil" 设置 - >蓝牙说的任何蓝牙设备可见并连接时,下面的代码只是CBCentralManagerStatePoweredOn在控制台中的" "消息之外不会出现一次命中.

我的代码中的这一行(带有有效的EAAccessoryManager实例)

NSArray * connectedDevices = [self.eAAccessoryManager connectedAccessories];

还带有一个nil数组.

我能做错什么？

顺便说一下,我已将此代码作为GitHub项目提供.

@implementation BluetoothManager

+ (BluetoothManager *)sharedInstance
{
    static dispatch_once_t pred = 0;
    __strong static id _bluetoothMGR = nil;

    dispatch_once(&pred, ^{
        _bluetoothMGR = [[BluetoothManager alloc] init];
    });

    return _bluetoothMGR;
}

- (id)init
{
    self = [super init];
    if(self)
    {
        dispatch_queue_t centralQueue = dispatch_queue_create("com.yo.mycentral", DISPATCH_QUEUE_SERIAL);

        // whether we try this on a queue of "nil" (the main queue) or this separate thread, still not getting results
        self.cbManager = [[CBCentralManager alloc] initWithDelegate:self queue:centralQueue options:nil];
    }
    return self;
}

// this would hit.... if I instantiated this in a storyboard of XIB file
- (void)awakeFromNib
{
    if(!self.cbManager)
        self.cbManager = [[CBCentralManager alloc] initWithDelegate:self queue:nil options:nil];
}

- (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI {

    NSLog(@"hey I found %@",[advertisementData description]);
}

- (void)centralManager:(CBCentralManager *)central didRetrieveConnectedPeripherals:(NSArray *)peripherals
{
    NSLog( @"I retrieved CONNECTED peripherals");
}

-(void)centralManager:(CBCentralManager *)central didRetrievePeripherals:(NSArray *)peripherals{
    NSLog(@"This is it!");
}

- (void)centralManagerDidUpdateState:(CBCentralManager *)central{
    NSString *messtoshow;

    switch (central.state) {
        case CBCentralManagerStateUnknown:
        {
            messtoshow=@"State unknown, update imminent.";
            break;
        }
        case CBCentralManagerStateResetting:
        {
            messtoshow=@"The connection with the system service was momentarily lost, update imminent.";
            break;
        }
        case CBCentralManagerStateUnsupported:
        {
            messtoshow=@"The platform doesn't support Bluetooth Low Energy";
            break;
        }
        case CBCentralManagerStateUnauthorized:
        {
            messtoshow=@"The app is not authorized to use Bluetooth Low Energy";
            break;
        }
        case CBCentralManagerStatePoweredOff:
        {
            messtoshow=@"Bluetooth is currently powered off.";
            break;
        }
        case CBCentralManagerStatePoweredOn:
        {
            messtoshow=@"Bluetooth is currently powered on and available to use.";
            NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithBool:YES], CBCentralManagerScanOptionAllowDuplicatesKey, nil];

            [_cbManager scanForPeripheralsWithServices:nil options:options];

            break;
        }   

    }
    NSLog(@"%@", messtoshow);
}

@end

Answer 1

首先,您需要配置应用程序音频会话以允许支持音频的蓝牙连接.您可以在例如应用程序委托 - (BOOL)应用程序:(UIApplication*)应用程序didFinishLaunchingWithOptions:(NSDictionary*)launchOptions方法中执行此操作.确保链接AVFoundation Framework并导入将使用它的标头.

#import <AVFoundation/AVFoundation.h>// place in .h

[self prepareAudioSession];// called from application didFinishLaunchingWithOptions

- (BOOL)prepareAudioSession {

     // deactivate session
     BOOL success = [[AVAudioSession sharedInstance] setActive:NO error: nil];
     if (!success) {
         NSLog(@"deactivationError");
     }

     // set audio session category AVAudioSessionCategoryPlayAndRecord options AVAudioSessionCategoryOptionAllowBluetooth
     success = [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayAndRecord withOptions:AVAudioSessionCategoryOptionAllowBluetooth error:nil];
     if (!success) {
         NSLog(@"setCategoryError");
     }

     // activate audio session
     success = [[AVAudioSession sharedInstance] setActive:YES error: nil];
     if (!success) {
         NSLog(@"activationError");
     }

return success;

}

每个应用程序都有一个可以配置的音频会话单例.会话类别和模式(在此示例中,我没有设置模式以使其恢复为默认模式)声明您的应用程序意图,了解您希望如何处理音频路由.它遵循胜利的最后一个重要规则.这意味着如果用户插入耳机或在这种情况下是免提外围设备(HFP)的蓝牙设备,则系统将自动将音频路由到耳机或蓝牙设备.用户物理动作用于确定音频路由.但是,如果您希望向用户提供Apple推荐使用MPVolumeView类的可用路由列表.

添加MPVolumeView的示例可以放在UIViewController子类viewDidLoad方法中.

#import <MediaPlayer/MediaPlayer.h> // place in .h
// prefered way using MPVolumeView for user selecting audio routes
self.view.backgroundColor = [UIColor clearColor];
CGRect frameForMPVV = CGRectMake(50.0, 50.0, 100.0, 100.0);
MPVolumeView *routeView = [[MPVolumeView alloc] initWithFrame:frameForMPVV];
[routeView setShowsVolumeSlider:NO];
[routeView setShowsRouteButton:YES];
[self.view addSubview: routeView];

从iOS 7开始,您可以获得所有这样的输入

// portDesc.portType could be for example - BluetoothHFP, MicrophoneBuiltIn, MicrophoneWired
NSArray *availInputs = [[AVAudioSession sharedInstance] availableInputs];
int count = [availInputs count];
for (int k = 0; k < count; k++) {
    AVAudioSessionPortDescription *portDesc = [availInputs objectAtIndex:k];
    NSLog(@"input%i port type %@", k+1, portDesc.portType);
    NSLog(@"input%i port name %@", k+1, portDesc.portName);
}

您感兴趣的portType是"BluetoothHFP".portName属性通常是您要向用户显示的制造商/型号.(我用非LE蓝牙摩托罗拉恐龙检查了这个并且它有效)

由于最后的胜利规则,您需要观察这两个通知(包括iOS 7).一个用于处理中断(例如电话或警报),第二个用于通知路由更改.路线更改通知是与此问题相关的通知.

[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(myInterruptionSelector:)
                                             name:AVAudioSessionInterruptionNotification
                                           object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(myRouteChangeSelector:)
                                             name:AVAudioSessionRouteChangeNotification
                                           object:nil];

对于iOS 6.x,您可以在myRouteChange:选择器中读取AVAudioSession的currentRoute属性以获取新路由,因为这将在连接耳机或蓝牙设备时被调用.

- (void)myRouteChangeSelector:(NSNotification*)notification {
 AVAudioSessionRouteDescription *currentRoute = [[AVAudioSession sharedInstance] currentRoute];
      NSArray *inputsForRoute = currentRoute.inputs;
      NSArray *outputsForRoute = currentRoute.outputs;
      AVAudioSessionPortDescription *outPortDesc = [outputsForRoute objectAtIndex:0];
      NSLog(@"current outport type %@", outPortDesc.portType);
      AVAudioSessionPortDescription *inPortDesc = [inputsForRoute objectAtIndex:0];
      NSLog(@"current inPort type %@", inPortDesc.portType);
}

任何iOS版本<6.0你都需要' 现已弃用的 'AudioSessionServices类.这个类是一个C api而不是通知它允许你添加属性监听器.

我将在这个笔记上完成 - 你总是不知道你想从系统中得到什么.需要观察中断处理通知并进行大量错误检查.我认为这是一个非常好的问题,我希望这能说明你正在努力实现的目标.