蓝牙相关

作为一个中心要实现完整的通讯，一般要经过这样几个步骤：

建立中心角色—扫描外设（discover）—连接外设(connect)—扫描外设中的服务和特征(discover)—与外设做数据交互(explore and interact)—断开连接(disconnect)。

1建立中心角色

首先在我自己类的头文件中要包含CoreBluetooth的头文件，并继承两个协议<CBCentralManagerDelegate,CBPeripheralDelegate>，代码如下:

#import <CoreBluetooth/CoreBluetooth.h>
CBCentralManager *manager;
manager = [[CBCentralManager alloc] initWithDelegate:self queue:nil];

2扫描外设（discover）

代码如下:

[manager scanForPeripheralsWithServices:nil options:options];

这个参数应该也是可以指定特定的peripheral的UUID,那么理论上这个central只会discover这个特定的设备，但是我实际测试发现，如果用特定的UUID传参根本找不到任何设备，我用的代码如下:

NSArray *uuidArray = [NSArray arrayWithObjects:[CBUUID UUIDWithString:@"1800"],[CBUUID UUIDWithString:@"180A"],
[CBUUID UUIDWithString:@"1CB2D155-33A0-EC21-6011-CD4B50710777"],[CBUUID UUIDWithString:@"6765D311-DD4C-9C14-74E1-A431BBFD0652"],nil];

[manager scanForPeripheralsWithServices:uuidArray options:options];

 

目前不清楚原因，怀疑和设备本身在的广播包有关。

3连接外设(connect)

当扫描到4.0的设备后，系统会通过回调函数告诉我们设备的信息，然后我们就可以连接相应的设备，代码如下:

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

    if(![_dicoveredPeripherals containsObject:peripheral])
        [_dicoveredPeripherals addObject:peripheral];

    NSLog(@"dicoveredPeripherals:%@", _dicoveredPeripherals);
}

//连接指定的设备
-(BOOL)connect:(CBPeripheral *)peripheral
{
    NSLog(@"connect start");
    _testPeripheral = nil;

    [manager connectPeripheral:peripheral
                       options:[NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES] forKey:CBConnectPeripheralOptionNotifyOnDisconnectionKey]];

    //开一个定时器监控连接超时的情况
    connectTimer = [NSTimer scheduledTimerWithTimeInterval:5.0f target:self selector:@selector(connectTimeout:) userInfo:peripheral repeats:NO];

    return (YES);
}

4扫描外设中的服务和特征(discover)

同样的，当连接成功后，系统会通过回调函数告诉我们，然后我们就在这个回调里去扫描设备下所有的服务和特征，代码如下:

- (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral
{
    [connectTimer invalidate];//停止时钟

    NSLog(@"Did connect to peripheral: %@", peripheral);
    _testPeripheral = peripheral;

    [peripheral setDelegate:self];
    [peripheral discoverServices:nil];


}

一个设备里的服务和特征往往比较多，大部分情况下我们只是关心其中几个，所以一般会在发现服务和特征的回调里去匹配我们关心那些，比如下面的代码:

- (void)peripheral:(CBPeripheral *)peripheral didDiscoverServices:(NSError *)error
{


    NSLog(@"didDiscoverServices");

    if (error)
    {
        NSLog(@"Discovered services for %@ with error: %@", peripheral.name, [error localizedDescription]);

        if ([self.delegate respondsToSelector:@selector(DidNotifyFailConnectService:withPeripheral:error:)])
            [self.delegate DidNotifyFailConnectService:nil withPeripheral:nil error:nil];

        return;
    }


    for (CBService *service in peripheral.services)
    {

        if ([service.UUID isEqual:[CBUUID UUIDWithString:UUIDSTR_ISSC_PROPRIETARY_SERVICE]])
        {
            NSLog(@"Service found with UUID: %@", service.UUID);
            [peripheral discoverCharacteristics:nil forService:service];
            isVPOS3356 = YES;
            break;
        }


    }
}

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

    if (error)
    {
        NSLog(@"Discovered characteristics for %@ with error: %@", service.UUID, [error localizedDescription]);

        if ([self.delegate respondsToSelector:@selector(DidNotifyFailConnectChar:withPeripheral:error:)])
            [self.delegate DidNotifyFailConnectChar:nil withPeripheral:nil error:nil];

        return;
    }


    for (CBCharacteristic *characteristic in service.characteristics)
    {
        if ([characteristic.UUID isEqual:[CBUUID UUIDWithString:UUIDSTR_ISSC_TRANS_TX]])
        {
            NSLog(@"Discovered read characteristics:%@ for service: %@", characteristic.UUID, service.UUID);

            _readCharacteristic = characteristic;//保存读的特征

            if ([self.delegate respondsToSelector:@selector(DidFoundReadChar:)])
                [self.delegate DidFoundReadChar:characteristic];

            break;
        }
    }


    for (CBCharacteristic * characteristic in service.characteristics)
    {


        if ([characteristic.UUID isEqual:[CBUUID UUIDWithString:UUIDSTR_ISSC_TRANS_RX]])
        {

            NSLog(@"Discovered write characteristics:%@ for service: %@", characteristic.UUID, service.UUID);
            _writeCharacteristic = characteristic;//保存写的特征

            if ([self.delegate respondsToSelector:@selector(DidFoundWriteChar:)])
                [self.delegate DidFoundWriteChar:characteristic];

            break;


        }
    }

    if ([self.delegate respondsToSelector:@selector(DidFoundCharacteristic:withPeripheral:error:)])
        [self.delegate DidFoundCharacteristic:nil withPeripheral:nil error:nil];

}

5与外设做数据交互(explore and interact)

发送数据很简单，我们可以封装一个如下的函数:

//写数据
-(void)writeChar:(NSData *)data
{
    [_testPeripheral writeValue:data forCharacteristic:_writeCharacteristic type:CBCharacteristicWriteWithResponse];
}

_testPeripheral和_writeCharacteristic是前面我们保存的设备对象和可以读写的特征。

然后我们可以在外部调用它，比如当然我要触发刷卡时，先组好数据包，然后调用发送函数:

-(void)msrRead
{

    unsigned char command[512] = {0};
    unsigned charchar *pTmp;
    int nSendLen = 0;
    unsigned char ucCrc[3] = {0};

    _commandType = COMMAND_MSR_READ;

    pTmp = command;


    *pTmp = 0x02;//start
    pTmp++;

    *pTmp = 0xc1;//main cmd
    pTmp++;

    *pTmp = 0x07;//sub cmd
    pTmp++;



    nSendLen = 2;

    *pTmp = nSendLen/256;
    pTmp++;
    *pTmp = nSendLen%256;
    pTmp++;

    *pTmp = 0x00;//sub cmd
    pTmp++;

    *pTmp = 0x00;//sub cmd
    pTmp++;


    Crc16CCITT(command+1,pTmp-command-1,ucCrc);
    memcpy(pTmp,ucCrc,2);


    NSData *data = [[NSData alloc] initWithBytes:&command length:9];
    NSLog(@"send data:%@", data);
    [g_BLEInstance.recvData setLength:0];

    [g_BLEInstance writeChar:data];
}

数据的读分为两种，一种是直接读(reading directly),另外一种是订阅(subscribe)。从名字也能基本理解两者的不同。实际使用中具体用一种要看具体的应用场景以及特征本身的属性。前一个好理解，特征本身的属性是指什么呢？特征有个properties字段(characteristic.properties),它是一个整型值,有如下几个定义:

enum {
     CBCharacteristicPropertyBroadcast = 0x01,
     CBCharacteristicPropertyRead = 0x02,
     CBCharacteristicPropertyWriteWithoutResponse = 0x04,
     CBCharacteristicPropertyWrite = 0x08,
     CBCharacteristicPropertyNotify = 0x10,
     CBCharacteristicPropertyIndicate = 0x20,
     CBCharacteristicPropertyAuthenticatedSignedWrites = 0x40,
     CBCharacteristicPropertyExtendedProperties = 0x80,
     };

比如说，你要交互的特征，它的properties的值是0x10,表示你只能用订阅的方式来接收数据。我这里是用订阅的方式，启动订阅的代码如下:

//监听设备
-(void)startSubscribe
{
    [_testPeripheral setNotifyValue:YES forCharacteristic:_readCharacteristic];
}

当设备有数据返回时，同样是通过一个系统回调通知我，如下所示:

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

    if (error)
    {
        NSLog(@"Error updating value for characteristic %@ error: %@", characteristic.UUID, [error localizedDescription]);

        if ([_mainMenuDelegate respondsToSelector:@selector(DidNotifyReadError:)])
            [_mainMenuDelegate DidNotifyReadError:error];

        return;
    }

    [_recvData appendData:characteristic.value];


    if ([_recvData length] >= 5)//已收到长度
    {
        unsigned charchar *buffer = (unsigned charchar *)[_recvData bytes];
        int nLen = buffer[3]*256 + buffer[4];
        if ([_recvData length] == (nLen+3+2+2))
        {
            //接收完毕，通知代理做事
            if ([_mainMenuDelegate respondsToSelector:@selector(DidNotifyReadData)])
                [_mainMenuDelegate DidNotifyReadData];

        }
    }

}

6 断开连接(disconnect)

这个比较简单，只需要一个API就行了,代码如下:

//主动断开设备
-(void)disConnect
{

    if (_testPeripheral != nil)
    {
        NSLog(@"disConnect start");
        [manager cancelPeripheralConnection:_testPeripheral];
    }

}