iOS蓝牙连接票据打印机标签打印机

最近做了蓝牙打印票据以及标签打印机的功能，在这里做一下总结和分享，希望能对有需要的小伙伴提供帮助

首先废话不多说，直接上代码，先搜索到设备，连接设备然后再慢慢了解原理

1、引入头文件 并遵守协议CBCentralManagerDelegate,CBPeripheralDelegate 然后初始化蓝牙管理类

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

2、初始化蓝牙管理类之后会走如下代理回调，当蓝牙状态为CBCentralManagerStatePoweredOn继续下面的回调发现设备

- (void)centralManagerDidUpdateState:(CBCentralManager *)central
{
    NSString * state = nil;
        switch ([central state])
        {
            case CBCentralManagerStateUnsupported:
                state = @"The platform doesn't support the Bluetooth Low Energy Central/Client role.";
                break;
            case CBCentralManagerStateUnauthorized:
                state = @"The application is not authorized to use the Bluetooth Low Energy role.";
                break;
            case CBCentralManagerStatePoweredOff:
                state = @"蓝牙关闭状态";
                break;
            case CBCentralManagerStatePoweredOn:
                state = @"蓝牙打开状态可用";
                break;
            case CBCentralManagerStateUnknown:
            default:
            ;
        }
        NSLog(@"Central manager state: %@", state); 
}

3、发现设备可以获取到设备的名称以及信号强度等，然后选择你要连接的设备执行[centralManager connectPeripheral:peripheral options:@{CBConnectPeripheralOptionNotifyOnConnectionKey : YES}];开始连接

- (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI{
    if (peripheral)
    {
        NSLog(@"foundDevice. name[%s],RSSI[%d]\n",peripheral.name.UTF8String,peripheral.RSSI.intValue);
 [centralManager connectPeripheral:peripheral options:@{CBConnectPeripheralOptionNotifyOnConnectionKey : YES}];
            //发现设备后即可连接该设备 调用完该方法后会调用代理CBCentralManagerDelegate的- (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral表示连接上了设别
            //如果不能连接会调用 - (void)centralManager:(CBCentralManager *)central didFailToConnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error
}

4、设备连接失败进入如下代理回调

- (void)centralManager:(CBCentralManager *)central didFailToConnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error{
    //此时连接发生错误
    NSLog(@"connected periphheral failed");
    [self alertMessage:@"连接失败！"];
}

5、设备连接成功进入如下代理回调,此时设备已经连接上了 你要做的就是找到该设备上的指定服务 调用完该方法后会调用代理CBPeripheralDelegate（现在开始调用另一个代理的方法了）的

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

- (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral
{
    NSLog(@"has connected");
//发现指定server
    [peripheral discoverServices:@[[CBUUID UUIDWithString:kServiceUUID]]];    
//发现所有server
 [peripheral discoverServices:nil];    
}

6、搜索到服务之后根据我们的需要找到我们需要的特性

- (void)peripheral:(CBPeripheral *)peripheral didDiscoverServices:(NSError *)error
{
    if (error==nil) 
    {
        //在这个方法中我们要查找到我们需要的服务  然后调用discoverCharacteristics方法查找我们需要的特性
        //该discoverCharacteristics方法调用完后会调用代理CBPeripheralDelegate的
        //- (void)peripheral:(CBPeripheral *)peripheral didDiscoverCharacteristicsForService:(CBService *)service error:(NSError *)error
        for (CBService *service in peripheral.services) 
        {
                [peripheral discoverCharacteristics:nil forService:service];
        }
    }
}

7、找到需要的read、write、notify特性，到这一步其实蓝牙才算正式建立连接

- (void)peripheral:(CBPeripheral *)peripheral didDiscoverCharacteristicsForService:(CBService *)service error:(NSError *)error{
    if (error==nil) {
        //在这个方法中我们要找到我们所需的服务的特性 然后调用setNotifyValue方法告知我们要监测这个服务特性的状态变化
        //当setNotifyValue方法调用后调用代理CBPeripheralDelegate的- (void)peripheral:(CBPeripheral *)peripheral didUpdateNotificationStateForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error
        for (CBCharacteristic *characteristic in service.characteristics) 
        {
            //写数据
            if ([characteristic.UUID isEqual:[CBUUID UUIDWithString:kWriteCharacteristicUUID]]) 
            {
                   [peripheral setNotifyValue:YES forCharacteristic:characteristic];
                    activeWriteCharacteristic = characteristic;
            }
            //读数据
            else if ([characteristic.UUID isEqual:[CBUUID UUIDWithString:kReadCharacteristicUUID]]) 
            {
                   [peripheral setNotifyValue:YES forCharacteristic:characteristic];
                    activeReadCharacteristic = characteristic;
            }
            //监听蓝牙设备的广播通知
            else if ([characteristic.UUID isEqual:[CBUUID UUIDWithString:kFlowControlCharacteristicUUID]]) {
                [peripheral setNotifyValue:YES forCharacteristic:characteristic];
                activeFlowControlCharacteristic = characteristic;
            }
        }
    }
}

8、接下来我们可以给打印机发送打印指令打印数据

[activeDevice writeValue:data forCharacteristic:activeWriteCharacteristic type:CBCharacteristicWriteWithResponse];

9、CBCharacteristicWriteWithResponse写数据写入成功失败状态会在以下回调中获取

- (void)peripheral:(CBPeripheral *)peripheral didWriteValueForCharacteristic:(CBCharacteristic *)characteristic error:(nullable NSError *)error;
{
    NSLog(@"Write edata success!");
}

10、打印机打印的结果状态会体现在如下回调中

- (void)peripheral:(CBPeripheral *)peripheral didUpdateValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error
{
    NSLog(@"enter didUpdateValueForCharacteristic!");
    NSData *data = characteristic.value; 
    NSLog(@"secondview:read data=%@!",data);
    NSLog(@"qzf come here data=%@",data);
}

总结

以上就是整个蓝牙搜索设备连接设备，发送指令打印的整个流程，当然打印指令发送前还有一个数据的准备阶段，而且不同的打印机支持不同的指令集，这部分后续文章中会写到，如果有小伙伴使用中有不同看法或者疑议的地方，欢迎留言探讨大家一起学习，谢谢