iOS蓝牙开发（二）：iOS 蓝牙4.0中心模式 代码实现

上一篇简单介绍了蓝牙的部分基础知识，详细的东西大家可以去github上搜babyBluetooth，里面有一些学习资料

iOS连接外设的流程

建立中心管理者

扫描外设 discoverPeripheral

连接外设 connectPeripheral

扫描外设中的服务和特征 discoverServices discoverCharacteristics

获取外设的services

获取外设service中的characteristics

获取characteristic的值value、descriptor的value

与外设做数据交互 write、read

订阅characteristic的通知notify

断开连接 disconnected

实现步骤

1、导入CoreBluetooth头文件，建立中心管理类，设置代理

#import <CoreBluetooth/CoreBluetooth.h>
@interface ViewController : UIViewController<CBCentralManagerDelegate>
@interface ViewController (){
//系统蓝牙设备管理对象，可以把他理解为主设备，通过他，可以去扫描和链接外设
CBCentralManager *manager;
//用于保存被发现设备
NSMutableArray *peripherals;
}
- (void)viewDidLoad {
[super viewDidLoad];
/*
设置主设备的委托,CBCentralManagerDelegate
必须实现的：
- (void)centralManagerDidUpdateState:(CBCentralManager *)central;//主设备状态改变的委托，在初始化CBCentralManager的适合会打开设备，只有当设备正确打开后才能使用
其他选择实现的委托中比较重要的：
- (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI; //找到外设的委托
- (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral;//连接外设成功的委托
- (void)centralManager:(CBCentralManager *)central didFailToConnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error;//外设连接失败的委托
- (void)centralManager:(CBCentralManager *)central didDisconnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error;//断开外设的委托
*/
//初始化并设置委托和线程队列，最好一个线程的参数可以为nil，默认会就main线程
manager = [[CBCentralManager alloc]initWithDelegate:self queue:dispatch_get_main_queue()];

2、扫描外设（discover），扫描外设的方法我们放在centralManager成功打开的委托中，因为只有设备成功打开，才能开始扫描，否则会报错。

所以当重新连接外设时，都不会成功，因为states还没打开；一般自己写蓝牙，这个地方要处理一下，连接的时候判断一下，还未打开就重连，一直等到PoweredOn

-(void)centralManagerDidUpdateState:(CBCentralManager *)central{
switch (central.state) {
case CBCentralManagerStateUnknown:
NSLog(@">>>CBCentralManagerStateUnknown");
break;
case CBCentralManagerStateResetting:
NSLog(@">>>CBCentralManagerStateResetting");
break;
case CBCentralManagerStateUnsupported:
NSLog(@">>>CBCentralManagerStateUnsupported");
break;
case CBCentralManagerStateUnauthorized:
NSLog(@">>>CBCentralManagerStateUnauthorized");
break;
case CBCentralManagerStatePoweredOff:
NSLog(@">>>CBCentralManagerStatePoweredOff");
break;
case CBCentralManagerStatePoweredOn:
NSLog(@">>>CBCentralManagerStatePoweredOn");
//开始扫描周围的外设
/*
第一个参数nil就是扫描周围所有的外设，扫描到外设后会进入
- (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI;
*/
[manager scanForPeripheralsWithServices:nil options:nil];
break;
default:
break;
}
}

//扫描到设备会进入方法
-(void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI{

NSLog(@"当扫描到设备:%@",peripheral.name);
//接下来可以连接设备

}

3、连接外设

有一点注意，找到的peripheral必须被持有：(比如添加到数组、赋值给另一个被持有的变量)，否则CBCentralManager中也不会保存这个peripheral，那么CBPeripheralDelegate中的方法也不会被调用

//扫描到设备会进入方法
-(void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI{

//接下连接我们的测试设备，如果你没有设备，可以下载一个app叫lightbule的app去模拟一个设备
//这里自己去设置下连接规则，我设置的是P开头的设备
if ([peripheral.name hasPrefix:@"P"]){
/*
一个主设备最多能连7个外设，每个外设最多只能给一个主设备连接,连接成功，失败，断开会进入各自的委托
- (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral;//连接外设成功的委托
- (void)centralManager:(CBCentralManager *)central didFailToConnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error;//外设连接失败的委托
- (void)centralManager:(CBCentralManager *)central didDisconnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error;//断开外设的委托
*/

//找到的设备必须持有它，否则CBCentralManager中也不会保存peripheral，那么CBPeripheralDelegate中的方法也不会被调用！！
[peripherals addObject:peripheral];
//连接设备
[manager connectPeripheral:peripheral options:nil];
}

}

//连接到Peripherals-成功
- (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral
{
NSLog(@">>>连接到名称为（%@）的设备-成功",peripheral.name);
}

//连接到Peripherals-失败
-(void)centralManager:(CBCentralManager *)central didFailToConnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error
{
NSLog(@">>>连接到名称为（%@）的设备-失败,原因:%@",[peripheral name],[error localizedDescription]);
}

//Peripherals断开连接
- (void)centralManager:(CBCentralManager *)central didDisconnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error{
NSLog(@">>>外设连接断开连接 %@: %@\n", [peripheral name], [error localizedDescription]);

}

4、扫描外设中的服务和特征(discover)

设备连接成功后，就可以扫描设备的服务了，同样是通过委托形式，扫描到结果后会进入委托方法。但是这个委托已经不再是主设备的委托（CBCentralManagerDelegate），而是外设的委托（CBPeripheralDelegate）,这个委托包含了主设备与外设交互的许多 回叫方法，包括获取services，获取characteristics，获取characteristics的值，获取characteristics的Descriptor，和Descriptor的值，写数据，读rssi，用通知的方式订阅数据等等。

5、获取外设的services

//连接到Peripherals-成功
- (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral
{
NSLog(@">>>连接到名称为（%@）的设备-成功",peripheral.name);
//设置的peripheral委托CBPeripheralDelegate
//@interface ViewController : UIViewController<CBCentralManagerDelegate,CBPeripheralDelegate>
[peripheral setDelegate:self];
//扫描外设Services，成功后会进入方法：-(void)peripheral:(CBPeripheral *)peripheral didDiscoverServices:(NSError *)error{
[peripheral discoverServices:nil];

}

//扫描到Services
-(void)peripheral:(CBPeripheral *)peripheral didDiscoverServices:(NSError *)error{
//  NSLog(@">>>扫描到服务：%@",peripheral.services);
if (error)
{
NSLog(@">>>Discovered services for %@ with error: %@", peripheral.name, [error localizedDescription]);
return;
}

for (CBService *service in peripheral.services) {
NSLog(@"%@",service.UUID);
//扫描每个service的Characteristics，扫描到后会进入方法： -(void)peripheral:(CBPeripheral *)peripheral didDiscoverCharacteristicsForService:(CBService *)service error:(NSError *)error
[peripheral discoverCharacteristics:nil forService:service];
}
}

6、获取外设的Characteristics,获取Characteristics的值，获取Characteristics的Descriptor和Descriptor的值

//扫描到Characteristics
-(void)peripheral:(CBPeripheral *)peripheral didDiscoverCharacteristicsForService:(CBService *)service error:(NSError *)error{
if (error)
{
NSLog(@"error Discovered characteristics for %@ with error: %@", service.UUID, [error localizedDescription]);
return;
}

for (CBCharacteristic *characteristic in service.characteristics)
{
NSLog(@"service:%@ 的 Characteristic: %@",service.UUID,characteristic.UUID);
}

//获取Characteristic的值，读到数据会进入方法：-(void)peripheral:(CBPeripheral *)peripheral didUpdateValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error
for (CBCharacteristic *characteristic in service.characteristics){
{
[peripheral readValueForCharacteristic:characteristic];
}
}

//搜索Characteristic的Descriptors，读到数据会进入方法：-(void)peripheral:(CBPeripheral *)peripheral didDiscoverDescriptorsForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error
for (CBCharacteristic *characteristic in service.characteristics){
[peripheral discoverDescriptorsForCharacteristic:characteristic];
}

}

//获取的charateristic的值
-(void)peripheral:(CBPeripheral *)peripheral didUpdateValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error{
//打印出characteristic的UUID和值
//!注意，value的类型是NSData，具体开发时，会根据外设协议制定的方式去解析数据
NSLog(@"characteristic uuid:%@  value:%@",characteristic.UUID,characteristic.value);

}

//搜索到Characteristic的Descriptors
-(void)peripheral:(CBPeripheral *)peripheral didDiscoverDescriptorsForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error{

//打印出Characteristic和他的Descriptors
NSLog(@"characteristic uuid:%@",characteristic.UUID);
for (CBDescriptor *d in characteristic.descriptors) {
NSLog(@"Descriptor uuid:%@",d.UUID);
}

}
//获取到Descriptors的值
-(void)peripheral:(CBPeripheral *)peripheral didUpdateValueForDescriptor:(CBDescriptor *)descriptor error:(NSError *)error{
//打印出DescriptorsUUID 和value
//这个descriptor都是对于characteristic的描述，一般都是字符串，所以这里我们转换成字符串去解析
NSLog(@"characteristic uuid:%@  value:%@",[NSString stringWithFormat:@"%@",descriptor.UUID],descriptor.value);
}

7、把数据写到Characteristic中

//写数据
-(void)writeCharacteristic:(CBPeripheral *)peripheral
characteristic:(CBCharacteristic *)characteristic
value:(NSData *)value{

//打印出 characteristic 的权限，可以看到有很多种，这是一个NS_OPTIONS，就是可以同时用于好几个值，常见的有read，write，notify，indicate，知知道这几个基本就够用了，前连个是读写权限，后两个都是通知，两种不同的通知方式。
/*
typedef NS_OPTIONS(NSUInteger, CBCharacteristicProperties) {
CBCharacteristicPropertyBroadcast                                              = 0x01,
CBCharacteristicPropertyRead                                                   = 0x02,
CBCharacteristicPropertyWriteWithoutResponse                                   = 0x04,
CBCharacteristicPropertyWrite                                                  = 0x08,
CBCharacteristicPropertyNotify                                                 = 0x10,
CBCharacteristicPropertyIndicate                                               = 0x20,
CBCharacteristicPropertyAuthenticatedSignedWrites                              = 0x40,
CBCharacteristicPropertyExtendedProperties                                     = 0x80,
CBCharacteristicPropertyNotifyEncryptionRequired NS_ENUM_AVAILABLE(NA, 6_0)        = 0x100,
CBCharacteristicPropertyIndicateEncryptionRequired NS_ENUM_AVAILABLE(NA, 6_0)  = 0x200
};

*/
NSLog(@"%lu", (unsigned long)characteristic.properties);

//只有 characteristic.properties 有write的权限才可以写
if(characteristic.properties & CBCharacteristicPropertyWrite){
/*
最好一个type参数可以为CBCharacteristicWriteWithResponse或type:CBCharacteristicWriteWithResponse,区别是是否会有反馈
*/
[peripheral writeValue:value forCharacteristic:characteristic type:CBCharacteristicWriteWithResponse];
}else{
NSLog(@"该字段不可写！");
}

}

8、订阅Characteristic的通知

一般在discoverCharacteristic的代理中，发现了类型是notify的characteristic，直接就可以订阅了

//设置通知
-(void)notifyCharacteristic:(CBPeripheral *)peripheral
characteristic:(CBCharacteristic *)characteristic{
//设置通知，数据通知会进入：didUpdateValueForCharacteristic方法
[peripheral setNotifyValue:YES forCharacteristic:characteristic];

}

//取消通知
-(void)cancelNotifyCharacteristic:(CBPeripheral *)peripheral
characteristic:(CBCharacteristic *)characteristic{

[peripheral setNotifyValue:NO forCharacteristic:characteristic];
}

9、断开连接(disconnect)

//停止扫描并断开连接
-(void)disconnectPeripheral:(CBCentralManager *)centralManager
peripheral:(CBPeripheral *)peripheral{
//停止扫描
[centralManager stopScan];
//断开连接
[centralManager cancelPeripheralConnection:peripheral];
}

iOS中蓝牙模块OTA升级（YModem协议）

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