iOS 蓝牙开发（二）iOS 连接外设的代码实现
上一篇文章介绍了蓝牙的技术知识，这里我们具体说明一下中心模式的应用场景。主设备（手机去扫描连接外设，发现外设服务和属性，操作服务和属性的应用。一般来说，外设（蓝牙设备，比如智能手环之类的东西），会由硬件工程师开发好，并定义好设备提供的服务，每个服务对于的特征，每个特征的属性（只读，只写，通知等等），本文例子的业务场景，就是用一手机app去读写蓝牙设备。
iOS连接外设的代码实现流程
1. 建立中心角色
2. 扫描外设（discover）
3. 连接外设(connect)
4. 扫描外设中的服务和特征(discover)
? ? - 4.1 获取外设的services
? ? - 4.2 获取外设的Characteristics,获取Characteristics的值，获取Characteristics的Descriptor和Descriptor的值
5. 与外设做数据交互(explore and interact)
6. 订阅Characteristic的通知
7. 断开连接(disconnect)
准备环境
? 1 Xcode
? 2 开发证书和手机（蓝牙程序需要使用使用真机调试，使用模拟器也可以调试，但是方法很蛋疼，我会放在最后说）
? 3 蓝牙外设
实现步骤
1 导入CoreBluetooth头文件，建立主设备管理类，设置主设备委托
????#import?
????@interface?ViewController?:?UIViewController
????@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;
????}
????-?(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。
????????-(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(connect)
????????//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
????????????????????*/
????????????????????//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。
4.1 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
????????????[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];
?????????????????????????}
????????}
4.2 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);
????}
5 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！");
????????}
????}
6 订阅Characteristic的通知
????//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];
????}
7 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];
????}
8 模拟器蓝牙调试，慎用，最好还是用真机去调试。
由于在iPhone 4s之后的iOS才支持BLE，新一代的这些iOS设备又都不便宜，在做测试的时候，用iOS模拟器进行调试，可以节约一些开发成本。怎么在iOS模拟器上调试BLE，
苹果最初给出的说明是，支持BLE的mac机子上可以用模拟器进行调试，并给出了一份技术文档（传送门），恶心的是，后来苹果抽风，又把这份文档移除，
并且把iOS 7.0的模拟器上对BLE的支持也移除掉了（难道是想让大家多买设备测试？Apple sucks.）后面，网上搜了一下，解决办法如下：
1. 买一个CSR蓝牙4.0 USB适配器（某宝上大概30块钱），在机子上插入该物（你懂的）
2. 在Terminal下敲入sudo nvram bluetoothHostControllerSwitchBehavior="never" ， 重启Mac。
3. 用XCode 4.6调试代码，在iOS 6.1的模拟器上跑程序（用XCode 5.0跑iOS 7.0模拟器会抛异常，原因上面详诉过了，Apple sucks，你懂的）
如何降低模拟器的iOS版本呢？
XCode->Preferences->Downloads里面有很多simulators你可以下载
选择个6.1的下载好了
代码下载:
我博客中大部分示例代码都上传到了github，地址是：https://github.com/coolnameismy/demo
本文代码存放目录是BleDemo