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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
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#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;
}
- (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()];</cbcentralmanagerdelegate></corebluetooth>
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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。
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-(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
}
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3 连接外设(connect)
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//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]);
}
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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
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//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];
}
}</cbcentralmanagerdelegate,cbperipheraldelegate>
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4.2 获取外设的Characteristics,获取Characteristics的值，获取Characteristics的Descriptor和Descriptor的值
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//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);
}
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5 把数据写到Characteristic中
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//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！"
);
}
}
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6 订阅Characteristic的通知
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//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];
}
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7 断开连接(disconnect)
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//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];
}
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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