ios藍牙開發（二）ios連接外設的代碼實現

ios連接外設的代碼實現流程

1. 建立中心角色
2. 掃描外設（discover）
3. 連接外設(connect)
4. 掃描外設中的服務和特征(discover)
    - 4.1 獲取外設的services
    - 4.2 獲取外設的Characteristics,獲取Characteristics的值，獲取Characteristics的Descriptor和Descriptor的值
5. 與外設做數據交互(explore and interact)
6. 訂閱Characteristic的通知
7. 斷開連接(disconnect)

准備環境

  1 xcode
  2 開發證書和手機（藍牙程序需要使用使用真機調試，使用模擬器也可以調試，但是方法很蛋疼，我會放在最后說）
  3 藍牙外設

實現步驟

1 導入CoreBluetooth頭文件，建立主設備管理類，設置主設備委托

---

    #import <CoreBluetooth/CoreBluetooth.h>
    @interface ViewController : UIViewController<CBCentralManagerDelegate>


    @interface ViewController (){
        //系統藍牙設備管理對象，可以把他理解為主設備，通過他，可以去掃描和鏈接外設
        CBCentralManager *manager;
        //用於保存被發現設備
        NSMutableArray *peripherals;
    }

    - (void)viewDidLoad {
        [super viewDidLoad];
        /*
         設置主設備的委托,CBCentralManagerDelegate
            必須實現的：
            - (void)centralManagerDidUpdateState:(CBCentralManager *)central;//主設備狀態改變的委托，在初始化CBCentralManager的適合會打開設備，只有當設備正確打開后才能使用
            其他選擇實現的委托中比較重要的：
            - (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI; //找到外設的委托
            - (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral;//連接外設成功的委托
            - (void)centralManager:(CBCentralManager *)central didFailToConnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error;//外設連接失敗的委托
            - (void)centralManager:(CBCentralManager *)central didDisconnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error;//斷開外設的委托
        */
         //初始化並設置委托和線程隊列，最好一個線程的參數可以為nil，默認會就main線程
         manager = [[CBCentralManager alloc]initWithDelegate:self queue:dispatch_get_main_queue()];

2 掃描外設（discover），掃描外設的方法我們放在centralManager成功打開的委托中，因為只有設備成功打開，才能開始掃描，否則會報錯。

---

        -(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");
                    //開始掃描周圍的外設
                    /*
                     第一個參數nil就是掃描周圍所有的外設，掃描到外設后會進入
                          - (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI;
                     */
                    [manager scanForPeripheralsWithServices:nil options:nil];

                    break;
                default:
                    break;
            }

        }

        //掃描到設備會進入方法
        -(void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI{

            NSLog(@"當掃描到設備:%@",peripheral.name);
            //接下來可以連接設備

        }

3 連接外設(connect)

---

        //掃描到設備會進入方法
        -(void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI{

            //接下連接我們的測試設備，如果你沒有設備，可以下載一個app叫lightbule的app去模擬一個設備
            //這里自己去設置下連接規則，我設置的是P開頭的設備
                   if ([peripheral.name hasPrefix:@"P"]){
                   /*
                       一個主設備最多能連7個外設，每個外設最多只能給一個主設備連接,連接成功，失敗，斷開會進入各自的委托
                    - (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral;//連接外設成功的委托
                    - (void)centralManager:(CBCentralManager *)central didFailToConnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error;//外設連接失敗的委托
                    - (void)centralManager:(CBCentralManager *)central didDisconnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error;//斷開外設的委托
                    */

                    //找到的設備必須持有它，否則CBCentralManager中也不會保存peripheral，那么CBPeripheralDelegate中的方法也不會被調用！！
                    [peripherals addObject:peripheral];
                    //連接設備
                   [manager connectPeripheral:peripheral options:nil];
               }

        }


        //連接到Peripherals-成功
        - (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral
        {
            NSLog(@">>>連接到名稱為（%@）的設備-成功",peripheral.name);
        }

        //連接到Peripherals-失敗
        -(void)centralManager:(CBCentralManager *)central didFailToConnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error
        {
            NSLog(@">>>連接到名稱為（%@）的設備-失敗,原因:%@",[peripheral name],[error localizedDescription]);
        }

        //Peripherals斷開連接
        - (void)centralManager:(CBCentralManager *)central didDisconnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error{
            NSLog(@">>>外設連接斷開連接 %@: %@\n", [peripheral name], [error localizedDescription]);

        }

有一點非常容易出錯，大家請注意。在 didDiscoverPeripheral這個委托中有這一行

   //找到的設備必須持有它，否則CBCentralManager中也不會保存peripheral，那么CBPeripheralDelegate中的方法也不會被調用！！ [peripherals addObject:peripheral]; 

請特別注意，如果不保存，會影響到后面的方法執行，這個地方很多人出錯，在我的藍牙交流群中每天幾乎都會因為這個問題導致無法連接和對外設后續的操作。

大家也可以看一下這個委托在xcode中的說明,重點看@discussion中的內容，里面特別指出了需要retained對象。

/*! * @method centralManager:didDiscoverPeripheral:advertisementData:RSSI: * * @param central The central manager providing this update. * @param peripheral A <code>CBPeripheral</code> object. * @param advertisementData A dictionary containing any advertisement and scan response data. * @param RSSI The current RSSI of <i>peripheral</i>, in dBm. A value of <code>127</code> is reserved and indicates the RSSI * was not available. * * @discussion This method is invoked while scanning, upon the discovery of <i>peripheral</i> by <i>central</i>. A discovered peripheral must * be retained in order to use it; otherwise, it is assumed to not be of interest and will be cleaned up by the central manager. For * a list of <i>advertisementData</i> keys, see {@link CBAdvertisementDataLocalNameKey} and other similar constants. * * @seealso CBAdvertisementData.h * */ - (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary<NSString *, id> *)advertisementData RSSI:(NSNumber *)RSSI; 

4掃描外設中的服務和特征(discover)

---

設備連接成功后，就可以掃描設備的服務了，同樣是通過委托形式，掃描到結果后會進入委托方法。但是這個委托已經不再是主設備的委托（CBCentralManagerDelegate），而是外設的委托（CBPeripheralDelegate）,這個委托包含了主設備與外設交互的許多 回叫方法，包括獲取services，獲取characteristics，獲取characteristics的值，獲取characteristics的Descriptor，和Descriptor的值，寫數據，讀rssi，用通知的方式訂閱數據等等。

4.1獲取外設的services

        //連接到Peripherals-成功
        - (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral
        {
            NSLog(@">>>連接到名稱為（%@）的設備-成功",peripheral.name);
            //設置的peripheral委托CBPeripheralDelegate
            //@interface ViewController : UIViewController<CBCentralManagerDelegate,CBPeripheralDelegate>
            [peripheral setDelegate:self];
            //掃描外設Services，成功后會進入方法：-(void)peripheral:(CBPeripheral *)peripheral didDiscoverServices:(NSError *)error{
            [peripheral discoverServices:nil];

        }

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

            for (CBService *service in peripheral.services) {
                             NSLog(@"%@",service.UUID);
                             //掃描每個service的Characteristics，掃描到后會進入方法： -(void)peripheral:(CBPeripheral *)peripheral didDiscoverCharacteristicsForService:(CBService *)service error:(NSError *)error
                             [peripheral discoverCharacteristics:nil forService:service];
                         }

        }

### 4.2獲取外設的Characteristics,獲取Characteristics的值，獲取Characteristics的Descriptor和Descriptor的值

     //掃描到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);
         }

         //獲取Characteristic的值，讀到數據會進入方法：-(void)peripheral:(CBPeripheral *)peripheral didUpdateValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error
         for (CBCharacteristic *characteristic in service.characteristics){
             {
                 [peripheral readValueForCharacteristic:characteristic];
             }
         }

         //搜索Characteristic的Descriptors，讀到數據會進入方法：-(void)peripheral:(CBPeripheral *)peripheral didDiscoverDescriptorsForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error
         for (CBCharacteristic *characteristic in service.characteristics){
             [peripheral discoverDescriptorsForCharacteristic:characteristic];
         }


     }

    //獲取的charateristic的值
    -(void)peripheral:(CBPeripheral *)peripheral didUpdateValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error{
        //打印出characteristic的UUID和值
        //!注意，value的類型是NSData，具體開發時，會根據外設協議制定的方式去解析數據
        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);
        }

    }
    //獲取到Descriptors的值
    -(void)peripheral:(CBPeripheral *)peripheral didUpdateValueForDescriptor:(CBDescriptor *)descriptor error:(NSError *)error{
        //打印出DescriptorsUUID 和value
        //這個descriptor都是對於characteristic的描述，一般都是字符串，所以這里我們轉換成字符串去解析
        NSLog(@"characteristic uuid:%@  value:%@",[NSString stringWithFormat:@"%@",descriptor.UUID],descriptor.value);
    }

5 把數據寫到Characteristic中

---

    //寫數據
    -(void)writeCharacteristic:(CBPeripheral *)peripheral
                characteristic:(CBCharacteristic *)characteristic
                         value:(NSData *)value{

        //打印出 characteristic 的權限，可以看到有很多種，這是一個NS_OPTIONS，就是可以同時用於好幾個值，常見的有read，write，notify，indicate，知知道這幾個基本就夠用了，前連個是讀寫權限，后兩個都是通知，兩種不同的通知方式。
        /*
         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的權限才可以寫
        if(characteristic.properties & CBCharacteristicPropertyWrite){
            /*
                最好一個type參數可以為CBCharacteristicWriteWithResponse或type:CBCharacteristicWriteWithResponse,區別是是否會有反饋
            */
            [peripheral writeValue:value forCharacteristic:characteristic type:CBCharacteristicWriteWithResponse];
        }else{
            NSLog(@"該字段不可寫！");
        }


    }

6 訂閱Characteristic的通知

---

    //設置通知
    -(void)notifyCharacteristic:(CBPeripheral *)peripheral
                characteristic:(CBCharacteristic *)characteristic{
        //設置通知，數據通知會進入：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 斷開連接(disconnect)

---

    //停止掃描並斷開連接
    -(void)disconnectPeripheral:(CBCentralManager *)centralManager
                     peripheral:(CBPeripheral *)peripheral{
        //停止掃描
        [centralManager stopScan];
        //斷開連接
        [centralManager cancelPeripheralConnection:peripheral];
    }

8 模擬器藍牙調試，慎用，最好還是用真機去調試。

---

    由於在iPhone 4s之后的iOS才支持BLE，新一代的這些iOS設備又都不便宜，在做測試的時候，用iOS模擬器進行調試，可以節約一些開發成本。怎么在iOS模擬器上調試BLE，
    蘋果最初給出的說明是，支持BLE的mac機子上可以用模擬器進行調試，並給出了一份技術文檔（傳送門），惡心的是，后來蘋果抽風，又把這份文檔移除，
    並且把iOS 7.0的模擬器上對BLE的支持也移除掉了（難道是想讓大家多買設備測試？Apple sucks.）后面，網上搜了一下，解決辦法如下：
    1. 買一個CSR藍牙4.0 USB適配器（某寶上大概30塊錢），在機子上插入該物（你懂的）
    2. 在Terminal下敲入sudo nvram bluetoothHostControllerSwitchBehavior="never" ， 重啟Mac。
    3. 用XCode 4.6調試代碼，在iOS 6.1的模擬器上跑程序（用XCode 5.0跑iOS 7.0模擬器會拋異常，原因上面詳訴過了，Apple sucks，你懂的）

    如何降低模擬器的IOS版本呢？
    XCode->Preferences->Downloads里面有很多simulators你可以下載
    選擇個6.1的下載好了

---