蓝牙扫描的坑

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今天公司有同事要求手机连接一个蓝牙设备, 要求是手机自动连接过去.简单翻了一下Apple的文档还找了几个网页,觉得了然于心了.于是先写出了进行扫描的代码:

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#import "ViewController.h"
#import <CoreBluetooth/CoreBluetooth.h>
@interface ViewController () <CBCentralManagerDelegate> {
    CBCentralManager *bleManager_;
}
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    bleManager_ = [[CBCentralManager alloc] initWithDelegate:self queue:nil];
    [bleManager_ scanForPeripheralsWithServices:nil options:nil];
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    [bleManager_ stopScan];
}

- (void)centralManagerDidUpdateState:(CBCentralManager *)central {
    NSLog( @"%@", 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" );

        break;
    }
    }
}

- (void)centralManager:(CBCentralManager *)central
 didDiscoverPeripheral:(CBPeripheral *)peripheral
     advertisementData:(NSDictionary<NSString *, id> *)advertisementData
                  RSSI:(NSNumber *)RSSI {
    NSLog( @"BLE found  %@", peripheral.name );
}

- (void)centralManager:(CBCentralManager *)central
  didConnectPeripheral:(CBPeripheral *)peripheral {
    NSLog( @"BLE connected  %@", peripheral.name );
}

- (void)centralManager:(CBCentralManager *)central
    didFailToConnectPeripheral:(CBPeripheral *)peripheral
                         error:(nullable NSError *)error {
    NSLog( @"BLE connected  %@ faild %@", peripheral.name, error );
}

@end

真机运行, 发现打印了 CBCentralManagerStatePoweredOn ,但是之后就没有后文了. 发现外设的代理方法没有调用.但是直接通过手机进行扫描,能够发现设备.反复尝试,还是没有得到预期的结果.

后来想到,自己尝试在手机上反复开关蓝牙让列表刷新,注意到蓝牙开关是有一定时间的.结合自己在代码中:

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bleManager_ = [[CBCentralManager alloc] initWithDelegate:self queue:nil];
[bleManager_ scanForPeripheralsWithServices:nil options:nil];

初始化了直接就开始扫描, 可能是由于蓝牙的Manager还没有准备好吧,于是尝试修改这个开始扫描到判定Manager的状态为PowerOn中:

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case CBCentralManagerStatePoweredOn: {
    NSLog( @"%@", @"CBCentralManagerStatePoweredOn" );
    [bleManager_ scanForPeripheralsWithServices:nil options:nil];

    break;
}

再进行打印,发现终于出现了各个外设了.