ios - 核心蓝牙 : unable to discover characteristics for discovered peripheral

Question

我已经编写了一些 CoreBluetooth 代码，我可以发现设备，但我似乎无法发现我发现的外围设备的特征。谁有好的示例代码可供我用来验证我的代码？

这是我写的:

#import "ViewController.h"
@property(nonatomic, strong) CBCentralManager* centralmanager;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.centralmanager = [[CBCentralManager alloc] initWithDelegate:self queue:nil];
}

- (void)centralManagerDidUpdateState:(CBCentralManager *)central
{
    CBCentralManagerState currentState =  central.state;
    NSLog(@"state %i", currentState);

    switch (central.state)
    {
        case CBCentralManagerStatePoweredOn:
        {
            NSDictionary *options = @{
                                      CBCentralManagerScanOptionAllowDuplicatesKey: @YES
                                      };
            [self.centralmanager scanForPeripheralsWithServices:nil options:options];
            NSLog(@"I just started scanning for peripherals");
            break;
        }
    }
}
- (void)centralManager:(CBCentralManager *)central
  didConnectPeripheral:(CBPeripheral *)peripheral{
    NSLog(@"connected!");
}

- (void) centralManager:(CBCentralManager *)central
  didDiscoverPeripheral:(CBPeripheral *)peripheral
      advertisementData:(NSDictionary *)advertisementData
                   RSSI:(NSNumber *)RSSI
{
    [self.centralmanager connectPeripheral:peripheral options:nil];

    if ([[advertisementData description] containsString:@“keyword”]) {


         NSLog(@"peripheral count %lu", (unsigned long)[peripheral.services count]);
         [peripheral.services count];
       for (int i=0; [peripheral.services count]; i++) {
            for (CBService *s in peripheral.services) {
                [peripheral discoverCharacteristics:nil forService:s];
            }
        }
    }
}


- (void)peripheral:(CBPeripheral *)peripheral didDiscoverCharacteristicsForService:(CBService *)service error:(NSError *)error{
    NSLog(@"did discover characteristic for service");
}

- (void)peripheral:(CBPeripheral *)peripheral didDiscoverServices:(NSArray *)serviceUuids{
    NSLog(@"discovered a peripheral's services: %@", serviceUuids);
}

Answer 1

看这里: Sample Code

基本上流程是:

1. 扫描设备
2. 发现设备
3. 连接到设备
4. 向设备请求服务
5. 向服务询问特征
6. 写入、读取或接收特征通知

随后您不必搜索和发现设备，因为可以从缓存中检索并直接连接之前发现的设备。

编辑:--------------------

阅读范例:[aPeripheral readValueForCharacteristic:aChar];

通知示例:[aPeripheral setNotifyValue:YES forCharacteristic:aChar];

这两个调用都会导致 - (void) peripheral:(CBPeripheral *)aPeripheral didUpdateValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error- 当BLE 设备返回一个值。使用通知时，每次设备更新该特征的值时都会自动调用此回调。