CoreBluetooth:尝试写入设备 [英] CoreBluetooth: Attempt to write to device
问题描述
我已连接&配对的蓝牙LE手镯(服务ID:FF20),具有2个特征:
I have a connected & paired up Bluetooth LE bracelet (Service ID: FF20), which have 2 characteristics:
- 0xFF21:无响应写入
- 0xFF22:通知
现在,我尝试使用以下代码通过CoreBluetooth Framework将数据写入0xFF21:
Now I try to write data via CoreBluetooth Framework to 0xFF21 with the following code:
我在头文件中定义了2个常量:
I defined 2 constants at header file:
#define TRANSFER_SERVICE_UUID @"FF20"
#define TRANSFER_SERVICE_CHARACTERISTIC_UUID @"FF21"
.m
- (void)viewDidLoad {
[super viewDidLoad];
_centralManager = [[CBCentralManager alloc] initWithDelegate:self queue:nil];
}
- (void)centralManagerDidUpdateState:(CBCentralManager *)central {
if (central.state != CBCentralManagerStatePoweredOn) {
return;
}
if (central.state == CBCentralManagerStatePoweredOn) {
NSArray* connectedDevices = [_centralManager retrieveConnectedPeripheralsWithServices:@[[CBUUID UUIDWithString:TRANSFER_SERVICE_UUID]]];
for (CBPeripheral *peripheral in connectedDevices) {
NSLog(@"Device Found. CBPeripheral = %@", peripheral);
peripheral.delegate = self;
if(peripheral.services.count == 0) {
NSLog(@"No service found");
}
for (CBService *service in peripheral.services) {
if(service.characteristics != nil) {
for (CBCharacteristic *characteristic in service.characteristics) {
if ([characteristic.UUID isEqual:[CBUUID UUIDWithString:TRANSFER_CHARACTERISTIC_UUID]]) {
// check notifying ?
NSData *data = [@"Testing" dataUsingEncoding:NSUTF8StringEncoding];
[peripheral writeValue:data forCharacteristic:characteristic type:CBCharacteristicWriteWithResponse];
} else {
NSLog(@"Specific Characteristic Not found");
}
}
} else {
NSLog(@"Characteristic is NULL");
}
}
}
}
}
日志出现:
Device Found. CBPeripheral = <CBPeripheral: 0x1740f5080, identifier = 4EFF694C-017A-536F-9301-2EB2CC316CBE, name = Bracelet-0366, state = disconnected>
No service found
我错过了什么?
推荐答案
您需要与发现的外围设备建立连接,并致电您的 didConnectPeripheral
委托方法,然后才能发出读/写请求。
You need to issue a connect to the discovered peripheral and get a call to your didConnectPeripheral
delegate method before you can issue read/write requests.
达到 poweredOn
状态您应该发出 scanForDevicesWithServices
调用,等待返回给您的委托的调用,然后连接,发现服务和特征,然后可以发出写操作。
When you reach the poweredOn
state you should issue a scanForDevicesWithServices
call, wait for the call back to your delegate, then connect, discover the service and characteristics, then you can issue a write.
-(void) centralManagerDidUpdateState:(CBCentralManager *)central {
switch (central.state) {
case CBCentralManagerStatePoweredOn:
[central scanForPeripheralsWithServices:@[[CBUUID UUIDWithString:TRANSFER_SERVICE_UUID]] options:nil];
break;
}
}
-(void) centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI {
NSLog(@"Discovered peripheral %@ (%@)",peripheral.name,peripheral.identifier.UUIDString);
if (self.connectedPeripheral == nil) {
[central connectPeripheral:peripheral options:nil];
}
}
-(void) centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral {
self.connectedPeripheral=peripheral;
NSLog(@"Connected to %@(%@)",peripheral.name,peripheral.identifier.UUIDString);
peripheral.delegate=self;
[peripheral discoverServices:@[[CBUUID UUIDWithString:TRANSFER_SERVICE_UUID]];
}
-(void) peripheral:(CBPeripheral *)peripheral didDiscoverServices:(NSError *)error {
for (CBService *service in peripheral.services) {
NSLog(@"Discovered service %@",service.description);
[peripheral discoverCharacteristics:nil forService:service];
}
}
-(void) peripheral:(CBPeripheral *)peripheral didDiscoverCharacteristicsForService:(CBService *)service error:(NSError *)error {
for (CBCharacteristic *characteristic in service.characteristics ) {
NSLog(@"Discovered characteristic %@(%@)",characteristic.description,characteristic.UUID.UUIDString);
if ([characteristic.UUID.UUIDString isEqualToString:TRANSFER_SERVICE_CHARACTERISTIC_UUID) {
NSData *data = [@"Testing" dataUsingEncoding:NSUTF8StringEncoding];
[peripheral writeValue:data forCharacteristic:characteristic type:CBCharacteristicWriteWithoutResponse];
}
}
}
请注意,与您以前的问题,该特征仅支持写而无响应,因此您不能使用 CBCharacteristicWriteWithResponse
Note, that from your previous question the characteristic only supports write without response, so you can't use CBCharacteristicWriteWithResponse
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