我正在尝试从蓝牙设备（BR-LE4.0-S2）读取数据。我能够连接BLE设备，但无法从中读取数据。我没有关于BLE服务及其特性的任何规范。在这里我的问题是- (void)peripheral:didUpdateValueForCharacteristic:error:没有被调用。我按照教程“https://developer.apple.com/library/ios/documentation/NetworkingInternetWeb/Conceptual/CoreBluetooth_concepts/PerformingCommonCentralRoleTasks/PerformingCommonCentralRoleTasks.html#//apple_ref/doc/uid/TP40013257-CH3-SW2”。以下是我的代码。
我的要求是从BLE设备连续读取数据。任何帮助是极大的赞赏。
- (void)viewDidLoad
{
self.myCentralManager = [[CBCentralManager alloc] initWithDelegate:self queue:nil];
self.peripheral = [[CBPeripheral alloc] init];
self.peripheral.delegate = self;
[super viewDidLoad];
}
- (void) centralManagerDidUpdateState:(CBCentralManager *)central {
switch (central.state) {
case CBCentralManagerStatePoweredOn:
[self.myCentralManager scanForPeripheralsWithServices:nil options:nil];
break;
default:
NSLog(@"Central Manager did change state");
break;
}
}
- (void)centralManager:(CBCentralManager *)central
didDiscoverPeripheral:(CBPeripheral *)peripheral
advertisementData:(NSDictionary *)advertisementData
RSSI:(NSNumber *)RSSI {
NSLog(@"Discovered %@", peripheral.name);
[self.myCentralManager stopScan];
NSLog(@"Scanning stopped");
if (self.peripheral != peripheral) {
self.peripheral = peripheral;
NSLog(@"Connecting to peripheral %@", peripheral);
// Connects to the discovered peripheral
[self.myCentralManager connectPeripheral:peripheral options:nil];
}
}
- (void)centralManager:(CBCentralManager *)central
didConnectPeripheral:(CBPeripheral *)peripheral {
NSLog(@"Peripheral connected");
NSLog(@"Peripheral services : %@",peripheral.services );
[self.peripheral setDelegate:self];
[peripheral discoverServices:nil];
}
- (void)peripheral:(CBPeripheral *)peripheral
didDiscoverServices:(NSError *)error {
if (error) {
NSLog(@"Error discovering service: %@", [error localizedDescription]);
return;
}
for (CBService *service in peripheral.services) {
[peripheral discoverCharacteristics:nil forService:nil];
}
}
- (void)peripheral:(CBPeripheral *)peripheral
didDiscoverCharacteristicsForService:(CBService *)service
error:(NSError *)error {
int i = 0;
for (CBCharacteristic *characteristic in service.characteristics) {
[peripheral setNotifyValue:YES forCharacteristic: characteristic];
}
}
- (void)peripheral:(CBPeripheral *)peripheral
didUpdateValueForCharacteristic:(CBCharacteristic *)characteristic
error:(NSError *)error {
NSData *data = characteristic.value;
NSString *value = [[NSString alloc] initWithData:characteristic.value encoding:NSUTF8StringEncoding];
NSLog(@"Value %@",value);
NSString *stringFromData = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSLog(@"Data ====== %@", stringFromData);
}
- (void)peripheral:(CBPeripheral *)peripheral
didUpdateNotificationStateForCharacteristic:(CBCharacteristic *)characteristic
error:(NSError *)error {
if (error) {
NSLog(@"Error changing notification state: %@",
[error localizedDescription]);
}
NSString *value = [[NSString alloc] initWithData:self.interestingCharacteristic.value encoding:NSUTF8StringEncoding];
NSLog(@"Value %@",value);
NSLog(@"description: %@, descriptors: %@, properties: %d, service :%@, value:%@", characteristic.description, characteristic.descriptors, characteristic.properties, characteristic.service, characteristic.value);
NSData *data = characteristic.value;
if (characteristic.isNotifying) {
NSString *stringFromData = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
[peripheral readValueForCharacteristic:characteristic];
NSLog(@"Data ====== %@", @"ccdc");
} else {
[self.myCentralManager cancelPeripheralConnection:peripheral];
}
}
- (void)centralManager:(CBCentralManager *)central didDisconnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error
{
NSLog(@"Peripheral Disconnected");
self.peripheral = nil;
// We're disconnected, so start scanning again
NSDictionary *scanOptions = [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:NO] forKey:CBCentralManagerScanOptionAllowDuplicatesKey];
[self.myCentralManager scanForPeripheralsWithServices:nil options:scanOptions];
}
要从BLE外围设备读取值，请执行以下步骤
NSDictionary *options = [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES] forKey:CBCentralManagerScanOptionAllowDuplicatesKey];
[self.myCentralManager scanForPeripheralsWithServices:nil options:options];`
-(void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary *)advertisementData RSSI:(NSNumber *)RSSI {
//Connect detected device....
if (!peripheral.isConnected) {
peripheral.delegate = self;
[bluetoothManager_ connectPeripheral:peripheral options:nil];
}
}
- (void)centralManager:(CBCentralManager *)central didConnectPeripheral:(CBPeripheral *)peripheral{
NSLog(@"Peripheral Connected");
// Make sure we get the discovery callbacks
peripheral.delegate = self;
// Search only for services that match our UUID
[peripheral discoverServices:nil];
}
- (void)peripheral:(CBPeripheral *)peripheral didDiscoverServices:(NSError *)error {
if (error) {
NSLog(@"Error discovering services: %@", [error localizedDescription]);
return;
}
// Loop through the newly filled peripheral.services array, just in case there's more than one.
for (CBService *service in peripheral.services) {
[peripheral discoverCharacteristics:nil forService:service];
}
}
- (void)peripheral:(CBPeripheral *)peripheral didDiscoverCharacteristicsForService:(CBService *)service error:(NSError *)error{
// Deal with errors (if any)
if (error) {
NSLog(@"Error discovering characteristics: %@", [error localizedDescription]);
return;
}
// Again, we loop through the array, just in case.
for (CBCharacteristic *characteristic in service.characteristics) {
if ([characteristic.UUID isEqual:[CBUUID UUIDWithString:REQUIRED_CHARA_ID]]) {
// If it is, subscribe to it
[peripheral setNotifyValue:YES forCharacteristic:characteristic];
}
}
}
您将通过以下方法收到BLE设备的任何通知
- (void)peripheral:(CBPeripheral *)peripheral didUpdateNotificationStateForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error{
if (error) {
NSLog(@"Error changing notification state: %@", error.localizedDescription);
}
// Notification has started
if (characteristic.isNotifying) {
NSLog(@"Notification began on %@", characteristic);
}
}
由于没有调用- (void)peripheral:(CBPeripheral *)peripheral didUpdateValueForCharacteristic:(CBCharacteristic *)characteristic error:(NSError *)error {
if (error) {
NSLog(@"Error reading characteristics: %@", [error localizedDescription]);
return;
}
if (characteristic.value != nil) {
//value here.
}
}
而对itZme's answer进行了一些修改的swift版本（你还需要保留对外围设备的强引用以便连接，如下所示）：
扫描可用设备：
didConnectToPeripheral在检测到设备时，将回拨“didDiscoverPeripheral”委托方法。然后与检测到的BLE设备建立连接。但是首先要保留外围设备的强大参考：
centralManager.scanForPeripheralsWithServices(nil, options: nil)
剩下的应该是这样的：
private var peripherals: [CBPeripheral] = []
func centralManager(central: CBCentralManager, didDiscoverPeripheral peripheral: CBPeripheral, advertisementData: [String : AnyObject], RSSI: NSNumber) {
if peripheral.state != .connected {
self.peripherals.append(peripheral)
peripheral.delegate = self
centralManager.connectPeripheral(peripheral , options: nil)
}
}
extension ViewController: CBPeripheralDelegate {
func centralManager(central: CBCentralManager, didFailToConnectPeripheral peripheral: CBPeripheral, error: NSError?) {
if error != nil {
print("Error connecting to peripheral: \(error?.localizedDescription)")
return
}
}
func centralManager(central: CBCentralManager, didConnectPeripheral peripheral: CBPeripheral) {
print("Peripheral connected.")
peripheral.delegate = self
peripheral.discoverServices(nil)
}
func peripheral(peripheral: CBPeripheral, didDiscoverServices error: NSError?) {
if error != nil {
print("Error discovering services \(error?.localizedDescription)")
return
}
for service: CBService in peripheral.services! {
peripheral.discoverCharacteristics(nil, forService: service)
}
}
func peripheral(peripheral: CBPeripheral, didDiscoverCharacteristicsForService service: CBService, error: NSError?) {
if error != nil {
print("Error discovering characteristics \(error?.localizedDescription)")
return
}
for characteristic: CBCharacteristic in service.characteristics! {
if characteristic.UUID == CBUUID(string: YOUR_CHARACTERISTIC_UUID) {
peripheral.readValueForCharacteristic(characteristic)
// for some devices, you can skip readValue() and print the value here
}
}
}
func peripheral(peripheral: CBPeripheral, didUpdateValueForCharacteristic characteristic: CBCharacteristic, error: NSError?) {
if characteristic.UUID == CBUUID(string: YOUR_CHARACTERISTIC_UUID) {
print(characteristic.value)
}
}
}
首先你必须执行read（）函数。如果执行read（）函数，那么“didUpdateValueForCharesteristics”将会运行。你可以在这个函数中读取字符串值。这很简单。