ios - 蓝牙 : image transfer between 2 ios devices using CoreBluetooth

Question

我有 2 台 iOS 设备:一台是外围设备，另一台是中央设备。 我希望数据是图像。

我已经尝试过使用字符串值并且它工作正常但是对于图像我得到了这个错误:

read_user_chunkIDOT:1221: invalid PNG file: no valid iEnd chunk

我还可以看到字节不同 ( <CBCharacteristic: 0x1c40bde20, UUID = 2A38, properties = 0x2, value = (null), notifying = NO> Optional(526 bytes) )，当我得到它们时它们更大。

这是外设:

if let img = UIImage(named: "maiden") {
        let data = UIImagePNGRepresentation(img)
        let base64 = data?.base64EncodedData(options: .lineLength64Characters)
        let char = CBMutableCharacteristic(type: CHAR_UUID, properties: [.read], value: base64!, permissions: [.readable])
        let myRoei = CBMutableService(type: RX_UUID, primary: true)
        
        myRoei.characteristics = [char]
        cameraPeripheralManager.add(myRoei)
        cameraPeripheralManager.startAdvertising([CBAdvertisementDataServiceUUIDsKey:[RX_UUID], CBAdvertisementDataLocalNameKey: advertisementData])
    }

这是 Central 里面的 didUpdateValueFor 特性:

print(characteristic.value as Any)
    switch characteristic.uuid {
    case CHAR_UUID:
        let image = UIImage(data: Data(base64Encoded: characteristic.value!, options: .ignoreUnknownCharacters)!)

        self.imageView.image = image
        _ = bodyLocation(from: characteristic)
    case RX_UUID: break
       // onHeartRateReceived(bpm)
    default:
        print("Unhandled Characteristic UUID: \(characteristic.uuid)")
    }

我想知道我哪里错了。

Answer 1

我已经用这段代码做到了:

func sendData() {
    if sendingEOM {
        // send it
        let didSend = cameraPeripheralManager?.updateValue(
            "EOM".data(using: String.Encoding.utf8)!,
            for: char!,
            onSubscribedCentrals: nil
        )
        // Did it send?
        if (didSend == true) {
            // It did, so mark it as sent
            sendingEOM = false
            print("Sent: EOM")
        }
        return
    }
    
    // We're not sending an EOM, so we're sending data
    
    // Is there any left to send?
    guard sendDataIndex! < (dataToSend?.count)! else {
        // No data left.  Do nothing
        return
    }
    
    // There's data left, so send until the callback fails, or we're done.
    var didSend = true
    
    while didSend {
        // Make the next chunk
        
        // Work out how big it should be
        var amountToSend = dataToSend!.count - sendDataIndex!;
        
        // Can't be longer than 20 bytes
        if (amountToSend > NOTIFY_MTU) {
            amountToSend = NOTIFY_MTU;
        }
        
        // Copy out the data we want
        let chunk = dataToSend!.withUnsafeBytes{(body: UnsafePointer<UInt8>) in
            return Data(
                bytes: body + sendDataIndex!,
                count: amountToSend
            )
        }
        
        // Send it
        didSend = cameraPeripheralManager!.updateValue(
            chunk as Data,
            for: char!,
            onSubscribedCentrals: nil
        )
        
        // If it didn't work, drop out and wait for the callback
        if (!didSend) {
            return
        }
        
        let stringFromData = NSString(
            data: chunk as Data,
            encoding: String.Encoding.utf8.rawValue
        )
        
        print("Sent: \(String(describing: stringFromData))")
        
        // It did send, so update our index
        sendDataIndex! += amountToSend;
        
        // Was it the last one?
        if (sendDataIndex! >= dataToSend!.count) {
            
            // It was - send an EOM
            
            // Set this so if the send fails, we'll send it next time
            sendingEOM = true
            
            // Send it
            let eomSent = cameraPeripheralManager!.updateValue(
                "EOM".data(using: String.Encoding.utf8)!,
                for: char!,
                onSubscribedCentrals: nil
            )
            
            if (eomSent) {
                // It sent, we're all done
                sendingEOM = false
                print("Sent: EOM")
            }
            
            return
        }
    }
}

下面的代码是客户端:

func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?) {
    print(characteristic.value as Any)
    switch characteristic.uuid {
    case Constants.CHAR_UUID:
        imageView.image = nil
        print("Char value: \(String(describing: characteristic.value))")
        guard error == nil else {
            print("Error discovering services: \(error!.localizedDescription)")
            return
        }
        
        if  let stringFromData = NSString(data: characteristic.value!, encoding: String.Encoding.utf8.rawValue){
            
            if  (stringFromData.isEqual(to:"EOM")){
                countNumberOfImages += 1
                imageView.image = UIImage(data: data as Data)
               // peripheral.setNotifyValue(false, for: characteristic)
                print("Image number: \(countNumberOfImages)")

                let end = NSDate()   // <<<<<<<<<<   end time
                print("Total data: \(data.length)")
                
                let start = NSDate() // <<<<<<<<<< Start time
                
                data.setData(NSData() as Data)
                //totalData.setData(NSData() as Data)
               // centralManager?.cancelPeripheralConnection(peripheral)
                
            } else {
                // Otherwise, just add the data on to what we already have
                data.append(characteristic.value!)
                totalData.append(characteristic.value!)
                count += 1
               // print("Times: +\(count)")
                // Log it
                print("Received: \(data.length)")
            }
        } else {
            data.append(characteristic.value!)
            totalData.append(characteristic.value!)
            count += 1
          //  print("Times: +\(count)")
            // Log it
            print("Received: \(data.length)")
        }
    default:
        print("Unhandled Characteristic UUID: \(characteristic.uuid)")
    }
}

非常有用的代码，可帮助您将数据分成 block 并使用字符串传送最后一个 block 以通知中央设备传输已完成。