BLE：使用 CoreBluetooth 在 2 個 ios 設備之間傳輸圖像

Question

我有 2 個 iOS 設備：一個是外圍設備，另一個是中央設備。 我希望數據是圖像。

我嘗試使用字符串值並且它工作正常但是對於圖像我收到此錯誤：

read_user_chunkIDOT:1221: 無效的 PNG 文件：沒有有效的 iEnd 塊

我還可以看到字節不同（ <CBCharacteristic: 0x1c40bde20, UUID = 2A38, properties = 0x2, value = (null), notifying = NO> Optional(526 bytes) ），當我得到它們時它們更大。

這是外圍設備：

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])
    }

這是 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)")
    }

我想知道我哪里錯了。

Answer 1

我已經用這段代碼做到了：

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
        }
    }
}

下面的代碼是客戶端：

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)")
    }
}

非常有用的代碼，可幫助您將數據分成塊並使用字符串傳送最后一個塊以通知中央設備傳輸已完成。