【发布时间】：2017-12-04 20:22:33
【问题描述】：
我有这个代码：
//
// Measurement.swift
// BicycleSpeed
import Foundation
import CoreBluetooth
// CSC Measurement
// https://developer.bluetooth.org/gatt/characteristics/Pages/CharacteristicViewer.aspx?u=org.bluetooth.characteristic.csc_measurement.xml
//
// Flags : 1 byte. Bit 0: Wheel. Bit 1: Crank
// Cumulative Wheel revolutions: 4 bytes uint32
// Last wheel event time: 2 bytes. uint16 (1/1024s)
// Cumulative Crank revolutions: 2 bytes uint16
// Last cranck event time: 2 bytes. uint16 (1/1024s)
struct Measurement : CustomDebugStringConvertible {
let hasWheel:Bool
let hasCrank:Bool
let cumulativeWheel:UInt32
let lastWheelEventTime:TimeInterval
let cumulativeCrank:UInt16
let lastCrankEventTime:TimeInterval
let wheelSize:UInt32
init(data:Data, wheelSize:UInt32) {
self.wheelSize = wheelSize
// Flags
var flags:UInt8=0
(data as NSData).getBytes(&flags, range: NSRange(location: 0, length: 1))
hasWheel = ((flags & BTConstants.WheelFlagMask) > 0)
hasCrank = ((flags & BTConstants.CrankFlagMask) > 0)
var wheel:UInt32=0
var wheelTime:UInt16=0
var crank:UInt16=0
var crankTime:UInt16=0
var currentOffset = 1
var length = 0
if ( hasWheel ) {
length = MemoryLayout<UInt32>.size
(data as NSData).getBytes(&wheel, range: NSRange(location: currentOffset, length: length))
currentOffset += length
length = MemoryLayout<UInt16>.size
(data as NSData).getBytes(&wheelTime, range: NSRange(location: currentOffset, length: length))
currentOffset += length
}
if ( hasCrank ) {
length = MemoryLayout<UInt16>.size
(data as NSData).getBytes(&crank, range: NSRange(location: currentOffset, length: length))
currentOffset += length
length = MemoryLayout<UInt16>.size
(data as NSData).getBytes(&crankTime, range: NSRange(location: currentOffset, length: length))
currentOffset += length
}
cumulativeWheel = CFSwapInt32LittleToHost(wheel)
lastWheelEventTime = TimeInterval( Double(CFSwapInt16LittleToHost(wheelTime))/BTConstants.TimeScale)
cumulativeCrank = CFSwapInt16LittleToHost(crank)
lastCrankEventTime = TimeInterval( Double(CFSwapInt16LittleToHost(crankTime))/BTConstants.TimeScale)
}
func timeIntervalForCurrentSample( _ current:TimeInterval, previous:TimeInterval ) -> TimeInterval {
var timeDiff:TimeInterval = 0
if( current >= previous ) {
timeDiff = current - previous
}
else {
// passed the maximum value
timeDiff = ( TimeInterval((Double( UINT16_MAX) / BTConstants.TimeScale)) - previous) + current
}
return timeDiff
}
func valueDiffForCurrentSample<T:UnsignedInteger>( _ current:T, previous:T , max:T) -> T {
var diff:T = 0
if ( current >= previous ) {
diff = current - previous
}
else {
diff = ( max - previous ) + current
}
return diff
}
func valuesForPreviousMeasurement( _ previousSample:Measurement? ) -> ( cadenceinRPM:Double?, distanceinMeters:Double?, speedInMetersPerSecond:Double?)? {
var distance:Double?, cadence:Double?, speed:Double?
guard let previousSample = previousSample else {
return nil
}
if ( hasWheel && previousSample.hasWheel ) {
let wheelTimeDiff = timeIntervalForCurrentSample(lastWheelEventTime, previous: previousSample.lastWheelEventTime)
let valueDiff = valueDiffForCurrentSample(cumulativeWheel, previous: previousSample.cumulativeWheel, max: UInt32.max)
distance = Double( valueDiff * wheelSize) / 1000.0 // distance in meters
if distance != nil && wheelTimeDiff > 0 {
speed = (wheelTimeDiff == 0 ) ? 0 : distance! / wheelTimeDiff // m/s
}
}
if( hasCrank && previousSample.hasCrank ) {
let crankDiffTime = timeIntervalForCurrentSample(lastCrankEventTime, previous: previousSample.lastCrankEventTime)
let valueDiff = Double(valueDiffForCurrentSample(cumulativeCrank, previous: previousSample.cumulativeCrank, max: UInt16.max))
cadence = (crankDiffTime == 0) ? 0 : Double(60.0 * valueDiff / crankDiffTime) // RPM
}
print( "Cadence: \(String(describing: cadence)) RPM. Distance: \(String(describing: distance)) meters. Speed: \(String(describing: speed)) Km/h" )
return ( cadenceinRPM:cadence, distanceinMeters:distance, speedInMetersPerSecond:speed)
}
var debugDescription:String {
get {
return "Wheel Revs: \(cumulativeWheel). Last wheel event time: \(lastWheelEventTime). Crank Revs: \(cumulativeCrank). Last Crank event time: \(lastCrankEventTime)"
}
}
var myMeasurement = ((Measurement?) -> (cadenceinRPM: Double?, DistanceinMeters: Double?, speedinMetersPerSecond: Double?)).self
struct dataVariables {
static var mySpeed = myMeasurement.speedInMetersPerSecond
static var myCadence : Double?
static var miDistance : Double?
static var myLastWheelEventTime : Double? = Measurement.valuesForPreviousMeasurement(lastWheelEventTime)
static var myLastCrankEventTime : Double? = Measurement.valuesForPreviousMeasurement(lastCrankEventTime)
}
}
}
我正在尝试将返回值 cadenceinRPM、distanceinMeters、speedinMetersPerSecond 分配给 struct dataVariables 中的静态变量
以及 lastWheelEventTime 和 lastCrankEventTime，所以我可以在另一个类中访问它们，但是我遇到了以下错误：
在 var mySpeed 上：实例成员“myMeasurement”不能用于“Measurement”类型
在 var myLastWheelEventTime 和 var myLastCrankEventTime 上：实例成员“valuesForPreviousMeasurement”不能用于“Measurement”类型；你的意思是使用这种类型的值吗？
怎么能比那些返回值的引用呢？
有人可以解释错误吗？我搜索了其他类似的问题，但我还没有找到解决方案
我试图将 var myVariable 更改为
var myMeasurement = Measurement.self
但错误保持不变。
还有其他代码
//
// CadenceSensor.swift
import Foundation
import CoreBluetooth
/*
// Bluetooth "Cycling Speed and Cadence"
https://developer.bluetooth.org/gatt/services/Pages/ServiceViewer.aspx?u=org.bluetooth.service.cycling_speed_and_cadence.xml
Service Cycling Speed and Cadence. Characteristic [2A5B] // Measurement
Service Cycling Speed and Cadence. Characteristic [2A5C] // Supported Features
Service Cycling Speed and Cadence. Characteristic [2A5D] // Sensor location
Service Cycling Speed and Cadence. Characteristic [2A55] // Control Point
*/
public struct BTConstants {
static let CadenceService = "1816"
static let CSCMeasurementUUID = "2a5b"
static let CSCFeatureUUID = "2a5c"
static let SensorLocationUUID = "2a5d"
static let ControlPointUUID = "2a55"
static let WheelFlagMask:UInt8 = 0b01
static let CrankFlagMask:UInt8 = 0b10
static let DefaultWheelSize:UInt32 = UInt32(myVariables.circonferenzaRuota!) // In millimiters. 700x30 (by default my bike's wheels) :)
static let TimeScale = 1024.0
}
protocol CadenceSensorDelegate {
func errorDiscoveringSensorInformation(_ error:NSError)
func sensorReady()
func sensorUpdatedValues( speedInMetersPerSecond speed:Double?, cadenceInRpm cadence:Double?, distanceInMeters distance:Double? )
}
class CadenceSensor: NSObject {
let peripheral:CBPeripheral
var sensorDelegate:CadenceSensorDelegate?
var measurementCharasteristic:CBCharacteristic?
var lastMeasurement:Measurement?
let wheelCircunference:UInt32
init(peripheral:CBPeripheral , wheel:UInt32=BTConstants.DefaultWheelSize) {
self.peripheral = peripheral
wheelCircunference = wheel
}
func start() {
self.peripheral.discoverServices(nil)
self.peripheral.delegate = self
}
func stop() {
if let measurementCharasteristic = measurementCharasteristic {
peripheral.setNotifyValue(false, for: measurementCharasteristic)
}
}
func handleValueData( _ data:Data ) {
let measurement = Measurement(data: data, wheelSize: wheelCircunference)
print("\(measurement)")
let values = measurement.valuesForPreviousMeasurement(lastMeasurement)
lastMeasurement = measurement
sensorDelegate?.sensorUpdatedValues(speedInMetersPerSecond: values?.speedInMetersPerSecond, cadenceInRpm: values?.cadenceinRPM, distanceInMeters: values?.distanceinMeters)
}
}
extension CadenceSensor : CBPeripheralDelegate {
func peripheral(_ peripheral: CBPeripheral, didUpdateNotificationStateFor characteristic: CBCharacteristic, error: Error?) {
guard error == nil else {
sensorDelegate?.errorDiscoveringSensorInformation(NSError(domain: CBErrorDomain, code: 0, userInfo: [NSLocalizedDescriptionKey:NSLocalizedString("Error receiving measurements updates", comment:"")]))
return
}
print("notification status changed for [\(characteristic.uuid)]...")
}
func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?) {
print("Updated [\(characteristic.uuid)]...")
guard error == nil , let data = characteristic.value else {
return
}
handleValueData(data)
}
func peripheral(_ peripheral: CBPeripheral, didDiscoverServices error: Error?) {
guard error == nil else {
sensorDelegate?.errorDiscoveringSensorInformation(error! as NSError)
return
}
// Find the cadence service
guard let cadenceService = peripheral.services?.filter({ (service) -> Bool in
return service.uuid == CBUUID(string: BTConstants.CadenceService)
}).first else {
sensorDelegate?.errorDiscoveringSensorInformation(NSError(domain: CBErrorDomain, code: NSNotFound, userInfo: [NSLocalizedDescriptionKey:NSLocalizedString("Cadence service not found for this peripheral", comment:"")]))
return
}
// Discover the cadence service characteristics
peripheral.discoverCharacteristics(nil, for:cadenceService )
print("Cadence service discovered")
}
func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?) {
guard let characteristics = service.characteristics else {
sensorDelegate?.errorDiscoveringSensorInformation(NSError(domain: CBErrorDomain, code: NSNotFound, userInfo: [NSLocalizedDescriptionKey:NSLocalizedString("No characteristics found for the cadence service", comment:"")]))
return
}
print("Received characteristics");
// Enable notifications for the measurement characteristic
for characteristic in characteristics {
print("Service \(service.uuid). Characteristic [\(characteristic.uuid)]")
if characteristic.uuid == CBUUID(string: BTConstants.CSCMeasurementUUID) {
print("Found measurement characteristic. Subscribing...")
peripheral.setNotifyValue(true, for: characteristic)
measurementCharasteristic = characteristic
}
}
sensorDelegate?.sensorReady()
}
}
还有这个其他代码
//
// MainViewController.swift
// BicycleSpeed
import UIKit
import CoreBluetooth
class MainViewController: UIViewController {
struct Constants {
static let ScanSegue = "ScanSegue"
static let SensorUserDefaultsKey = "lastsensorused"
}
var bluetoothManager:BluetoothManager!
var sensor:CadenceSensor?
weak var scanViewController:ScanViewController?
var infoViewController:InfoTableViewController?
var accumulatedDistance:Double?
lazy var distanceFormatter:LengthFormatter = {
let formatter = LengthFormatter()
formatter.numberFormatter.maximumFractionDigits = 1
return formatter
}()
//@IBOutlet var labelBTStatus:UILabel!
@IBOutlet var scanItem:UIBarButtonItem!
@IBOutlet weak var idLabel: UILabel!
override func viewDidLoad() {
bluetoothManager = BluetoothManager()
bluetoothManager.bluetoothDelegate = self
scanItem.isEnabled = false
}
deinit {
disconnectSensor()
}
@IBAction func unwindSegue( _ segue:UIStoryboardSegue ) {
bluetoothManager.stopScan()
guard let sensor = (segue as? ScanUnwindSegue)?.sensor else {
return
}
print("Need to connect to sensor \(sensor.peripheral.identifier)")
connectToSensor(sensor)
}
func disconnectSensor( ) {
if sensor != nil {
bluetoothManager.disconnectSensor(sensor!)
sensor = nil
}
accumulatedDistance = nil
}
func connectToSensor(_ sensor:CadenceSensor) {
self.sensor = sensor
bluetoothManager.connectToSensor(sensor)
// Save the sensor ID
UserDefaults.standard.set(sensor.peripheral.identifier.uuidString, forKey: Constants.SensorUserDefaultsKey)
UserDefaults.standard.synchronize()
}
// TODO: REconnect. Try this every X seconds
func checkPreviousSensor() {
guard let sensorID = UserDefaults.standard.object(forKey: Constants.SensorUserDefaultsKey) as? String else {
return
}
guard let sensor = bluetoothManager.retrieveSensorWithIdentifier(sensorID) else {
return
}
self.sensor = sensor
connectToSensor(sensor)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let infoVC = segue.destination as? InfoTableViewController {
infoViewController = infoVC
}
if segue.identifier == Constants.ScanSegue {
// Scan segue
bluetoothManager.startScan()
scanViewController = (segue.destination as? UINavigationController)?.viewControllers.first as? ScanViewController
}
}
}
extension MainViewController : CadenceSensorDelegate {
func errorDiscoveringSensorInformation(_ error: NSError) {
print("An error ocurred disconvering the sensor services/characteristics: \(error)")
}
func sensorReady() {
print("Sensor ready to go...")
accumulatedDistance = 0.0
}
func updateSensorInfo() {
let name = sensor?.peripheral.name ?? ""
let uuid = sensor?.peripheral.identifier.uuidString ?? ""
OperationQueue.main.addOperation { () -> Void in
self.infoViewController?.showDeviceName(name , uuid:uuid )
}
}
func sensorUpdatedValues( speedInMetersPerSecond speed:Double?, cadenceInRpm cadence:Double?, distanceInMeters distance:Double? ) {
accumulatedDistance? += distance ?? 0
let distanceText = (accumulatedDistance != nil && accumulatedDistance! >= 1.0) ? distanceFormatter.string(fromMeters: accumulatedDistance!) : "N/A"
let speedText = (speed != nil) ? distanceFormatter.string(fromValue: speed!*3.6, unit: .kilometer) + NSLocalizedString("/h", comment:"(km) Per hour") : "N/A"
let cadenceText = (cadence != nil) ? String(format: "%.2f %@", cadence!, NSLocalizedString("RPM", comment:"Revs per minute") ) : "N/A"
OperationQueue.main.addOperation { () -> Void in
self.infoViewController?.showMeasurementWithSpeed(speedText , cadence: cadenceText, distance: distanceText )
}
}
}
extension MainViewController : BluetoothManagerDelegate {
func stateChanged(_ state: CBCentralManagerState) {
print("State Changed: \(state)")
var enabled = false
var title = ""
switch state {
case .poweredOn:
title = "Bluetooth ON"
enabled = true
// When the bluetooth changes to ON, try to reconnect to the previous sensor
checkPreviousSensor()
case .resetting:
title = "Reseeting"
case .poweredOff:
title = "Bluetooth Off"
case .unauthorized:
title = "Bluetooth not authorized"
case .unknown:
title = "Unknown"
case .unsupported:
title = "Bluetooth not supported"
}
infoViewController?.showBluetoothStatusText( title )
scanItem.isEnabled = enabled
}
func sensorConnection( _ sensor:CadenceSensor, error:NSError?) {
print("")
guard error == nil else {
self.sensor = nil
print("Error connecting to sensor: \(sensor.peripheral.identifier)")
updateSensorInfo()
accumulatedDistance = nil
return
}
self.sensor = sensor
self.sensor?.sensorDelegate = self
print("Sensor connected. \(String(describing: sensor.peripheral.name)). [\(sensor.peripheral.identifier)]")
updateSensorInfo()
sensor.start()
}
func sensorDisconnected( _ sensor:CadenceSensor, error:NSError?) {
print("Sensor disconnected")
self.sensor = nil
}
func sensorDiscovered( _ sensor:CadenceSensor ) {
scanViewController?.addSensor(sensor)
}
}
在 MainViewController.swift 中，有这个 func sensorUpdatedValues 将我想要的三个值转换为字符串并在 InfoTableViewController.swift 中初始化 func showMeasurementWithSpeed 。
我可以只返回函数 sensorUpdateValues 中的三个值，以便能够将它们存储到新变量中吗？
【问题讨论】：
-
有多种方法可以在类之间共享数据，但我不明白为什么要在类型中创建这些静态变量。这不是一个非常 Swifty 的解决方案
-
@Andras M. 这些返回值我希望它们显示在与另一个类 InfoViewController 关联的 ViewController 中的标签中。
标签： ios swift core-bluetooth