I'm using Core Motion to see if the phone is facing upwards or downwards, and I only need to retrieve the data once. Here is some of my code:
let manager = CMMotionManager()
manager.showsDeviceMovementDisplay = true
// "Pull data" - since I only need it once
manager.deviceMotionUpdateInterval = 1.0 / 60.0
manager.startDeviceMotionUpdates(using: .xMagneticNorthZVertical)
// Repeats set to false since I only need it once - but same problem even when set to true
self.timer = Timer(fire: Date(), interval: 1.0 / 60.0, repeats: false) { _ in
print("Timer started")
if let motionData = manager.deviceMotion?.gravity.z {
print("Successfully unwrapped")
if 0.7...1 ~= motionData { // Facing downwards
print("Facing downwards")
position = .downwards(motionData)
} else if -1...(-0.7) ~= motionData { // Facing upwards
print("Facing upwards")
position = .upwards(motionData)
} else {
print("Position uknown")
position = .unknown
}
}
}
RunLoop.current.add(self.timer!, forMode: RunLoop.Mode.default)
However, I never reach "Successfully unwrapped". From my attempts to debug, I found that manager.isDeviceMotionActive is never set to true, even though I called startDeviceMotionUpdates(using: .xMagneticNorthZVertical). Why could that be?
Where is this declared? is it possible your reference to the manager is deallocating?
try storing it in a property somewhere that won't get destroyed after the function is called maybe
Related
I'm somewhat new to this and this is my first question on stackoverflow. Thanks in advance for your help and bear with me if my formatting sucks
I've got multiple views within my app (all displaying data using tableview subviews) that need to update automatically when the data changes on the database (Firestore), i.e. another user updates the data.
I've found a way to do this which is working well, but I want to ask the community if there's a better way.
Currently, I am creating a Timer object with a timeInterval of 2. On the interval, the timer queries the database and checks a stored data sample against updated data. If the two values vary, I run viewDidLoad which contains my original query, tableView.reloadData(), etc..
Any suggestions or affirmations would be very useful.
var timer = Timer()
var oldChallengesArray = [String]()
var newChallengesArray = [String]()
override func viewDidLoad() {
super.viewDidLoad()
//set tableview delegate
mainTableView.delegate = self
mainTableView.dataSource = self
//set challengesmodel delegate
challengesModel.delegate = self
//get challenges
DispatchQueue.main.async {
self.challengesModel.getChallenges(accepted: true, challengeDenied: false, incomingChallenges: false, matchOver: false)
self.mainTableView.reloadData()
}
scheduledTimerWithTimeInterval()
}
func scheduledTimerWithTimeInterval(){
// Scheduling timer to Call the function "updateCounting" with the interval of 1 seconds
timer = Timer.scheduledTimer(timeInterval: 2, target: self, selector: #selector(self.updateTableView), userInfo: nil, repeats: true)
}
#objc func updateTableView(){
ChallengeService.getAllUserChallengeIDs(accepted: true, challengeDenied: false, matchOver: false) { (array) in
if array.isEmpty {
return
} else {
self.newChallengesArray = array
if self.oldChallengesArray != self.newChallengesArray {
self.oldChallengesArray = self.newChallengesArray
self.newChallengesArray.removeAll()
self.viewDidLoad()
}
}
}
}
Firestore is a "realtime database", that means that the database warns you when changes happen to the data. To achieve that the app needs to subscribe to relevant changes in the db. The sample code below can be found here:
db.collection("cities").document("SF")
.addSnapshotListener { documentSnapshot, error in
guard let document = documentSnapshot else {
print("Error fetching document: \(error!)")
return
}
guard let data = document.data() else {
print("Document data was empty.")
return
}
print("Current data: \(data)")
}
Also, I would like to point out that calling viewDidLoad is incorrect, you should never call viewDidLoad yourself, create an func to update the data. Something like this:
DispatchQueue.main.async {
self.mainTableView.reloadData()
}
I have an app that does a countdown with a Timer. The countdown tracks multiple steps (all at the same intervals) as well as the total time left, and updates 2 separate UILabels accordingly. Occasionally, the labels will be out of sync.
I can't say for sure, but I think it might be only happening when I pause the countdown sometimes, and usually on steps later than the first step. It's most apparent on the last step when the two labels should be displaying the same exact thing, but will sometimes be 1 second off.
The other tricky thing is that sometimes pausing and resuming after the time has gone out of sync will get it back in sync.
My guess is I'm getting something weird happening in the pause code and/or the moving between steps, or maybe the calculating and formatting of TimeIntervals. Also I'm using rounded() on the calculated TimeIntervals because I noticed only updating the timer every 1s the labels would freeze and skip seconds a lot. But I'm unsure if that's the best way to solve this problem.
Here's the relevant code. (still need to work on refactoring but hopefully it's easy to follow, I'm still a beginner)
#IBAction func playPauseTapped(_ sender: Any) {
if timerState == .running {
//pause timer
pauseAnimation()
timer.invalidate()
timerState = .paused
pausedTime = Date()
playPauseButton.setImage(UIImage(systemName: "play.circle"), for: .normal)
} else if timerState == .paused {
//resume paused timer
guard let pause = pausedTime else { return }
let pausedInterval = Date().timeIntervalSince(pause)
startTime = startTime?.addingTimeInterval(pausedInterval)
endTime = endTime?.addingTimeInterval(pausedInterval)
currentStepEndTime = currentStepEndTime?.addingTimeInterval(pausedInterval)
pausedTime = nil
startTimer()
resumeAnimation()
timerState = .running
playPauseButton.setImage(UIImage(systemName: "pause.circle"), for: .normal)
} else {
//first run of brand new timer
startTimer()
startProgressBar()
startTime = Date()
if let totalTime = totalTime {
endTime = startTime?.addingTimeInterval(totalTime)
}
currentStepEndTime = Date().addingTimeInterval(recipeInterval)
timerState = .running
playPauseButton.setImage(UIImage(systemName: "pause.circle"), for: .normal)
currentWater += recipeWater[recipeIndex]
currentWeightLabel.text = "\(currentWater)g"
}
}
func startTimer() {
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(runTimer), userInfo: nil, repeats: true)
}
#objc func runTimer() {
let currentTime = Date()
guard let totalTimeLeft = endTime?.timeIntervalSince(currentTime).rounded() else { return }
guard let currentInterval = currentStepEndTime?.timeIntervalSince(currentTime).rounded() else { return }
//end of current step
if currentInterval <= 0 {
//check if end of recipe
if recipeIndex < recipeWater.count - 1 {
//move to next step
totalTimeLabel.text = totalTimeLeft.stringFromTimeInterval()
currentStepEndTime = Date().addingTimeInterval(recipeInterval)
startProgressBar()
currentStepTimeLabel.text = recipeInterval.stringFromTimeInterval()
stepsTime += recipeInterval
recipeIndex += 1
//update some ui
} else {
//last step
currentStepTimeLabel.text = "00:00"
totalTimeLabel.text = "00:00"
timer.invalidate()
//alert controller saying finished
}
} else {
//update time labels
currentStepTimeLabel.text = currentInterval.stringFromTimeInterval()
totalTimeLabel.text = totalTimeLeft.stringFromTimeInterval()
}
}
extension TimeInterval {
func stringFromTimeInterval() -> String {
let time = NSInteger(self)
let seconds = time % 60
let minutes = (time / 60) % 60
return String(format: "%0.2d:%0.2d",minutes,seconds)
}
}
EDIT UPDATE: I tried a few different things but still kept having the same issue. I started testing with printing the TimeInterval and the formatted string to compare and see what's off. It's definitely some sort of rounding error.
Total - 173.50678288936615 / 02:54
Step - 39.00026595592499 / 00:39
Total - 172.5073879957199 / 02:53
Step - 38.00087106227875 / 00:38
Total - 171.1903439760208 / 02:51
Step - 36.68382704257965 / 00:37
Total - 170.19031596183777 / 02:50
Step - 35.683799028396606 / 00:36
As you can see, the total time skips from 2:53 to 2:51, but the step timer remains consistent. The reason is the TimeInterval for total goes from 172.5 which gets rounded up, to 171.19 which gets rounded down.
I've also watched the timer count down without touching pause, and it remains in sync reliably. So I've narrowed it down to my pause code.
Fixed my issue and posting here for posterity. I ended up making my totalTimeLeft and currentInterval global properties. Then, on pause and resume, instead of tracking the paused time and adding it to endTime, I just used the totalTimeLeft and currentInterval values that are still stored from the last Timer firing and doing endTime = Date().addingTimeInterval(totalTimeLeft) and the same with the interval time. This got rid of the paused time adding weird amounts that would mess up the rounding.
I am working on a Swift playground and I am trying to use this code to get the device motion.
#objc func update()
{
if let deviceMotion = motionManager.deviceMotion {
print("Device Motion Yaw: \(deviceMotion.attitude.yaw)")
}
}
However, it seems that device motion does not work on a Swift playground even though it works in iOS. How would I change a playground to support device motion? I am using an iPad running iOS 12 and the latest version of Swift Playgrounds and a Mac for the code. I know that the method gets called perfectly, and the code runs perfectly when I put it as part of an iOS app on both an iPad and an iPhone. How would I modify a playground to support this, as from my understanding it does not by default?
It is entirely possible. I’ve done it on several occasions. You’ll need a CMMotionManager class. There are many ways to do this, but I would recommend using a timer. Here is some example code, taken from Apple’s developer documentation and modified to fit the question.
let motion = CMMotionManager()
func startDeviceMotion() {
if motion.isDeviceMotionAvailable {
//How often to push updates
self.motion.deviceMotionUpdateInterval = 1.0/60.0
self.motion.showsDeviceMovementDisplay = true
self.motion.startDeviceMotionUpdates(using: .xMagneticNorthZVertical)
// Configure a timer to fetch the motion data.
self.timer = Timer(fire: Date(), interval: (1.0 / 60.0), repeats: true,
block: { (timer) in
if let data = self.motion.deviceMotion {
let x = data.attitude.pitch
let y = data.attitude.roll
let z = data.attitude.yaw
//Use the data
}
})
RunLoop.current.add(self.timer!, forMode: RunLoop.Mode.default)
}
}
startDeviceMotionUpdates()
Either do that or try something like this, also from the documentation
func startQueuedUpdates() {
if motion.isDeviceMotionAvailable { self.motion.deviceMotionUpdateInterval = 1.0 / 60.0
self.motion.showsDeviceMovementDisplay = true
self.motion.startDeviceMotionUpdates(using: .xMagneticNorthZVertical,
to: self.queue, withHandler: { (data, error) in
// Make sure the data is valid before accessing it.
if let validData = data {
// Get the attitude relative to the magnetic north reference frame.
let roll = validData.attitude.roll
let pitch = validData.attitude.pitch
let yaw = validData.attitude.yaw
// Use the motion data in your app.
}
})
}
}
I try to implement simple player with UISlider to indicate at what time is current audio file.
In code I have added two observers:
slider.rx.value.subscribe(onNext: { value in
let totalTime = Float(CMTimeGetSeconds(self.player.currentItem!.duration))
let seconds = value * totalTime
let time = CMTime(seconds: Double(seconds), preferredTimescale: CMTimeScale(NSEC_PER_SEC))
self.player.seek(to: time)
}).disposed(by: bag)
let interval = CMTime(seconds: 0.1, preferredTimescale: CMTimeScale(NSEC_PER_SEC))
player.addPeriodicTimeObserver(forInterval: interval, queue: nil) { [weak self] time in
self?.updateSlider(with: time)
}
with one private function:
private func updateSlider(with time: CMTime) {
let currentTime = CMTimeGetSeconds(time)
var totalTime = CMTimeGetSeconds(player.currentItem!.duration)
if totalTime.isNaN {
totalTime = 0
}
startLabel.text = Int(currentTime).descriptiveDuration
endLabel.text = Int(totalTime).descriptiveDuration
slider.value = Float(currentTime / totalTime)
}
When audio plays, everything is fine and slider is pretty much updated. The problem occurs when I try to move slider manually while audio is playing, then it jumps. Why?
UPDATE:
I know why actually. Because I update it twice: manually and from player observer, but how to prevent from this behaviour? I have no idea;) please, help.
One simple way to go about this would be to prevent addPeriodicTimeObserver from calling self?.updateSlider(with: time) when the slider is being touched.
This can be determined via the UISliders isTracking property:
isTracking
A Boolean value indicating whether the control is currently tracking
touch events.
While tracking of a touch event is in progress, the control sets the
value of this property to true. When tracking ends or is cancelled for
any reason, it sets this property to false.
Ref: https://developer.apple.com/documentation/uikit/uicontrol/1618210-istracking
This is present in all UIControl elements which you can use in this way:
player.addPeriodicTimeObserver(forInterval: interval, queue: nil) { [weak self] time in
//check if slider is being touched/tracked
guard self?.slider.isTracking == false else { return }
//if slider is not being touched, then update the slider from here
self?.updateSlider(with: time)
}
Generic Example:
#IBOutlet var slider: UISlider!
//...
func startSlider() {
slider.value = 0
slider.maximumValue = 10
Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true) { [weak self] (timer) in
print("Slider at: \(self?.slider.value)")
guard self?.slider.isTracking == false else { return }
self?.updateSlider(to: self!.slider.value + 0.1)
}
}
private func updateSlider(to value: Float) {
slider.value = value
}
I'm sure there are other (better) ways out there but I haven't done much in RxSwift (yet).
I hope this is good enough for now.
self.adaResponseApi runs twice when the timer hits 1.5 seconds after the last recorded speech input. It should only run once.
It is specifically running from the 1.5 interval instantiation and not from the first instantiation, which is triggered when the user specifically-stops speech input.
recognitionTask = speechRecognizer.recognitionTask(with: recognitionRequest, resultHandler: { (result, error) in
if result != nil {
self.textView.text = result?.bestTranscription.formattedString
self.isFinal = (result?.isFinal)!
}
if let timer = self.detectionTimer, (timer.isValid) {
if self.isFinal! {
self.detectionTimer?.invalidate()
self.adaResponseApi()
self.isFinal = true
}
} else { // if self.isFinal == false
self.detectionTimer = Timer.scheduledTimer(withTimeInterval: 1.5, repeats: false, block: { timer in
self.adaResponseApi() // This call gets triggered twice and for the life of me I can't figure out why.
timer.invalidate()
self.isFinal = true
})
}
})
OK here goes... I'm assuming that the request has shouldReportPartialResults set to true (default value).
recognitionTask = speechRecognizer.recognitionTask(with: recognitionRequest) { [weak self] (result, error) in
// [weak self] to stop memory leaks
guard let result = result else {
// no result means probably an error, you should report that to your user
return
}
// display the most accurate transcription (partial or final)
self?.textView.text = result.bestTranscription.formattedString
// invalidate timer
// result is final (and so should invalidate timer)
// or result is partial (and so will create new timer ... and invalidate this one)
self?.detectionTimer?.invalidate()
if result.isFinal {
// we have a final result... use it
self?.adaResponseApi()
} else {
// create timer for if the next response times out
self?.detectionTimer = Timer.scheduledTimer(withTimeInterval: 1.5, repeats: false) { [weak self] timer in
self?.adaResponseApi()
}
}
}
I think I would do it something like this...
I'm not 100% certain what your timer is there for so I assumed it's there in case the recogniser does not return a response quickly and so we can fall back to the most recent partial result?
I also don't think we should need to store the value of result.isFinal. If you do need that then you can add it to the line after self?.textView.text = result.bestTranscription.formattedString.