Why is the function to update my progress slider called 3 times using addPeriodicTimeObserverForInterval in AVPlayer? - ios

Question

Hello I've been trying to figure out this issue and don't know where to look. I'm using AVPlayer to play videos, and I have a UISlider whose value updates every second based on the progresss of the video using addPeriodicTimeObserverForInterval.
When I press pause, the UISlider thumb stops immediately as expected. However, immediately after I press play to resume the video, the thumb moves slightly before it continues progressing as normal every second.
I can't figure out why it's doing this. I'd like to have the UISlider thumb progress fluently, i.e. if I paused the video at 1.5 seconds in, and I play the video again, it SHOULD wait 0.5 seconds before the thumb moves again.
Here's a snippet of my code:
override func viewDidLoad()
{
super.viewDidLoad()
....
isPlaybackSliderTouched = false
isPauseButtonTouched = false
setUpPlayerControls()
....
}
override func viewDidAppear(animated: Bool)
{
super.viewDidAppear(true)
let timeIntervalOne: CMTime = CMTimeMakeWithSeconds(1.0, 10)
playbackSliderTimer = avPlayer.addPeriodicTimeObserverForInterval(timeIntervalOne,
queue: dispatch_get_main_queue()) { (elapsedTime: CMTime) -> Void in
self.observeTime(elapsedTime)
}
....
playPauseButton.addTarget(self, action: "onClick:", forControlEvents: .TouchUpInside)
}
func observeTime(elapsedTime: CMTime)
{
let duration = CMTimeGetSeconds(avPlayer.currentItem!.duration)
if isfinite(duration) && avPlayer.rate == 1
{
print("ENNNTNTTERRR")
let elapsedTime = CMTimeGetSeconds(elapsedTime)
updatePlaybackSlider(elapsedTime: elapsedTime, duration: duration)
}
}
func updatePlaybackSlider(elapsedTime: Float64, duration: Float64)
{
if isPlaybackSliderTouched == false
{
let sliderValue: Float = Float(elapsedTime / duration)
print("sliderValue = \(sliderValue)")
self.playbackSlider.setValue(sliderValue, animated: true)
self.currentTimeLabel.text = self.convertSecondsToHHMMSS(elapsedTime)
self.endTimeLabel.text = self.convertSecondsToHHMMSS(duration - elapsedTime)
print("currentTimeLabel.text = \(currentTimeLabel.text)")
print("endTimeLabel.text = \(endTimeLabel.text)")
}
}
func convertSecondsToHHMMSS(seconds: Float64) -> String
{
let time: Int = Int( floor(seconds) )
print("time = \(time)")
let hh: Int = time / 3600
let mm: Int = (time / 60) % 60
let ss: Int = time % 60
print("seconds = \(ss)")
if hh > 0
{
return String(format: "%02d:%02d:%02d", hh, mm, ss)
}
else
{
return String(format: "%02d:%02d", mm, ss )
}
}
deinit
{
avPlayer.removeTimeObserver(playbackSliderTimer)
}
func onClick(sender: UIButton)
{
print("onClick")
if sender == playPauseButton
{
print("playPauseButton touched")
let playerIsPlaying:Bool = avPlayer.rate > 0
if (playerIsPlaying)
{
isPauseButtonTouched = true
avPlayer.pause()
sender.selected = true
}
else
{
isPauseButtonTouched = false
avPlayer.play()
sender.selected = false
}
}
}
Here's a sample output immediately after I press pause from play state:
setUpPlayerControls
viewDidAppear
ENNNTNTTERRR
sliderValue = 0.0
time = 0
seconds = 0
time = 39
seconds = 39
currentTimeLabel.text = Optional("00:00")
endTimeLabel.text = Optional("-00:39")
ENNNTNTTERRR
sliderValue = 4.76564e-05
time = 0
seconds = 0
time = 39
seconds = 39
currentTimeLabel.text = Optional("00:00")
endTimeLabel.text = Optional("-00:39")
ENNNTNTTERRR
sliderValue = 0.0252767
time = 1
seconds = 1
time = 38
seconds = 38
currentTimeLabel.text = Optional("00:01")
endTimeLabel.text = Optional("-00:38")
ENNNTNTTERRR
sliderValue = 0.0505207
time = 2
seconds = 2
time = 37
seconds = 37
currentTimeLabel.text = Optional("00:02")
endTimeLabel.text = Optional("-00:37")
handleSingleTap
onClick
playPauseButton touched
pause touched
Here's the continuing output when I tap the play from pause state:
onClick
playPauseButton touched
play touched
ENNNTNTTERRR
sliderValue = 0.0718539
time = 2
seconds = 2
time = 36
seconds = 36
currentTimeLabel.text = Optional("00:02")
endTimeLabel.text = Optional("-00:36")
ENNNTNTTERRR
sliderValue = 0.0722224
time = 2
seconds = 2
time = 36
seconds = 36
currentTimeLabel.text = Optional("00:02")
endTimeLabel.text = Optional("-00:36")
ENNNTNTTERRR
sliderValue = 0.0757659
time = 3
seconds = 3
time = 36
seconds = 36
currentTimeLabel.text = Optional("00:03")
endTimeLabel.text = Optional("-00:36")
ENNNTNTTERRR
sliderValue = 0.101012
time = 4
seconds = 4
time = 35
seconds = 35
currentTimeLabel.text = Optional("00:04")
endTimeLabel.text = Optional("-00:35")
As you can see the end of the first output when I press pause to the beginning of the second output when I press play, there is 2 unnecessary calls for time 00:02 to observeTime(elapsedTime), which in turns call my updatePlaybackSlider, which in turn slightly shifts the slider value to the right a bit before it goes back to calling observeTime(elapsedTime) like normal, i.e. every 1 second.
What are some suggestions for me to fix this?
Thanks.