How to play Audio from the custom position of UISlider? - ios

Question

I'm working on a voice memo app that records sound from user and plays them back.
Recording part works good. The recorded file was stored successfully & when a user taps on a saved file it just starts to play the file.
I'm using UISlider to indicate the play progress. Now, I disabled UISlider's userInteractionEnabled property to NO. So, I don't allow the user to interact with UISlider bar.
What do I need is, I want to enable this property to YES, so that one can choose the desired place to play the audio. For this, I added the following line in my slider code.
[mySlider addTarget:self action:#selector(sliderChanged:) forControlEvents:UIControlEventValueChanged];
By adding the above line, I can find the slider position within sliderChanged: method. But, I don't know how to initiate the player from the selected position. Each file has various sizes so their playing time also differs.
Is there any sample code available? Your help is needed.
Thanks

Answer 1

Sharing a solution in Swift.
I was able to get my project working with the slider based on the objective-c implementation zeeran posted, and it even updates the current time continuously now which mine wasnt doing before. I'm so pleased.
So I want to share the swift implementation in case it helps anyone out there.
import UIKit
import AVFoundation
import Foundation
class ActivityViewController: UIViewController, AVAudioPlayerDelegate {
/// The player & sound file object
var audioPlayer = AVAudioPlayer()
var activitySound = NSURL()
var updater : CADisplayLink! = nil // tracks the time into the track
var updater_running : Bool = false // did the updater start?
var playing : Bool = false //indicates if track was started playing
#IBOutlet var playButton: UIButton!
#IBOutlet var timeLabel: UILabel! // shows time and duration
#IBOutlet var audioSlider: UISlider! // slider object
#IBAction func pressedPlayButton(sender: AnyObject) {
if (playing == false) {
updater = CADisplayLink(target: self, selector: Selector("updateProgress"))
updater.frameInterval = 1
updater.addToRunLoop(NSRunLoop.currentRunLoop(), forMode: NSDefaultRunLoopMode)
updater_running = true
audioPlayer.play()
playButton.selected = true // pause image is assigned to "selected"
playing = true
updateProgress()
} else {
updateProgress() // update track time
audioPlayer.pause() // then pause
playButton.selected = false // show play image (unselected button)
playing = false // note track has stopped playing
}
}
// action for when the slider is moved: set as 'valuechanged' for UISlider object
#IBAction func sliderMoved(sender: UISlider) {
// if the track was playing store true, so we can restart playing after changing the track position
var wasPlaying : Bool = false
if playing == true {
audioPlayer.pause()
wasPlaying = true
}
audioPlayer.currentTime = NSTimeInterval(round(audioSlider.value))
updateProgress()
// starts playing track again it it had been playing
if (wasPlaying == true) {
audioPlayer.play()
wasPlaying == false
}
}
// Timer delegate method that updates current time display in minutes
func updateProgress() {
let total = Float(audioPlayer.duration/60)
let current_time = Float(audioPlayer.currentTime/60)
audioSlider.minimumValue = 0.0
audioSlider.maximumValue = Float(audioPlayer.duration)
audioSlider.setValue(Float(audioPlayer.currentTime), animated: true)
timeLabel.text = NSString(format: "%.2f/%.2f", current_time, total) as String
}
//- AVAudioPlayer delegate method - resets things when track finishe playing
func PlayerDidFinishPlaying(player: AVAudioPlayer!, successfully flag: Bool) {
if flag {
playButton.selected = false
playing = false
audioPlayer.currentTime = 0.0
updateProgress()
updater.invalidate()
}
}
override func viewDidLoad() {
super.viewDidLoad()
// configure AVAudioPlayer as audioPlayer object
let file = NSURL(fileURLWithPath: NSBundle.mainBundle().pathForResource("file1", ofType: "mp3")!)!
audioPlayer = audioPlayer(contentsOfURL: file, error: nil)
audioPlayer.delegate = self
audioSlider.continuous = false
}
// method makes sure updater gets stopped when leaving view controller, because otherwise it will run indefinitely in background
override func viewWillDisappear(animated: Bool) {
if playing == true {
audioPlayer.stop()
}
updater.invalidate()
updater_running = false
super.viewWillDisappear(animated)
}
}

Answer 2

before you load sound file refresh slider min and max values
yourSlider.minValue = 0.0;
yourSlider.maxValue = player.duration;
in method sliderChanged:
player.currentTime = yourSlider.value;

Answer 3

The following code sample should get you started. WIth this , the slider can function as a progress indicator and user can scrub it to start playback at specified position.
/* SliderMoved is invoked when slider value is changed- either when user scrubs it or when it is auto updated as audio playback progresses */
-(void)sliderMoved:(id)sender
{
[self.playbackTimer invalidate];
self.playbackTimer = nil;
NSInteger position = (NSInteger)self.slider.value * 60; // Assume the slider scale is in minutes- so convert to sec
if (self.isPlaying)
{
[self.audioPlayer pause];
}
[self.audioPlayer setCurrentTime:position];
if (self.isPlaying)
{
[self startOrResumePlaying];
}
[self updateSlider];
}
/* updateSlider is a helper function for updating slider value */
-(void)updateSlider
{
float total= self.audioPlayer.duration;
float f = (self.audioPlayer.currentTime) ;
self.slider.value = f/60.0;
self.progressLabel.text = [NSString stringWithFormat:#"%.2f",self.slider.value];
}
/* startOrResumePlaying starts audio playback and initializes a timer that auto increments the progress indicator every 3 sec */
-(void)startOrResumePlaying
{
[self.audioPlayer prepareToPlay];
[self.audioPlayer play];
self.isPlaying = YES;
self.playbackTimer=[NSTimer scheduledTimerWithTimeInterval:3.0
target:self
selector:#selector(handleTimer:)
userInfo:nil
repeats:YES];
[[NSRunLoop currentRunLoop] addTimer:self.playbackTimer forMode:NSDefaultRunLoopMode];
}

Answer 4

Mine is working by combining the above answers of rajagp and Igor Bidiniuc so I'm gonna vote them up both.
#import <AVFoundation/AVFoundation.h>
#property (nonatomic, strong) IBOutlet UIButton *playButton;
#property (nonatomic, strong) IBOutlet UISlider *slider;
#property (nonatomic, strong) IBOutlet UILabel *timeLabel;
#property (nonatomic, strong) AVAudioPlayer *audioPlayer;
#property (nonatomic, strong) NSTimer *timer;
- (IBAction)playPause:(id)sender;
- (IBAction)sliderValueChanged:(id)sender;
Here goes the implementation file.
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.
self.slider.continuous = YES;
NSError *error = nil;
[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:&error];
if (error == nil) {
NSLog(#"audio session initialized successfully");
[self PlayAudio:#"fileName"];
} else {
NSLog(#"error initializing audio session: %#", [error description]);
}
}
- (void)PlayAudio:(NSString*)file {
NSError *error = nil;
NSString *soundPath =[[NSBundle mainBundle] pathForResource:file ofType:#"mp3"];
NSURL *fileURL = [NSURL fileURLWithPath:soundPath];
if ([self.audioPlayer isPlaying]) {
[self.audioPlayer pause];
[self.timer invalidate];
}
self.audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:fileURL error:&error];
self.audioPlayer.delegate = self;
if (error == nil) {
NSLog(#"audio player initialized successfully");
[self playPause:nil];
} else {
NSLog(#"error initializing audio player: %#", [error description]);
}
}
- (void)viewWillDisappear:(BOOL)animated {
if ([self.audioPlayer isPlaying]) {
[self.audioPlayer pause];
[self.timer invalidate];
}
[super viewWillDisappear:animated];
}
-(IBAction)playPause:(id)sender
{
if ([self.audioPlayer isPlaying]) {
[self.audioPlayer pause];
self.playButton.imageView.image = [UIImage imageNamed:#"play"];
[self.timer invalidate];
} else {
[self.audioPlayer play];
self.playButton.imageView.image = [UIImage imageNamed:#"pause"];
self.timer = [NSTimer scheduledTimerWithTimeInterval:1.0f target:self selector:#selector(updateProgress) userInfo:nil repeats:YES];
}
}
- (IBAction)sliderValueChanged:(id)sender {
[self.timer invalidate];
self.timer = nil;
float position = self.slider.value;
if (self.audioPlayer.isPlaying)
{
[self playPause:nil];
}
[self.audioPlayer setCurrentTime:position];
if (self.audioPlayer.isPlaying)
{
[self playPause:nil];
}
[self updateProgress];
}
#pragma mark - Timer delegate
-(void)updateProgress
{
NSInteger durationMinutes = [self.audioPlayer duration] / 60;
NSInteger durationSeconds = [self.audioPlayer duration] - durationMinutes * 60;
NSInteger currentTimeMinutes = [self.audioPlayer currentTime] / 60;
NSInteger currentTimeSeconds = [self.audioPlayer currentTime] - currentTimeMinutes * 60;
NSString *progressString = [NSString stringWithFormat:#"%d:%02d / %d:%02d", currentTimeMinutes, currentTimeSeconds, durationMinutes, durationSeconds];
self.timeLabel.text = progressString;
self.slider.minimumValue = 0.0;
self.slider.maximumValue = [self.audioPlayer duration];
[self.slider setValue:[self.audioPlayer currentTime] animated:YES];
}
#pragma mark - AVAudioPlayer delegate methods
-(void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)player successfully:(BOOL)flag
{
if (flag) {
self.playButton.imageView.image = [UIImage imageNamed:#"play"];
[self.timer invalidate];
}
}

Answer 5

AVAudioPlayer has a currentTime property you can set. Please refer to AVAudioPlayer documentation.