Running the voice recorder while in another view? - iphone

Question

Hello Okay right I have a view called 'RecordViewController' this has the voice recorder function so once the user presses 'record', it records their voice, I have also created a 'back' button. But once that back button is tapped the voice recording also stops. I want it so once the user goes back, its still recording their voice. Here is the code I used:
.h
#import <UIKit/UIKit.h>
#import <AVFoundation/AVFoundation.h>
#import <CoreAudio/CoreAudioTypes.h>
#interface RecordViewController : UIViewController <AVAudioRecorderDelegate> {
IBOutlet UIButton * btnStart;
IBOutlet UIButton * btnPlay;
IBOutlet UIActivityIndicatorView * actSpinner;
BOOL toggle;
NSURL * recordedTmpFile;
AVAudioRecorder * recorder;
NSError * error;
NSTimer *theTimer;
IBOutlet UILabel *seconds;
int mainInt;
NSString *timeRemainingString;
}
#property (nonatomic,retain)IBOutlet UIActivityIndicatorView * actSpinner;
#property (nonatomic,retain)IBOutlet UIButton * btnStart;
#property (nonatomic,retain)IBOutlet UIButton * btnPlay;
- (IBAction) start_button_pressed;
- (IBAction) play_button_pressed;
- (IBAction)goBack:(id)sender;
- (void)countUp;
#end
.m
#import "RecordViewController.h"
#implementation RecordViewController
#synthesize actSpinner, btnStart, btnPlay;
- (void)countUp {
mainInt += 1;
seconds.text = [NSString stringWithFormat:#"%02d", mainInt];
}
- (IBAction)goBack:(id)sender; {
[self dismissModalViewControllerAnimated:YES];
}
- (void)viewDidLoad {
[super viewDidLoad];
//Start the toggle in true mode.
toggle = YES;
btnPlay.hidden = YES;
//Instanciate an instance of the AVAudioSession object.
AVAudioSession * audioSession = [AVAudioSession sharedInstance];
//Setup the audioSession for playback and record.
//We could just use record and then switch it to playback leter, but
//since we are going to do both lets set it up once.
[audioSession setCategory:AVAudioSessionCategoryPlayAndRecord
error: &error];
//Activate the session
[audioSession setActive:YES error: &error];
}
- (IBAction)start_button_pressed {
if(toggle) {
toggle = NO;
[actSpinner startAnimating];
[btnStart setImage:[UIImage imageNamed:#"stoprecording.png"]
forState:UIControlStateNormal];
mainInt = 0;
theTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:#selector(countUp) userInfo:nil repeats:YES];
btnPlay.enabled = toggle;
btnPlay.hidden = !toggle;
//Begin the recording session.
//Error handling removed. Please add to your own code.
//Setup the dictionary object with all the recording settings that this
//Recording sessoin will use
//Its not clear to me which of these are required and which are the bare minimum.
//This is a good resource: http://www.totodotnet.net/tag/avaudiorecorder/
NSMutableDictionary* recordSetting = [[NSMutableDictionary alloc] init];
[recordSetting setValue :[NSNumber numberWithInt:kAudioFormatAppleIMA4] forKey:AVFormatIDKey];
[recordSetting setValue:[NSNumber numberWithFloat:44100.0] forKey:AVSampleRateKey];
[recordSetting setValue:[NSNumber numberWithInt:2] forKey:AVNumberOfChannelsKey];
//Now that we have our settings we are going to instanciate an instance of our recorder instance.
//Generate a temp file for use by the recording.
//This sample was one I found online and seems to be a good choice for making a tmp file that
//will not overwrite an existing one.
NSString *fileName = [NSString stringWithFormat:#"%.0f.caf", [NSDate timeIntervalSinceReferenceDate] * 1000.0];
NSString *path = [NSTemporaryDirectory() stringByAppendingPathComponent:fileName];
recordedTmpFile = [NSURL fileURLWithPath:path];
NSLog(#"Using File called: %#",recordedTmpFile);
//Setup the recorder to use this file and record to it.
recorder = [[AVAudioRecorder alloc] initWithURL:recordedTmpFile settings:recordSetting error:&error];
//Use the recorder to start the recording.
//Im not sure why we set the delegate to self yet.
//Found this in antother example, but Im fuzzy on this still.
[recorder setDelegate:self];
//We call this to start the recording process and initialize
//the subsstems so that when we actually say "record" it starts right away.
[recorder prepareToRecord];
//Start the actual Recording
[recorder record];
//There is an optional method for doing the recording for a limited time see
//[recorder recordForDuration:(NSTimeInterval) 10]
} else {
toggle = YES;
[actSpinner stopAnimating];
[btnStart setImage:[UIImage imageNamed:#"recordrecord.png"] forState:UIControlStateNormal];
btnPlay.enabled = toggle;
btnPlay.hidden = !toggle;
[theTimer invalidate];
NSLog(#"Using File called: %#",recordedTmpFile);
//Stop the recorder.
[recorder stop];
}
}
- (IBAction)play_button_pressed{
//The play button was pressed...
//Setup the AVAudioPlayer to play the file that we just recorded.
AVAudioPlayer * avPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:recordedTmpFile error:&error];
[avPlayer prepareToPlay];
[avPlayer play];
}
- (void)viewDidUnload {
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
//Clean up the temp file.
NSFileManager * fm = [NSFileManager defaultManager];
[fm removeItemAtPath:[recordedTmpFile path] error:&error];
//Call the dealloc on the remaining objects.
[recorder dealloc];
recorder = nil;
recordedTmpFile = nil;
}
#end

Answer 1

As you have structured your code now, the audio recording code is completely dependent on the presence of the user interface. As soon as your view controller gets deallocated, the audio recorder gets destroyed, too.
You have to decouple the audio recording code from the user interface code. Create a separate class that contains all properties and functionality that is related to recording. Then create an instance of that class outside your view controller (e.g. in your application delegate) and only pass this object to your view controller. The important thing is that the recorder object is totally unaffected by the presence or absence of the view controller.