/* |
File: MixerHostViewController.m |
Abstract: View controller: Sets up the user interface and conveys UI actions |
to the MixerHostAudio object. Also responds to state-change notifications from |
the MixerHostAudio object. |
Version: 1.0 |
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IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL |
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Copyright (C) 2010 Apple Inc. All Rights Reserved. |
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*/ |
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#import "MixerHostViewController.h" |
#import "MixerHostAudio.h" |
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NSString *MixerHostAudioObjectPlaybackStateDidChangeNotification = @"MixerHostAudioObjectPlaybackStateDidChangeNotification"; |
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@implementation MixerHostViewController |
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// To learn about properties, see "Declared Properties" in the "Cocoa Objects" chapter |
// in Cocoa Fundamentals Guide |
@synthesize playButton; |
@synthesize mixerBus0Switch; |
@synthesize mixerBus0LevelFader; |
@synthesize mixerBus1Switch; |
@synthesize mixerBus1LevelFader; |
@synthesize mixerOutputLevelFader; |
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@synthesize audioObject; |
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# pragma mark - |
# pragma mark User interface methods |
// Set the initial multichannel mixer unit parameter values according to the UI state |
- (void) initializeMixerSettingsToUI { |
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// Initialize mixer settings to UI |
[audioObject enableMixerInput: 0 isOn: mixerBus0Switch.isOn]; |
[audioObject enableMixerInput: 1 isOn: mixerBus1Switch.isOn]; |
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[audioObject setMixerOutputGain: mixerOutputLevelFader.value]; |
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[audioObject setMixerInput: 0 gain: mixerBus0LevelFader.value]; |
[audioObject setMixerInput: 1 gain: mixerBus1LevelFader.value]; |
} |
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// Handle a change in the mixer output gain slider. |
- (IBAction) mixerOutputGainChanged: (UISlider *) sender { |
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[audioObject setMixerOutputGain: (AudioUnitParameterValue) sender.value]; |
} |
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// Handle a change in a mixer input gain slider. The "tag" value of the slider lets this |
// method distinguish between the two channels. |
- (IBAction) mixerInputGainChanged: (UISlider *) sender { |
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UInt32 inputBus = sender.tag; |
[audioObject setMixerInput: (UInt32) inputBus gain: (AudioUnitParameterValue) sender.value]; |
} |
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#pragma mark - |
#pragma mark Audio processing graph control |
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// Handle a play/stop button tap |
- (IBAction) playOrStop: (id) sender { |
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if (audioObject.isPlaying) { |
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[audioObject stopAUGraph]; |
self.playButton.title = @"Play"; |
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} else { |
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[audioObject startAUGraph]; |
self.playButton.title = @"Stop"; |
} |
} |
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// Handle a change in playback state that resulted from an audio session interruption or end of interruption |
- (void) handlePlaybackStateChanged: (id) notification { |
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[self playOrStop: nil]; |
} |
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#pragma mark - |
#pragma mark Mixer unit control |
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// Handle a Mixer unit input on/off switch action. The "tag" value of the switch lets this |
// method distinguish between the two channels. |
- (IBAction) enableMixerInput: (UISwitch *) sender { |
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UInt32 inputBus = sender.tag; |
AudioUnitParameterValue isOn = (AudioUnitParameterValue) sender.isOn; |
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[audioObject enableMixerInput: inputBus isOn: isOn]; |
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} |
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#pragma mark - |
#pragma mark Remote-control event handling |
// Respond to remote control events |
- (void) remoteControlReceivedWithEvent: (UIEvent *) receivedEvent { |
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if (receivedEvent.type == UIEventTypeRemoteControl) { |
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switch (receivedEvent.subtype) { |
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case UIEventSubtypeRemoteControlTogglePlayPause: |
[self playOrStop: nil]; |
break; |
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default: |
break; |
} |
} |
} |
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#pragma mark - |
#pragma mark Notification registration |
// If this app's audio session is interrupted when playing audio, it needs to update its user interface |
// to reflect the fact that audio has stopped. The MixerHostAudio object conveys its change in state to |
// this object by way of a notification. To learn about notifications, see Notification Programming Topics. |
- (void) registerForAudioObjectNotifications { |
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NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter]; |
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[notificationCenter addObserver: self |
selector: @selector (handlePlaybackStateChanged:) |
name: MixerHostAudioObjectPlaybackStateDidChangeNotification |
object: audioObject]; |
} |
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#pragma mark - |
#pragma mark Application state management |
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- (void) viewDidLoad { |
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[super viewDidLoad]; |
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MixerHostAudio *newAudioObject = [[MixerHostAudio alloc] init]; |
self.audioObject = newAudioObject; |
[newAudioObject release]; |
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[self registerForAudioObjectNotifications]; |
[self initializeMixerSettingsToUI]; |
} |
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// If using a nonmixable audio session category, as this app does, you must activate reception of |
// remote-control events to allow reactivation of the audio session when running in the background. |
// Also, to receive remote-control events, the app must be eligible to become the first responder. |
- (void) viewDidAppear: (BOOL) animated { |
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[super viewDidAppear: animated]; |
[[UIApplication sharedApplication] beginReceivingRemoteControlEvents]; |
[self becomeFirstResponder]; |
} |
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- (BOOL) canBecomeFirstResponder { |
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return YES; |
} |
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- (void) didReceiveMemoryWarning { |
// Releases the view if it doesn't have a superview. |
[super didReceiveMemoryWarning]; |
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// Release any cached data, images, etc that aren't in use. |
} |
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- (void) viewWillDisppear: (BOOL) animated { |
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[[UIApplication sharedApplication] endReceivingRemoteControlEvents]; |
[self resignFirstResponder]; |
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[super viewWillDisappear: animated]; |
} |
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- (void) viewDidUnload { |
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self.playButton = nil; |
self.mixerBus0Switch = nil; |
self.mixerBus1Switch = nil; |
self.mixerBus0LevelFader = nil; |
self.mixerBus1LevelFader = nil; |
self.mixerOutputLevelFader = nil; |
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[[NSNotificationCenter defaultCenter] removeObserver: self |
name: MixerHostAudioObjectPlaybackStateDidChangeNotification |
object: audioObject]; |
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self.audioObject = nil; |
[super viewDidUnload]; |
} |
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- (void) dealloc { |
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[playButton release]; |
[mixerBus0Switch release]; |
[mixerBus1Switch release]; |
[mixerBus0LevelFader release]; |
[mixerBus1LevelFader release]; |
[mixerOutputLevelFader release]; |
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[[NSNotificationCenter defaultCenter] removeObserver: self |
name: MixerHostAudioObjectPlaybackStateDidChangeNotification |
object: audioObject]; |
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[audioObject release]; |
[[UIApplication sharedApplication] endReceivingRemoteControlEvents]; |
[super dealloc]; |
} |
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@end |