iOS系统声音服务(System Sound Services)

系统声音服务(System Sound Services)提供了一个接口，用于播放不超过30秒的声音。它支持的文件格式有限，具体地说只有CAF、AIF和使用PCM或IMA/ADPCM数据的WAV文件。由于这些函数没有提供操纵声音和控制音量的功能，所以当你为多媒体或者游戏创建专门的配乐时，不要使用系统声音服务。

iOS使用系统声音服务来支持三种不同的通知：
1. 声音：立刻播放一个简单的声音文件。如果手机被设置为静音，用户什么也听不到
2. 提醒：播放一个声音文件，如果手机被设置为静音或震动，将通过震动提醒用户
3. 震动：震动手机，而不考虑其他设置

要在项目中使用系统声音服务，首先在自己的工程中添加AudioToolbox.framework库，在.m文件中添加头文件：要导入AudioToolbox.h

#import <AudioToolbox/AudioToolbox.h>

系统声音服务并非是通过类实现的，而是使用传统的C语言函数调用来触发播放操作。要播放音频，需要使用的两个函数是AudioServicesCreateSystemSoundID 和 AudioServicesPlaySystemSound。还需要声明一个类型为SystemSoundID的变量，它表示要使用的声音文件。下面演示了如何加载并播放声音：

然后在需要打开声音的地方添加代码：AudioServicesPlaySystemSound(audioID);

其中audioID就是你需要打开系统声音的id号：附上系统对应提示音对照表：

There are some predefined system sounds, for the system sound ID in the range 1000 to 2000 (decimal), as shown below (from 2.0 to 5.0 beta). The system sounds are all stored in/System/Library/Audio/UISounds/.

Sound ID	File name (iPhone)	File name (iPod Touch)	Category	Note
1000	new-mail.caf	new-mail.caf	MailReceived
1001	mail-sent.caf	mail-sent.caf	MailSent
1002	Voicemail.caf	Voicemail.caf	VoicemailReceived
1003	ReceivedMessage.caf	ReceivedMessage.caf	SMSReceived
1004	SentMessage.caf	SentMessage.caf	SMSSent
1005	alarm.caf	sq_alarm.caf	CalendarAlert
1006	low_power.caf	low_power.caf	LowPower
1007	sms-received1.caf	sms-received1.caf	SMSReceived_Alert
1008	sms-received2.caf	sms-received2.caf	SMSReceived_Alert
1009	sms-received3.caf	sms-received3.caf	SMSReceived_Alert
1010	sms-received4.caf	sms-received4.caf	SMSReceived_Alert
1011	-	-	SMSReceived_Vibrate
1012	sms-received1.caf	sms-received1.caf	SMSReceived_Alert
1013	sms-received5.caf	sms-received5.caf	SMSReceived_Alert
1014	sms-received6.caf	sms-received6.caf	SMSReceived_Alert
1015	Voicemail.caf	Voicemail.caf	-	Available since 2.1
1016	tweet_sent.caf	tweet_sent.caf	SMSSent	Available since 5.0
1020	Anticipate.caf	Anticipate.caf	SMSReceived_Alert	Available since 4.2
1021	Bloom.caf	Bloom.caf	SMSReceived_Alert	Available since 4.2
1022	Calypso.caf	Calypso.caf	SMSReceived_Alert	Available since 4.2
1023	Choo_Choo.caf	Choo_Choo.caf	SMSReceived_Alert	Available since 4.2
1024	Descent.caf	Descent.caf	SMSReceived_Alert	Available since 4.2
1025	Fanfare.caf	Fanfare.caf	SMSReceived_Alert	Available since 4.2
1026	Ladder.caf	Ladder.caf	SMSReceived_Alert	Available since 4.2
1027	Minuet.caf	Minuet.caf	SMSReceived_Alert	Available since 4.2
1028	News_Flash.caf	News_Flash.caf	SMSReceived_Alert	Available since 4.2
1029	Noir.caf	Noir.caf	SMSReceived_Alert	Available since 4.2
1030	Sherwood_Forest.caf	Sherwood_Forest.caf	SMSReceived_Alert	Available since 4.2
1031	Spell.caf	Spell.caf	SMSReceived_Alert	Available since 4.2
1032	Suspense.caf	Suspense.caf	SMSReceived_Alert	Available since 4.2
1033	Telegraph.caf	Telegraph.caf	SMSReceived_Alert	Available since 4.2
1034	Tiptoes.caf	Tiptoes.caf	SMSReceived_Alert	Available since 4.2
1035	Typewriters.caf	Typewriters.caf	SMSReceived_Alert	Available since 4.2
1036	Update.caf	Update.caf	SMSReceived_Alert	Available since 4.2
1050	ussd.caf	ussd.caf	USSDAlert
1051	SIMToolkitCallDropped.caf	SIMToolkitCallDropped.caf	SIMToolkitTone
1052	SIMToolkitGeneralBeep.caf	SIMToolkitGeneralBeep.caf	SIMToolkitTone
1053	SIMToolkitNegativeACK.caf	SIMToolkitNegativeACK.caf	SIMToolkitTone
1054	SIMToolkitPositiveACK.caf	SIMToolkitPositiveACK.caf	SIMToolkitTone
1055	SIMToolkitSMS.caf	SIMToolkitSMS.caf	SIMToolkitTone
1057	Tink.caf	Tink.caf	PINKeyPressed
1070	ct-busy.caf	ct-busy.caf	AudioToneBusy	There was no category for this sound before 4.0.
1071	ct-congestion.caf	ct-congestion.caf	AudioToneCongestion	There was no category for this sound before 4.0.
1072	ct-path-ack.caf	ct-path-ack.caf	AudioTonePathAcknowledge	There was no category for this sound before 4.0.
1073	ct-error.caf	ct-error.caf	AudioToneError	There was no category for this sound before 4.0.
1074	ct-call-waiting.caf	ct-call-waiting.caf	AudioToneCallWaiting	There was no category for this sound before 4.0.
1075	ct-keytone2.caf	ct-keytone2.caf	AudioToneKey2	There was no category for this sound before 4.0.
1100	lock.caf	sq_lock.caf	ScreenLocked
1101	unlock.caf	sq_lock.caf	ScreenUnlocked
1102	-	-	FailedUnlock
1103	Tink.caf	sq_tock.caf	KeyPressed
1104	Tock.caf	sq_tock.caf	KeyPressed
1105	Tock.caf	sq_tock.caf	KeyPressed
1106	beep-beep.caf	sq_beep-beep.caf	ConnectedToPower
1107	RingerChanged.caf	RingerChanged.caf	RingerSwitchIndication
1108	photoShutter.caf	photoShutter.caf	CameraShutter
1109	shake.caf	shake.caf	ShakeToShuffle	Available since 3.0
1110	jbl_begin.caf	jbl_begin.caf	JBL_Begin	Available since 3.0
1111	jbl_confirm.caf	jbl_confirm.caf	JBL_Confirm	Available since 3.0
1112	jbl_cancel.caf	jbl_cancel.caf	JBL_Cancel	Available since 3.0
1113	begin_record.caf	begin_record.caf	BeginRecording	Available since 3.0
1114	end_record.caf	end_record.caf	EndRecording	Available since 3.0
1115	jbl_ambiguous.caf	jbl_ambiguous.caf	JBL_Ambiguous	Available since 3.0
1116	jbl_no_match.caf	jbl_no_match.caf	JBL_NoMatch	Available since 3.0
1117	begin_video_record.caf	begin_video_record.caf	BeginVideoRecording	Available since 3.0
1118	end_video_record.caf	end_video_record.caf	EndVideoRecording	Available since 3.0
1150	vc~invitation-accepted.caf	vc~invitation-accepted.caf	VCInvitationAccepted	Available since 4.0
1151	vc~ringing.caf	vc~ringing.caf	VCRinging	Available since 4.0
1152	vc~ended.caf	vc~ended.caf	VCEnded	Available since 4.0
1153	ct-call-waiting.caf	ct-call-waiting.caf	VCCallWaiting	Available since 4.1
1154	vc~ringing.caf	vc~ringing.caf	VCCallUpgrade	Available since 4.1
1200	dtmf-0.caf	dtmf-0.caf	TouchTone
1201	dtmf-1.caf	dtmf-1.caf	TouchTone
1202	dtmf-2.caf	dtmf-2.caf	TouchTone
1203	dtmf-3.caf	dtmf-3.caf	TouchTone
1204	dtmf-4.caf	dtmf-4.caf	TouchTone
1205	dtmf-5.caf	dtmf-5.caf	TouchTone
1206	dtmf-6.caf	dtmf-6.caf	TouchTone
1207	dtmf-7.caf	dtmf-7.caf	TouchTone
1208	dtmf-8.caf	dtmf-8.caf	TouchTone
1209	dtmf-9.caf	dtmf-9.caf	TouchTone
1210	dtmf-star.caf	dtmf-star.caf	TouchTone
1211	dtmf-pound.caf	dtmf-pound.caf	TouchTone
1254	long_low_short_high.caf	long_low_short_high.caf	Headset_StartCall
1255	short_double_high.caf	short_double_high.caf	Headset_Redial
1256	short_low_high.caf	short_low_high.caf	Headset_AnswerCall
1257	short_double_low.caf	short_double_low.caf	Headset_EndCall
1258	short_double_low.caf	short_double_low.caf	Headset_CallWaitingActions
1259	middle_9_short_double_low.caf	middle_9_short_double_low.caf	Headset_TransitionEnd
1300	Voicemail.caf	Voicemail.caf	SystemSoundPreview
1301	ReceivedMessage.caf	ReceivedMessage.caf	SystemSoundPreview
1302	new-mail.caf	new-mail.caf	SystemSoundPreview
1303	mail-sent.caf	mail-sent.caf	SystemSoundPreview
1304	alarm.caf	sq_alarm.caf	SystemSoundPreview
1305	lock.caf	sq_lock.caf	SystemSoundPreview
1306	Tock.caf	sq_tock.caf	KeyPressClickPreview	The category was SystemSoundPreview before 3.2.
1307	sms-received1.caf	sms-received1.caf	SMSReceived_Selection
1308	sms-received2.caf	sms-received2.caf	SMSReceived_Selection
1309	sms-received3.caf	sms-received3.caf	SMSReceived_Selection
1310	sms-received4.caf	sms-received4.caf	SMSReceived_Selection
1311	-	-	SMSReceived_Vibrate
1312	sms-received1.caf	sms-received1.caf	SMSReceived_Selection
1313	sms-received5.caf	sms-received5.caf	SMSReceived_Selection
1314	sms-received6.caf	sms-received6.caf	SMSReceived_Selection
1315	Voicemail.caf	Voicemail.caf	SystemSoundPreview	Available since 2.1
1320	Anticipate.caf	Anticipate.caf	SMSReceived_Selection	Available since 4.2
1321	Bloom.caf	Bloom.caf	SMSReceived_Selection	Available since 4.2
1322	Calypso.caf	Calypso.caf	SMSReceived_Selection	Available since 4.2
1323	Choo_Choo.caf	Choo_Choo.caf	SMSReceived_Selection	Available since 4.2
1324	Descent.caf	Descent.caf	SMSReceived_Selection	Available since 4.2
1325	Fanfare.caf	Fanfare.caf	SMSReceived_Selection	Available since 4.2
1326	Ladder.caf	Ladder.caf	SMSReceived_Selection	Available since 4.2
1327	Minuet.caf	Minuet.caf	SMSReceived_Selection	Available since 4.2
1328	News_Flash.caf	News_Flash.caf	SMSReceived_Selection	Available since 4.2
1329	Noir.caf	Noir.caf	SMSReceived_Selection	Available since 4.2
1330	Sherwood_Forest.caf	Sherwood_Forest.caf	SMSReceived_Selection	Available since 4.2
1331	Spell.caf	Spell.caf	SMSReceived_Selection	Available since 4.2
1332	Suspense.caf	Suspense.caf	SMSReceived_Selection	Available since 4.2
1333	Telegraph.caf	Telegraph.caf	SMSReceived_Selection	Available since 4.2
1334	Tiptoes.caf	Tiptoes.caf	SMSReceived_Selection	Available since 4.2
1335	Typewriters.caf	Typewriters.caf	SMSReceived_Selection	Available since 4.2
1336	Update.caf	Update.caf	SMSReceived_Selection	Available since 4.2
1350	-	-	RingerVibeChanged
1351	-	-	SilentVibeChanged
4095	-	-	Vibrate	There was no category for this sound before 2.2. In the SDK this is the constant kSystemSoundID_Vibrate.

当然你可以定义自己的提示音，打开自己工程中的音频文件，代码如下:

static SystemSoundID _ringSystemSoundID;

static void ringAudioServicesSystemSoundCompletionProc(SystemSoundID ssID, void *clientData)

{

    AudioServicesPlayAlertSound(ssID);

}

void ringStartRing()

{

    // 获取文件所在的路径
    NSString *path = [NSString stringWithFormat:@"%@%@", [[NSBundle mainBundle] resourcePath], @"/jad0007a.wav"];

    [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategorySoloAmbient

                                           error:nil];

    //利用打开的文件创建一个soundID

    AudioServicesCreateSystemSoundID((__bridge CFURLRef) path, &_ringSystemSoundID);

    //当声音播放完后的回调函数，完成后将调用ringAudioServicesSystemSoundCompletionProc函数进行循环播放

    AudioServicesAddSystemSoundCompletion(_ringSystemSoundID, NULL, NULL, ringAudioServicesSystemSoundCompletionProc, NULL);

    //通过创建的soundID打开对应的音频文件

    AudioServicesPlayAlertSound(_ringSystemSoundID);

}

通过调用AudioServicesAddSystemSoundCompletion 添加可选的系统声音完成回调，通知你的程序声音已经播放完毕。如果你不使用一个接一个的短声音，那么一般可以跳过该步骤。

void ringStopRing()

{

    if (_ringSystemSoundID != 0) {

        //移除系统播放完成后的回调函数

        AudioServicesRemoveSystemSoundCompletion(_ringSystemSoundID);

        //销毁创建的SoundID

        AudioServicesDisposeSystemSoundID(_ringSystemSoundID);

        _ringSystemSoundID = 0;

    }

}

调用 AudioServicesDisposeSystemSoundID 以及相应的声音可以清除你的声音，该操作可以释放声音对象以及相关的所有资源

对于提醒音来说，与系统声音之间的差别在于，如果手机处于静音状态，提醒音将自动触发震动。提醒音的设置和用法与系统声音相同，区别在于系统声音调用AudioServicesPlaySystemSound，而提醒音调用AudioServicesPlayAlertSound。

震动更容易实现，只需要调用AudioServicesPlaySystemSound，并将常量kSystemSoundID_Vibrate传递给它：

AudioServicesPlaySystemSound(kSystemSoundID_Vibrate);

如果视图震动不支持震动的设备(如iPad2)，将静默失败。因此将震动代码留在应用程序中不会有任何害处，而不管目标设备是什么。

////////////

AVAudioPlayer和SystemSoundService。这两种功能在一定程度上都适合作为游戏音效的播放方式。而两者也各有其优缺点。下面我们来总结一下有哪些：

1）AVAudioPlayer的优点

（1）可以播放任意长度音乐；

（2）可以循环播放；

（3）可以控制播放的时间；

（4）可以控制声道的音量实现立体声效果；

（5）可以调整音量。

2）AVAudioPlayer的缺点

（1）播放之前必须先加载，不能立即播放；

（2）一次一个AudioPlayer只能播放所加载的音乐，不能同时播放好几次同样的音乐。

（3）没有振动效果

3）SystemSoundService的优点：

（1）能够立即播放

（2）能够在同一时间播放多次音乐

（3）可以加上振动效果

4）SystemSoundService的缺点：

（1）不能循环播放

（2）不能控制播放时间

（3）不能控制声道

（4）不能控制音量

（5）不能暂停音乐

因此，我们可以考虑综合两者的功能！