error in audio Unit code -remoteIO for iphone - objective-c

Question

i have this code, in order to read buffer samples , but i get a strange mach-o linker error ,
Framework of audio unit couldnt loaded so i put the audioTollBox and coreAudio as i read.
my code is :
#define kOutputBus 0
#define kInputBus 1
AudioComponentInstance audioUnit;
#implementation remoteIO
//callback function :
static OSStatus recordingCallback(void *inRefCon,
AudioUnitRenderActionFlags *ioActionFlags,
const AudioTimeStamp *inTimeStamp,
UInt32 inBusNumber,
UInt32 inNumberFrames,
AudioBufferList *ioData)
{
AudioBuffer buffer;
buffer.mNumberChannels = 1;
buffer.mDataByteSize = inNumberFrames * 2;
NSLog(#"%ld",inNumberFrames);
buffer.mData = malloc( inNumberFrames * 2 );
AudioBufferList bufferList;
bufferList.mNumberBuffers = 1;
bufferList.mBuffers[0] = buffer;
OSStatus status;
status = AudioUnitRender(audioUnit,
ioActionFlags,
inTimeStamp,
inBusNumber,
inNumberFrames,
&bufferList);
checkStatus(status); //here is the warnning+error
double *q = (double *)(&bufferList)->mBuffers[0].mData;
for(int i=0; i < strlen((const char *)(&bufferList)->mBuffers[0].mData); i++)
{
NSLog(#"%f",q[i]);
}
}
and the reading method :
-(void)startListeningWithFrequency:(float)freq;
{
OSStatus status;
AudioComponentDescription desc;
desc.componentType = kAudioUnitType_Output;
desc.componentSubType = kAudioUnitSubType_RemoteIO;
desc.componentFlags = 0;
desc.componentFlagsMask = 0;
desc.componentManufacturer = kAudioUnitManufacturer_Apple;
AudioComponent inputComponent = AudioComponentFindNext(NULL, &desc);
status = AudioComponentInstanceNew( inputComponent, &audioUnit);
checkStatus(status);
UInt32 flag = 1;
status = AudioUnitSetProperty(audioUnit, kAudioOutputUnitProperty_EnableIO, kAudioUnitScope_Input,kInputBus, &flag, sizeof(flag));
checkStatus(status);
AudioStreamBasicDescription audioFormat;
audioFormat.mSampleRate = 44100.00;//44100.00;
audioFormat.mFormatID = kAudioFormatLinearPCM;
audioFormat.mFormatFlags = kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsPacked;
audioFormat.mFramesPerPacket = 1;
audioFormat.mChannelsPerFrame = 1;
audioFormat.mBitsPerChannel = 16;
audioFormat.mBytesPerPacket = 2;
audioFormat.mBytesPerFrame = 2;
status = AudioUnitSetProperty(audioUnit,
kAudioUnitProperty_StreamFormat,
kAudioUnitScope_Output,
kInputBus,
&audioFormat,
sizeof(audioFormat));
checkStatus(status);
checkStatus(status);
AURenderCallbackStruct callbackStruct;
callbackStruct.inputProc = recordingCallback;
callbackStruct.inputProcRefCon = self;
status = AudioUnitSetProperty(audioUnit,
kAudioOutputUnitProperty_SetInputCallback,
kAudioUnitScope_Global,
kInputBus, &callbackStruct, sizeof(callbackStruct));
checkStatus(status);
status = AudioOutputUnitStart(audioUnit);
}
and what i get is this error and warnning :
Undefined symbols for architecture i386:
"_checkStatus", referenced from:
_recordingCallback in remoteIO.o
-[remoteIO startListeningWithFrequency:] in remoteIO.o
ld: symbol(s) not found for architecture i386
collect2: ld returned 1 exit status
whats wrong here, ?
thanks.

Answer 1

You have to write your own checkStatus() function, as what it does (e.g. how it reports an error: dialog box, console output, analytics logging, crash dump, etc.), or whether is does anything at all other than return from the audio code, is specific to each app.