iOS sine wave generation - audible clicking

I am in the process of creating a synthesiser for iOS. After playing around and attempting to learn core audio, I have encountered a problem that I cannot get my head around. My sine wave makes a clicking noise on regular intervals, which Im guessing is related to the phase. I have looked at several guides and books on the subject, and all suggest that I am doing it correctly. If anybody would be so kind to look at my code for me it would be greatly appreciated. ``` static OSStatus renderInput(void *inRefCon, AudioUnitRenderActionFlags *ioActionFlags, const AudioTimeStamp *inTimeStamp, UInt32 inBusNumber, UInt32 inNumberFrames, AudioBufferList *ioData) { // Get a reference to the object that was passed with the callback // In this case, the AudioController passed itself so // that you can access its data. AudioController *THIS = (AudioController*)inRefCon; // Get a pointer to the dataBuffer of the AudioBufferList AudioSampleType *outA = (AudioSampleType *)ioData->mBuffers[0].mData; float freq = THIS->Frequency; float phase = THIS->sinPhase; float envValue; float sinSignal; // The amount the phase changes in single sample double phaseIncrement = 2 * M_PI * freq / kGraphSampleRate; // Loop through the callback buffer, generating samples for (UInt32 i = 0; i < inNumberFrames; ++i) { sinSignal = sin(phase); envValue = THIS->env.tick(); // Put the sample into the buffer // Scale the -1 to 1 values float to // -32767 to 32767 and then cast to an integer outA[i] = (SInt16)(((sinSignal * 32767.0f) / 2) * envValue); phase = phase + phaseIncrement; if (phase >= (2 * M_PI * freq)) { phase = phase - (2 * M_PI * freq); } } // Store the phase for the next callback. THIS->sinPhase = phase; return noErr; } ```