Question

I have a int variable called recordingStatus.
I would like to “listen” to this recording status and update my label based on the status of this variable.

int recordingStatus;

@property (strong, nonatomic) IBOutlet UILabel *recordingStatusText;

The reason I have to do so is that recordingStatus is being changed in my C code (also in the same file) and the C code doesn’t have access to the UI elements (as far as I know).

What’s the most elegant way to do this in iOS?

C Code Core Audio Callback

static OSStatus rioRecordingCallback(void *inRefCon,
                              AudioUnitRenderActionFlags *ioActionFlags,
                              const AudioTimeStamp *inTimeStamp,
                              UInt32 inBusNumber,
                              UInt32 inNumberFrames,
                              AudioBufferList *ioData) {

// want to access recordingStatus in here, am I able to do it without passsing it in via inRefCon?
}

Thanks.

Pier.

Answer 1

There are multiple ways you can approach this. As Rickay noted, you can make it a property and just override the setters to set the value of your label as well.

The other approach is to use KVO to monitor recordingStatus (it will still need to have a property). If you’re looking for a super awesome way to use KVO, check out ReactiveCocoa. This type of observe-react pattern is known as reactive programming.