Invalid Identifier with NSRect frame = [self frame]

I'm currently trying to figure out how to alter frames from a webcam for a motion detection game. I am very new to Objective-C, and I have been unable to find a simple way to do this.

My question here is about an error message related to this method:

- (void)captureOutput:(QTCaptureOutput *)captureOutput 
  didOutputVideoFrame:(CVImageBufferRef)videoFrame
     withSampleBuffer:(QTSampleBuffer *)sampleBuffer 
       fromConnection:(QTCaptureConnection *)connection
{


    CIContext *myCIContext;
    const NSOpenGLPixelFormatAttribute attr[] = {
        NSOpenGLPFAAccelerated,
        NSOpenGLPFANoRecovery,
        NSOpenGLPFAColorSize, 32,
        0
    };
    NSOpenGLPixelFormat *pf = [[NSOpenGLPixelFormat alloc] initWithAttributes:(void *)&attr];
    myCIContext = [CIContext contextWithCGLContext: CGLGetCurrentContext()
                                       pixelFormat: [pf CGLPixelFormatObj]
                                           options: nil];
    CVImageBufferRef releasedImageBuffer;
    CVBufferRetain(videoFrame);

    CIImage *picture = [CIImage imageWithCVImageBuffer:releasedImageBuffer];
    NSRect frame = [self frame];
    CGRect imageRect;
    imageRect = [picture extent];

    [colorCorrectionFilter setValue:picture forKey:@"inputImage"];
    [effectFilter setValue:[colorCorrectionFilter valueForKey:@"outputImage"] forKey:@"inputImage"];

    // render our resulting image into our context
    [ciContext drawImage:[compositeFilter valueForKey:@"outputImage"] 
                 atPoint:CGPointMake((int)((frame.size.width - imageRect.size.width) * 0.5), (int)((frame.size.height - imageRect.size.height) * 0.5)) // use integer coordinates to avoid interpolation
                fromRect:imageRect];

    @synchronized(self)
    {
        //basically, have frame to be released refer to the current frame
        //then update the reference to the current frame with the next frame in the "video stream"
        releasedImageBuffer = mCurrentImageBuf开发者_高级运维fer;
        mCurrentImageBuffer = videoFrame;
    }

    CVBufferRelease(releasedImageBuffer);

}

The error message produced says:

warning: 'MyRecorderController' may not respond to '-frame'
error: invalid initializer

and the line highlighted is

NSRect frame = [self frame];

My header is currently like so:

#import <QuickTime/ImageCompression.h>
#import <QuickTime/QuickTime.h>
#import <Cocoa/Cocoa.h>
#import <QTKit/QTKit.h>
#import <OpenGL/OpenGL.h>
#import <QuartzCore/QuartzCore.h>
#import <CoreVideo/CoreVideo.h>


@interface MyRecorderController : NSObject{ 
    IBOutlet QTCaptureView *mCaptureView;

    IBOutlet NSPopUpButton *videoDevicePopUp;
    NSMutableDictionary *namesToDevicesDictionary;
    NSString *defaultDeviceMenuTitle;

    CVImageBufferRef mCurrentImageBuffer;
    QTCaptureDecompressedVideoOutput *mCaptureDecompressedVideoOutput;

    // filters for CI rendering
    CIFilter            *colorCorrectionFilter; // hue saturation brightness control through one CI filter
    CIFilter            *effectFilter;          // zoom blur filter
    CIFilter            *compositeFilter;       // composites the timecode over the video
    CIContext           *ciContext;

    QTCaptureSession *mCaptureSession;
    QTCaptureMovieFileOutput *mCaptureMovieFileOutput;
    QTCaptureDeviceInput *mCaptureDeviceInput;

}

@end

I have looked at tutorial code, and I do not understand what I have done wrong. As far as I can see (judging by said various sample code) I should not need to include a protocol in this - which is what other websites have suggested. I have tried it though, and while it does compile it ends up outputting:

2011-01-18 10:19:11.511 MyRecorder[9972:c903] -[MyRecorderController frame]: unrecognized selector sent to instance 0x1001525f0
2011-01-18 10:19:11.512 MyRecorder[9972:c903] *** Ignoring exception: -[MyRecorderController frame]: unrecognized selector sent to instance 0x1001525f0

Is there anything I have done wrong which has caused this? If not, is there a better way to be able to manipulate frames from a webcam (and output them to the screen)?

Thanks heaps!

You are trying to call a method frame on MyRecorderController - which just doesn't have that method. Maybe that class should inherit from UIView, or you need to implement that method.

Ask yourself what frame you mean, and write the appropriate method.