iphone - Arc で SquareCamController Apple サンプル デモ プロジェクトを停止するにはどうすればよいですか?

Question

私のアプリでは、顔検出のためにアップルが提供するサンプルコードを使用しています。コードは ARC より前に作成されたものであり、アーク以外のコードが多数含まれています。プロジェクトを Arc 用に変換し、ARC プロジェクトで正常に動作しました。唯一の問題は、そのクラスの nslog ステートメントがまだ実行されているのを確認でき、数分後にアプリがクラッシュすることです。ブレークポイントを配置すると、そのクラスでも停止します。つまり、ビューが閉じられた後もバックグラウンドで実行されているため、最終的にクラッシュします。

クラッシュするコードは次のとおりです。

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection
{   
    // got an image
    CVPixelBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
    CFDictionaryRef attachments = CMCopyDictionaryOfAttachments(kCFAllocatorDefault, sampleBuffer, kCMAttachmentMode_ShouldPropagate);
    CIImage *ciImage = [[CIImage alloc] initWithCVPixelBuffer:pixelBuffer options:(__bridge NSDictionary *)attachments];
    if (attachments)
        CFRelease(attachments);
    NSDictionary *imageOptions = nil;
    UIDeviceOrientation curDeviceOrientation = [[UIDevice currentDevice] orientation];
    int exifOrientation;

    /* kCGImagePropertyOrientation values
        The intended display orientation of the image. If present, this key is a CFNumber value with the same value as defined
        by the TIFF and EXIF specifications -- see enumeration of integer constants. 
        The value specified where the origin (0,0) of the image is located. If not present, a value of 1 is assumed.

        used when calling featuresInImage: options: The value for this key is an integer NSNumber from 1..8 as found in kCGImagePropertyOrientation.
        If present, the detection will be done based on that orientation but the coordinates in the returned features will still be based on those of the image. */

    enum {
        PHOTOS_EXIF_0ROW_TOP_0COL_LEFT          = 1, //   1  =  0th row is at the top, and 0th column is on the left (THE DEFAULT).
        PHOTOS_EXIF_0ROW_TOP_0COL_RIGHT         = 2, //   2  =  0th row is at the top, and 0th column is on the right.  
        PHOTOS_EXIF_0ROW_BOTTOM_0COL_RIGHT      = 3, //   3  =  0th row is at the bottom, and 0th column is on the right.  
        PHOTOS_EXIF_0ROW_BOTTOM_0COL_LEFT       = 4, //   4  =  0th row is at the bottom, and 0th column is on the left.  
        PHOTOS_EXIF_0ROW_LEFT_0COL_TOP          = 5, //   5  =  0th row is on the left, and 0th column is the top.  
        PHOTOS_EXIF_0ROW_RIGHT_0COL_TOP         = 6, //   6  =  0th row is on the right, and 0th column is the top.  
        PHOTOS_EXIF_0ROW_RIGHT_0COL_BOTTOM      = 7, //   7  =  0th row is on the right, and 0th column is the bottom.  
        PHOTOS_EXIF_0ROW_LEFT_0COL_BOTTOM       = 8  //   8  =  0th row is on the left, and 0th column is the bottom.  
    };

    switch (curDeviceOrientation) {
        case UIDeviceOrientationPortraitUpsideDown:  // Device oriented vertically, home button on the top
            exifOrientation = PHOTOS_EXIF_0ROW_LEFT_0COL_BOTTOM;
            break;
        case UIDeviceOrientationLandscapeLeft:       // Device oriented horizontally, home button on the right
            if (isUsingFrontFacingCamera)
                exifOrientation = PHOTOS_EXIF_0ROW_BOTTOM_0COL_RIGHT;
            else
                exifOrientation = PHOTOS_EXIF_0ROW_TOP_0COL_LEFT;
            break;
        case UIDeviceOrientationLandscapeRight:      // Device oriented horizontally, home button on the left
            if (isUsingFrontFacingCamera)
                exifOrientation = PHOTOS_EXIF_0ROW_TOP_0COL_LEFT;
            else
                exifOrientation = PHOTOS_EXIF_0ROW_BOTTOM_0COL_RIGHT;
            break;
        case UIDeviceOrientationPortrait:            // Device oriented vertically, home button on the bottom
        default:
            exifOrientation = PHOTOS_EXIF_0ROW_RIGHT_0COL_TOP;
            break;
    }

    imageOptions = [NSDictionary dictionaryWithObject:[NSNumber numberWithInt:exifOrientation] forKey:CIDetectorImageOrientation];
    NSArray *features = [faceDetector featuresInImage:ciImage options:imageOptions];

    // get the clean aperture
    // the clean aperture is a rectangle that defines the portion of the encoded pixel dimensions
    // that represents image data valid for display.
    CMFormatDescriptionRef fdesc = CMSampleBufferGetFormatDescription(sampleBuffer);
    CGRect clap = CMVideoFormatDescriptionGetCleanAperture(fdesc, false /*originIsTopLeft == false*/);

    dispatch_async(dispatch_get_main_queue(), ^(void) {
        [self drawFaceBoxesForFeatures:features forVideoBox:clap orientation:curDeviceOrientation]; --------->>>>>> Its crashing here
    });
}