目標C函數中的內存泄漏與ARC

Question

這裏是來自MGSpotyViewController庫的函數，但我在問這種情況需要注意什麼。

我習慣於C++和維護我自己的對象，但我在這裏找不到問題。我用UIGraphicsBeginImageContextWithOptions嘗試了非常基本的代碼，內存仍然略有增加，但我不確定是否找到問題或者是因爲GC尚未運行。

測試以下功能我所做的：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 
{ 
    UIImage* image = [UIImage imageNamed:@"Dude.png"]; 

    for (int i =0; i<1000; i++) { 
     @autoreleasepool { 
      // doesn't matter if i move the first line here. 
      UIImage *blurredImage = [image applyBlurWithRadius:20.0f 
               tintColor:nil 
            saturationDeltaFactor:1.0f 
               maskImage:nil]; 
     } 

    } 
} 

結果是這樣的：

是什麼/可能是什麼問題？

的UIImage + ImageEffects.m

- (UIImage *)applyBlurWithRadius:(CGFloat)blurRadius tintColor:(UIColor *)tintColor saturationDeltaFactor:(CGFloat)saturationDeltaFactor maskImage:(UIImage *)maskImage 
{ 
    // Check pre-conditions. 
    if(self.size.width < 1 || self.size.height < 1) { 
     NSLog (@"*** error: invalid size: (%.2f x %.2f). Both dimensions must be >= 1: %@", self.size.width, self.size.height, self); 
     return nil; 
    } 
    if(!self.CGImage) { 
     NSLog (@"*** error: image must be backed by a CGImage: %@", self); 
     return nil; 
    } 
    if(maskImage && !maskImage.CGImage) { 
     NSLog (@"*** error: maskImage must be backed by a CGImage: %@", maskImage); 
     return nil; 
    } 

    CGRect imageRect = { CGPointZero, self.size }; 
    UIImage *effectImage = self; 
    CGFloat scale = 0.5f; 
    scale = [[UIScreen mainScreen] scale]; 

    BOOL hasBlur = blurRadius > __FLT_EPSILON__; 
    BOOL hasSaturationChange = fabs(saturationDeltaFactor - 1.) > __FLT_EPSILON__; 
    if(hasBlur || hasSaturationChange) { 
     UIGraphicsBeginImageContextWithOptions(self.size, NO, scale); 
     CGContextRef effectInContext = UIGraphicsGetCurrentContext(); 
     CGContextScaleCTM(effectInContext, 1.0, -1.0); 
     CGContextTranslateCTM(effectInContext, 0, -self.size.height); 
     CGContextDrawImage(effectInContext, imageRect, self.CGImage); 

     vImage_Buffer effectInBuffer; 
     effectInBuffer.data  = CGBitmapContextGetData(effectInContext); 
     effectInBuffer.width = CGBitmapContextGetWidth(effectInContext); 
     effectInBuffer.height = CGBitmapContextGetHeight(effectInContext); 
     effectInBuffer.rowBytes = CGBitmapContextGetBytesPerRow(effectInContext); 

     UIGraphicsBeginImageContextWithOptions(self.size, NO, scale); 
     CGContextRef effectOutContext = UIGraphicsGetCurrentContext(); 
     vImage_Buffer effectOutBuffer; 
     effectOutBuffer.data  = CGBitmapContextGetData(effectOutContext); 
     effectOutBuffer.width = CGBitmapContextGetWidth(effectOutContext); 
     effectOutBuffer.height = CGBitmapContextGetHeight(effectOutContext); 
     effectOutBuffer.rowBytes = CGBitmapContextGetBytesPerRow(effectOutContext); 

     if(hasBlur) { 
      // A description of how to compute the box kernel width from the Gaussian 
      // radius (aka standard deviation) appears in the SVG spec: 
      // http://www.w3.org/TR/SVG/filters.html#feGaussianBlurElement 
      // 
      // For larger values of 's' (s >= 2.0), an approximation can be used: Three 
      // successive box-blurs build a piece-wise quadratic convolution kernel, which 
      // approximates the Gaussian kernel to within roughly 3%. 
      // 
      // let d = floor(s * 3*sqrt(2*pi)/4 + 0.5) 
      // 
      // ... if d is odd, use three box-blurs of size 'd', centered on the output pixel. 
      // 
      CGFloat inputRadius = blurRadius * scale; 
      NSUInteger radius = floor(inputRadius * 3. * sqrt(2 * M_PI)/4 + 0.5); 
      if(radius % 2 != 1) { 
       radius += 1; // force radius to be odd so that the three box-blur methodology works. 
      } 
      vImageBoxConvolve_ARGB8888(&effectInBuffer, &effectOutBuffer, NULL, 0, 0, (int)radius, (int)radius, 0, kvImageEdgeExtend); 
      vImageBoxConvolve_ARGB8888(&effectOutBuffer, &effectInBuffer, NULL, 0, 0, (int)radius, (int)radius, 0, kvImageEdgeExtend); 
      vImageBoxConvolve_ARGB8888(&effectInBuffer, &effectOutBuffer, NULL, 0, 0, (int)radius, (int)radius, 0, kvImageEdgeExtend); 
     } 
     BOOL effectImageBuffersAreSwapped = NO; 
     if(hasSaturationChange) { 
      CGFloat s = saturationDeltaFactor; 
      CGFloat floatingPointSaturationMatrix[] = { 
       0.0722 + 0.9278 * s, 0.0722 - 0.0722 * s, 0.0722 - 0.0722 * s, 0, 
       0.7152 - 0.7152 * s, 0.7152 + 0.2848 * s, 0.7152 - 0.7152 * s, 0, 
       0.2126 - 0.2126 * s, 0.2126 - 0.2126 * s, 0.2126 + 0.7873 * s, 0, 
            0,     0,     0, 1, 
      }; 
      const int32_t divisor = 256; 
      NSUInteger matrixSize = sizeof(floatingPointSaturationMatrix)/sizeof(floatingPointSaturationMatrix[0]); 
      int16_t saturationMatrix[matrixSize]; 
      for (NSUInteger i = 0; i < matrixSize; ++i) { 
       saturationMatrix[i] = (int16_t)roundf(floatingPointSaturationMatrix[i] * divisor); 
      } 
      if(hasBlur) { 
       vImageMatrixMultiply_ARGB8888(&effectOutBuffer, &effectInBuffer, saturationMatrix, divisor, NULL, NULL, kvImageNoFlags); 
       effectImageBuffersAreSwapped = YES; 
      } 
      else { 
       vImageMatrixMultiply_ARGB8888(&effectInBuffer, &effectOutBuffer, saturationMatrix, divisor, NULL, NULL, kvImageNoFlags); 
      } 
     } 
     if(!effectImageBuffersAreSwapped) 
      effectImage = UIGraphicsGetImageFromCurrentImageContext(); 
     UIGraphicsEndImageContext(); 

     if(effectImageBuffersAreSwapped) 
      effectImage = UIGraphicsGetImageFromCurrentImageContext(); 
     UIGraphicsEndImageContext(); 
    } 

    // Set up output context. 
    UIGraphicsBeginImageContextWithOptions(self.size, NO, scale); 
    CGContextRef outputContext = UIGraphicsGetCurrentContext(); 
    CGContextScaleCTM(outputContext, 1.0, -1.0); 
    CGContextTranslateCTM(outputContext, 0, -self.size.height); 

    // Draw base image. 
    CGContextDrawImage(outputContext, imageRect, self.CGImage); 

    // Draw effect image. 
    if(hasBlur) { 
     CGContextSaveGState(outputContext); 
     if(maskImage) { 
      CGContextClipToMask(outputContext, imageRect, maskImage.CGImage); 
     } 
     CGContextDrawImage(outputContext, imageRect, effectImage.CGImage); 
     CGContextRestoreGState(outputContext); 
    } 

    // Add in color tint. 
    if(tintColor) { 
     CGContextSaveGState(outputContext); 
     CGContextSetFillColorWithColor(outputContext, tintColor.CGColor); 
     CGContextFillRect(outputContext, imageRect); 
     CGContextRestoreGState(outputContext); 
    } 

    // Output image is ready. 
    UIImage *outputImage = UIGraphicsGetImageFromCurrentImageContext(); 
    UIGraphicsEndImageContext(); 

    return outputImage; 
} 

Answer 1

哇，哇。

事實證明，如果該函數的輸入UIImage的比例尺不同於[[UIScreen mainScreen] scale]（因爲我將它設置在函數UIGraphicsBeginImageContextWithOptions中），它會變得瘋狂。

我不知道如何或爲什麼，我不確定即使這可以歸類爲一般問題，但我現在將接受此作爲答案。