iPhone 创建自定义图像会导致内存泄漏

Question

我有一个代码，每次用户稍微移动滑块并将其添加到子图层时都会生成新图像。它可以工作，只是它会泄漏内存。我保留了我不应该保留的东西？但是我认为我应该释放一切：

UISlider *slider = (UISlider *)sender;
int progressAsInt = (int)(slider.value);

//add moon mask
UIGraphicsBeginImageContextWithOptions(CGSizeMake(400, 400), NO, 1);
CGContextRef contextRef = UIGraphicsGetCurrentContext();
CGContextSetRGBFillColor(contextRef, 0, 0, 0, 0.8);
CGContextSetRGBStrokeColor(contextRef, 0, 0, 0, 0.8);
int tempx = progressAsInt;
int x = tempx; 
if (x < 0) {
    isHigherThanHalf = YES;
    x = -tempx;
}
else {
    isHigherThanHalf = NO;
}

CGContextSaveGState(contextRef);
BOOL onlyDrawTopHalf = isHigherThanHalf;
CGFloat halfMultiplier = onlyDrawTopHalf ? -1.0 : 1.0;
CGRect ellipse = CGRectMake(200-x/2, 0, 0+x, 400);

CGRect clipRect = CGRectOffset(ellipse, halfMultiplier * ellipse.size.width / 2, 0);
CGContextClipToRect(contextRef, clipRect);
CGContextFillEllipseInRect(contextRef, ellipse);
CGContextRestoreGState(contextRef);

CGContextSaveGState(contextRef);
onlyDrawTopHalf = !onlyDrawTopHalf;
halfMultiplier = onlyDrawTopHalf ? -1.0 : 1.0;
ellipse = CGRectMake(0, 0, 400, 400);

clipRect = CGRectOffset(ellipse, halfMultiplier * ellipse.size.width / 2, 0);
CGContextClipToRect(contextRef, clipRect);
CGContextFillEllipseInRect(contextRef, ellipse);
CGContextRestoreGState(contextRef);

UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
NSData *data = (NSData *)CGDataProviderCopyData(CGImageGetDataProvider(image.CGImage));
//must free pixels
free(pixels);
pixels = (Byte *)[data bytes];


CGImageRef imageRef = image.CGImage;

// create a new image from the modified pixel data
size_t width                    = CGImageGetWidth(imageRef);
size_t height                   = CGImageGetHeight(imageRef);
size_t bitsPerComponent         = CGImageGetBitsPerComponent(imageRef);
size_t bitsPerPixel             = CGImageGetBitsPerPixel(imageRef);
size_t bytesPerRow              = CGImageGetBytesPerRow(imageRef);

CGColorSpaceRef colorspace      = CGColorSpaceCreateDeviceRGB();
CGBitmapInfo bitmapInfo         = CGImageGetBitmapInfo(imageRef);
CGDataProviderRef provider      = CGDataProviderCreateWithData(NULL, pixels, [data length], NULL);

CGImageRef newImageRef = CGImageCreate (
                                        width,
                                        height,
                                        bitsPerComponent,
                                        bitsPerPixel,
                                        bytesPerRow,
                                        colorspace,
                                        bitmapInfo,
                                        provider,
                                        NULL,
                                        false,
                                        kCGRenderingIntentDefault
                                        );
// the modified image
UIImage *newImage   = [UIImage imageWithCGImage:newImageRef];
sublayer2.contents = (id)[newImage CGImage];
[self.view.layer addSublayer:sublayer2];
// cleanup
[data release];
CGColorSpaceRelease(colorspace);
CGDataProviderRelease(provider);
CGImageRelease(newImageRef);

我已经添加了[数据发布]，但似乎仍有一些泄漏。

编辑 - 我发现除了 [数据发布] 我还需要通过调用来关闭我的图像上下文 UIGraphicsEndImageContext(); 泄漏已经停止。

Answer 1

NSData *data = (NSData *)CGDataProviderCopyData(CGImageGetDataProvider(image.CGImage));

数据对象未释放。您有时会使用自动释放图像对象，它可能会导致内存警告。

UIImage *newImage   = [UIImage imageWithCGImage:newImageRef];

最好手动创建对象，然后在完成对象后释放。因为我们永远不知道 autorelase 池何时会耗尽。