iphone - UIGraphicsContext 内存泄漏

Question

您好 在我的应用程序中，我有一个函数可以获取当前 View 的图像并将其转换为模糊图像，然后将其添加到 current.view。尽管我使用 [remove from superview] 删除了 View ，但内存仍然很高。我正在使用核心图形并将所有 UI 图像设置为零。

我收到内存泄漏警告

-(void)burImage
{
    //Get a screen capture from the current view.
    UIGraphicsBeginImageContext(CGSizeMake(320, 450));
    [self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *viewImg = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    //Blur the image
    CIImage *blurImg = [CIImage imageWithCGImage:viewImg.CGImage];

    CGAffineTransform transform = CGAffineTransformIdentity;
    CIFilter *clampFilter = [CIFilter filterWithName:@"CIAffineClamp"];
    [clampFilter setValue:blurImg forKey:@"inputImage"];
    [clampFilter setValue:[NSValue valueWithBytes:&transform objCType:@encode(CGAffineTransform)] forKey:@"inputTransform"];

    CIFilter *gaussianBlurFilter = [CIFilter filterWithName: @"CIGaussianBlur"];
    [gaussianBlurFilter setValue:clampFilter.outputImage forKey: @"inputImage"];
    [gaussianBlurFilter setValue:[NSNumber numberWithFloat:22.0f] forKey:@"inputRadius"];

    CIContext *context = [CIContext contextWithOptions:nil];
    CGImageRef cgImg = [context createCGImage:gaussianBlurFilter.outputImage fromRect:[blurImg extent]];
    UIImage *outputImg = [UIImage imageWithCGImage:cgImg];

    //Add UIImageView to current view.
    UIImageView *imgView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 320, 450)];
    [imgView setTag:1109];

    imgView.image = outputImg;
    [imgView setTag:1108];

    gaussianBlurFilter = nil;
    outputImg = nil;
    blurImg = nil;

    viewImg = nil;
    [self.view addSubview:imgView];
    UIGraphicsEndImageContext();
}

Answer 1

静态分析器(Xcode“产品”菜单上的“分析”)通知您在方法末尾缺少所需的 CGImageRelease(cgImg)。如果您有从名称中带有“Create”或“Copy”的方法/函数返回的核心基础对象，则您有责任释放它。

顺便说一下，如果你点击 图标(一次出现在页边空白处，一次出现在错误消息中出现的版本上)，它将向您显示更多信息:

这有助于追溯问题的根源，在本例中是对 createCGImage 的调用。如果您查看 documentation对于 createCGImage，它确认了这个诊断，报告:

Return Value

A Quartz 2D image. You are responsible for releasing the returned image when you no longer need it.

有关发布 Core Foundation 对象的总顾问，请参阅 Create Rule在 Core Foundation 的内存管理编程指南中。