我们正在尝试让用户从他们的相册中导入图片(UIImagePickerController)，并且我们正在缩放/调整大于 8 兆像素(iPhone 标准)的图像。

但每次应用程序崩溃时，与 assetsd 的连接中断或 assetsd 死亡 和 Received memory warning 在导入图片之后或之前发出警告。有时 Received memory warning 仍在UIImagePickerController中寻找要导入的图片时弹出警告。

特别是在 iPhone 4S 上，情况更糟，请帮助我们优化我们的代码，使其在 iPhone 4S 或 iPad 2 等旧设备上运行时没有警告和崩溃。

如果我们在使用 CoreGraphics 缩小/调整图像大小时做错了什么，请告诉我们。(因为这是使用大量内存的地方)。

 - (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
    {
        UIImage *selectedImage=[info objectForKey:UIImagePickerControllerOriginalImage];
        if(UI_USER_INTERFACE_IDIOM()==UIUserInterfaceIdiomPhone)
        {
            [picker dismissViewControllerAnimated:YES completion:nil];
        }
        else
        {
            [popoverController dismissPopoverAnimated:YES];
            [self popoverControllerDidDismissPopover:popoverController];
        }

        // COMPRESSING IMAGE
        NSData   *selectedImageData=UIImageJPEGRepresentation(selectedImage, 0.1);
        UIImage *selectedImageFromData=[UIImage imageWithData:selectedImageData];

        // IMAGE ASPECT RATIO
        CGFloat originalWidth=selectedImageFromData.size.width;
        CGFloat originalHeight=selectedImageFromData.size.height;
        CGFloat myWidth=2048;
        CGFloat myHeight=2048;
        CGFloat widthRatio=myWidth/originalWidth;
        CGFloat heightRatio=myHeight/originalHeight;
        CGFloat dynamicWidth=heightRatio*originalWidth;
        CGFloat dynamicHeight=widthRatio*originalHeight;


        //SCALING UIIMAGE MORE THAN 8 MEGAPIXELS
        if (((selectedImageFromData.size.width>3264) && (selectedImageFromData.size.height>2448)) || ((selectedImageFromData.size.height>3264) && (selectedImageFromData.size.width>2448)))
        {



             // DATA FROM UIIMAGE TO CORE GRAPHICS
             CGImageRef CoreGraphicsImage=selectedImageFromData.CGImage;
            CGColorSpaceRef colorSpace = CGImageGetColorSpace(CoreGraphicsImage);
            CGBitmapInfo bitmapInfo=CGImageGetBitmapInfo(CoreGraphicsImage);
            CGImageGetBitsPerComponent(CoreGraphicsImage);


            // RESIZING WIDTH OF THE IMAGE
            if (originalWidth>originalHeight)
            {


            CGContextRef context=CGBitmapContextCreate(NULL, myWidth, dynamicHeight, CGImageGetBitsPerComponent(CoreGraphicsImage), CGImageGetBytesPerRow(CoreGraphicsImage), colorSpace, bitmapInfo);


            CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
            CGContextDrawImage(context, CGRectMake(0, 0, myWidth, dynamicHeight), CoreGraphicsImage);
            CGImageRef CGscaledImage=CGBitmapContextCreateImage(context);
                UIImage *CGLastimage = [UIImage imageWithCGImage: CGscaledImage];
                NSLog(@"%f",CGLastimage.size.width);
                NSLog(@"%f",CGLastimage.size.height);

                VisualEffectImageVIew.image=CGLastimage;
                BackgroundImageView.image=CGLastimage;
                ForegroundImageView.image=CGLastimage;
            }


            //RESIZING HEIGHT OF THE IMAGE
            if (originalHeight>originalWidth)
            {
                CGContextRef context=CGBitmapContextCreate(NULL, dynamicWidth, myHeight, CGImageGetBitsPerComponent(CoreGraphicsImage), CGImageGetBytesPerRow(CoreGraphicsImage), colorSpace, bitmapInfo);


                CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
                CGContextDrawImage(context, CGRectMake(0, 0, dynamicWidth, myHeight), CoreGraphicsImage);
                CGImageRef CGscaledImage=CGBitmapContextCreateImage(context);
                UIImage *CGLastimage = [UIImage imageWithCGImage: CGscaledImage];

                NSLog(@"%f",CGLastimage.size.width);
                NSLog(@"%f",CGLastimage.size.height);

                VisualEffectImageVIew.image=CGLastimage;
                BackgroundImageView.image=CGLastimage;
                ForegroundImageView.image=CGLastimage;

            }


        }
        else
        {
            NSLog(@" HEIGHT %f",selectedImageFromData.size.height);
            NSLog(@" WIDTH %f",selectedImageFromData.size.width);

        VisualEffectImageVIew.image=selectedImageFromData;
        BackgroundImageView.image=selectedImageFromData;
        ForegroundImageView.image=selectedImageFromData;
        }


    }

内存报告

在 UIImagePickerController 中滚动时

http://i.stack.imgur.com/qxx62.png

缩放/调整 UIImage 大小时

http://i.stack.imgur.com/ELCA6.png

最佳答案

两点。

首先，您没有释放您创建的对象——您正在泄漏大量内存。无论您是否使用 ARC，都必须为每个 CGCreate 调用适本地调用 CGContextRelease 或 CGImageRelease。

其次，如果您只想调整大小，使用 coregraphics 就太过分了，请改用 UIKit。在我下面使用的代码中，请注意 @autorelease 的使用，以确保一旦上下文结束，ARC 就会清除对象

- (UIImage *)fitImage:(UIImage *)image scaledToFillSize:(CGSize)size {
    // do not upscale

    @autoreleasepool {
        if( image.size.width <= size.width && image.size.height <= size.height )
            return image;

        CGFloat scale = MIN(size.width/image.size.width, size.height/image.size.height);
        CGFloat width = image.size.width * scale;
        CGFloat height = image.size.height * scale;

        CGRect imageRect;
        // center image
        if( scale != 1.0 ) { // avoid divide by zero?
            if( size.width/image.size.width < size.height/image.size.height ) {
                // height needs to be centered
                imageRect = CGRectMake(0, (size.height-height)/2, width, height);
            } else {
                // width needs to be centered
                imageRect = CGRectMake((size.width-width)/2, 0, width, height);
            }
        }

        UIGraphicsBeginImageContextWithOptions(size, YES, 0);
        [[UIColor CollageBorderUIColor] setFill]; // otherwise it's ugly black fill
        UIRectFill(CGRectMake(0, 0, size.width, size.height));
        [image drawInRect:imageRect];
        UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
        return newImage;
    }
}

关于ios - 与 assetsd 的连接中断或 assetsd 死亡(带有内存警告)，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/30137378/