Question

我正在开发iOS应用。我需要裁剪从PDF生成的图像。有时，图像分辨率可能非常大我使用跟随代码生成裁剪图像。我的问题是内存一直在增加。从未发布。

- (UIImage *)croppedImageWithFrame:(CGRect)frame angle:(NSInteger)angle{
UIImage *croppedImage = nil;
CGPoint drawPoint = CGPointZero;

UIGraphicsBeginImageContextWithOptions(frame.size, YES, self.scale);
{
    CGContextRef context = UIGraphicsGetCurrentContext();

    //To conserve memory in not needing to completely re-render the image re-rotated,
    //map the image to a view and then use Core Animation to manipulate its rotation
    if (angle != 0) {
        UIImageView *imageView = [[UIImageView alloc] initWithImage:self];
        imageView.layer.minificationFilter = @"nearest";
        imageView.layer.magnificationFilter = @"neareset";
        imageView.transform = CGAffineTransformRotate(CGAffineTransformIdentity, angle * (M_PI/180.0f));
        CGRect rotatedRect = CGRectApplyAffineTransform(imageView.bounds, imageView.transform);
        UIView *containerView = [[UIView alloc] initWithFrame:(CGRect){CGPointZero, rotatedRect.size}];
        [containerView addSubview:imageView];
        imageView.center = containerView.center;
        CGContextTranslateCTM(context, -frame.origin.x, -frame.origin.y);
        [containerView.layer renderInContext:context];
    }
    else {
        CGContextTranslateCTM(context, -frame.origin.x, -frame.origin.y);
        [self drawAtPoint:drawPoint];
    }

    croppedImage = UIGraphicsGetImageFromCurrentImageContext();
}
UIGraphicsEndImageContext();

return croppedImage;

}

当我调试时，它在线燃烧100MB

UIGraphicsBeginImageContextWithOptions(frame.size, YES, self.scale);

然后当遇到跟进线时，再烧掉150MB

[self drawAtPoint:drawPoint];

当运行到跟随行时，它会释放100MB

UIGraphicsEndImageContext();

完成后，150MB从未发布

我认为UIGraphicsEndImageContext（）应该释放所有250MB。为什么不呢？

drawAtPoint正在吃记忆

0 个答案: