在循环中释放renderInContext结果 [英] Releasing renderInContext result within a loop

问题描述

我有一个在循环中调用的方法，看起来像这样：

I have a method which is called in a loop, that looks something like this:

NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
UIImageView *background = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, PAGE_WIDTH, PAGE_HEIGHT)];
background.image = backgroundImg;

for (UIView *view in viewArray)
{
    [background addSubview:view];
}

UIGraphicsBeginImageContext(background.frame.size);
[background.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

for (UIView *view in background.subviews)
    [view removeFromSuperview];

background.image = nil;
[background release];
[image retain];
[pool drain];
[image autorelease];
return image;

然而，根据Instruments Memory Monitor的说法，内存使用量会不断上升，直到循环结束。 （它崩溃了。）

However, according to Instruments Memory Monitor, the memory usage goes up and up, and never comes down until the end of the loop. (It crashes.)

如果我将UIGraphicsBeginImageContext替换为UIGraphicsEndImageContext与

If I replace the UIGraphicsBeginImageContext to UIGraphicsEndImageContext with

UIImage * image = someotherimage;

UIImage *image = someotherimage;

然后内存不会出现峰值，但是在循环的每次迭代中都会被分配并减少，正如我所料，由于自动释放池。 （它没有崩溃）

then the memory does not spike, but is allocated and reduces on every iteration of the loop, as I would expect, due to the Autorelease pool. (It doesn't crash)

如果我只注释掉renderInContext行，它就可以了。 （不会崩溃）

And if I just comment out the renderInContext line it works fine. (Doesn't crash)

所以看起来渲染的图像似乎是以某种方式保留在图像上 - 如何让它释放它？或者任何其他建议请：）？

So it looks as if renderInContext is holding onto the image somehow - how can I get it to release it? Or any alternative suggestions please :)?

推荐答案

自然经过3天的实验，我找到了答案（答案，无论如何，我会很高兴在一小时内发表评论。

Naturally after 3 days of experimenting, I find the answer (an answer, anyway, and I would be glad of comments on this) within the hour.

我添加

background.layer.contents = nil;

UIGraphicsEndImageContext();

并且图层中的缓存内存未缓存：）。

and the cached memory in the layer is uncached :).

这篇关于在循环中释放renderInContext结果的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！