CGPDF iPhone / iPad内存问题 [英] CGPDF iPhone/iPad memory problems
问题描述
我一直在努力为iPhone / iPad制作一个可用的PDF阅读器，但事情并不止于此。似乎用CGContextDrawPDFPage绘制的所有页面都在内部缓存，从未发布过。
I've been struggling for ages trying to make a working PDF reader for iPhone/iPad, but the thing just won't stop eating memory. It seems that all the pages drawn with CGContextDrawPDFPage are cached internally and never released.
我不是唯一遇到此问题的人： http://lists.apple.com/archives/quartz-dev/2010/Apr/msg00025.html
I'm not the only one with this problem: http://lists.apple.com/archives/quartz-dev/2010/Apr/msg00025.html
http://web.archiveorange.com/archive/v/SEb6acvPicMB2NdIjEd3
第一个帖子的一个回复：
One response from the first thread:
如果这是我认为的话是，它不是泄漏而是缓存。不是在调用之间保留PDF文档，而是尝试创建文档，获取和绘制页面，然后在完成后释放文档。
If this is what I think it is, it isn't a leak but rather a cache. Instead of retaining the PDF document between calls, try creating the document, getting and drawing the page, then releasing the document when your done.
我试过了，它解决了这个问题，但它太慢了。虽然以正常的方式进行（即没有为每次抽奖加载/发布CGPDFDocument），但是在我到达文档的第4页或第5页并且崩溃之前，工作良好且合理地快。
I've tried it, and it solves the problem, but it's too damn slow. Whereas doing it in the "normal" way (i.e. without loading/releasing CGPDFDocument for every draw) works good and reasonably fast until I reach the 4th or 5th page of the document and it crashes.
我已经搜索了这个问题多年了：每个人都有同样的问题，但显然没有人得到它的工作。我发现的唯一样本加载了一页PDF，所以显然一切都正常，直到您加载一个包含多个页面的文档（当然，如果事物中有图像，它甚至更早崩溃）。这真让我抓狂。
I've googled this problem for ages: everybody has the same problem but apparently nobody got it working. The only samples I found load a one-page PDF, so obviously everything works fine until you load a document with multiple pages (and of course if the thing has images in it, it crashes even earlier). This is driving me crazy.
所以问题是：你在应用程序中如何使用CGPDF处理PDF绘图？任何帮助将不胜感激。谢谢。
So the question is: how exactly do you handle PDF drawing with CGPDF in your app? Any help would be greatly appreciated. Thanks.
推荐答案
我目前的企业项目基于PDF阅读器。我没有发布CGPDFDocument，我可以翻阅14页apple pdf，应用程序最大值为30mb。我不能给你代码，但我可以指出你正确的方向。
My current Enterprise Project is based round a PDF reader. I don't release CGPDFDocument and I can page through a 14 page apple pdf with the app maxing at 30mb. I cant give you code but i can point you in the right direction.
我在这里开始了一个类似的线程：用于iPhone / iPad / iOs的快速和精益PDF阅读器 - 提示和提示？
I started a similar thread here: Fast and Lean PDF Viewer for iPhone / iPad / iOs - tips and hints?
一些提示：
- 尽可能将任何媒体保存到磁盘。
-Save any media to disk when you can.
- 如果在TiledLayers上渲染，则使用更大的tileSizes
-Use larger tileSizes if rendering on TiledLayers
- 表示图像渲染速度比CGPDFPageRef快
-Note that images will render faster than a CGPDFPageRef
- 使用NSOperations提前准备页面
时间。
-Use NSOperations to prepare pages ahead
of time.
- 回收页面对象
- 在您不需要时立即关闭任何打开的上下文
-Close any open Contexts as soon as you don't need them
- 收到内存警告发布并重新加载DocRef
-on receiving a memory warnings release and reload the DocRef
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