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我在使用 Core Graphics 库创建 PDF 文件时遇到了一个奇怪的问题。

使用CGContextEndPage方法仅在 iOS 5.1 及更高版本上会发生崩溃 (EXC_BAD_ACCESS)，在真实 iPhone 上进行测试。这不会在模拟器上发生。

我可能做错了什么？

更新

PDF方法有300多行。每次创建新页面时，我都会使用 CGContextBeginPage (pdfContext, &pageRect)。奇怪的是，在模拟器上测试时，没有崩溃。

更新 2 

// This code block sets up our PDF Context so that we can draw to it

CGContextRef pdfContext;

CFStringRef path;

CFURLRef url;

CFMutableDictionaryRef myDictionary = NULL;

// Create a CFString from the filename we provide to this method when we call it

path = CFStringCreateWithCString (NULL, filename, kCFStringEncodingUTF8);

// Create a CFURL using the CFString we just defined

url = CFURLCreateWithFileSystemPath (NULL, path, kCFURLPOSIXPathStyle, 0);

CFRelease (path);

// This dictionary contains extra options mostly for 'signing' the PDF

myDictionary = CFDictionaryCreateMutable(NULL, 0, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);

CFDictionarySetValue(myDictionary, kCGPDFContextTitle, title);

CFDictionarySetValue(myDictionary, kCGPDFContextCreator, CFSTR("MindScore"));

// Create our PDF Context with the CFURL, the CGRect we provide, and the above defined dictionary

pdfContext = CGPDFContextCreateWithURL (url, &pageRect, myDictionary);

// Cleanup our mess

CFRelease(myDictionary);

CFRelease(url);

for (…) {

/** START NEW PAGE */

    if (…) {

    CGContextEndPage (pdfContext);

    }

    /** START INITIALIZATION OF PAGE*/

    if (…) {

       CGContextBeginPage (pdfContext, &pageRect); 

       // This code block will create an image that we then draw to the page

       const char *picture = "pdf-sheet";

       CGImageRef image;

       CGDataProviderRef provider;

       CFStringRef picturePath;

       CFURLRef pictureURL; 

       picturePath = CFStringCreateWithCString (NULL, picture,

        kCFStringEncodingUTF8);

       pictureURL = CFBundleCopyResourceURL(CFBundleGetMainBundle(), picturePath, CFSTR("png"), NULL);

       CFRelease(picturePath);

       provider = CGDataProviderCreateWithURL (pictureURL);

       //CFRelease (pictureURL);

       image = CGImageCreateWithPNGDataProvider (provider, NULL, true, kCGRenderingIntentDefault);

       CGDataProviderRelease (provider);

       CGContextDrawImage (pdfContext, CGRectMake(0, 0, 2480, 3508),image);

       CGImageRelease (image);

       // End image code

    }
}

[...]

/** END LAST PAGE */

NSLog(@"END LAST PAGE");

CGContextEndPage (pdfContext);

CGContextRelease (pdfContext);
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