CGPDFDocumentCreateWithURL失败（NSURL与CFURLRef的免费桥接） [英] CGPDFDocumentCreateWithURL fails (Toll-Free bridging of NSURL to CFURLRef)

问题描述

我有以下功能：

- (void)loadPdfFromPath:(NSString*)path
{   
    NSURL *pathUrl = [NSURL URLWithString:path];

    _pdfDocument = CGPDFDocumentCreateWithURL((CFURLRef)pathUrl);
}

我从文档中认为这是可行的，因为您可以从 NSURL * 到 CFURLRef 通过免费桥接。但是，此函数失败，并且我在日志中得到以下输出：

Which from the documentation I'm lead to believe will work because you can case from an NSURL* to a CFURLRef via Toll-Free Bridging. However, this function fails, and I get the following output in the log:

CFURLCreateDataAndPropertiesFromResource：错误代码-15。

CFURLCreateDataAndPropertiesFromResource: error code -15.

NB：-15 = kCFURLImproperArgumentsError

NB: -15 = kCFURLImproperArgumentsError

但是，如果我创建一个实际的 CFURLRef ，它就可以正常工作：

However, if I create an actual CFURLRef, it works absolutely fine:

- (void)loadPdfFromPath:(NSString*)path
{
    CGPDFDocumentRelease(_pdfDocument);

    CFStringRef cgPath = CFStringCreateWithCString(NULL, [path UTF8String], kCFStringEncodingUTF8);

    CFURLRef url = CFURLCreateWithFileSystemPath(NULL, cgPath, kCFURLPOSIXPathStyle, 0);

    _pdfDocument = CGPDFDocumentCreateWithURL(url);

    CFRelease(url);
    CFRelease(cgPath)
}

我缺少什么？我很乐意将第二个函数保留在代码中，但我想知道为什么第一个函数会失败。

What am I missing? I'm happy to keep the second function in my code, but I'd rather know why the first one is failing.

推荐答案

要将文件系统路径转换为URL，请使用

To convert a file system path to a URL, use

NSURL *pathUrl = [NSURL fileURLWithPath:path];

URLWithString 需要符合RFC 2396的URL字符串例如 http：// ...或 file：/// ...，包括方案等。

URLWithString expects a RFC 2396 conforming URL string like "http://..." or "file:///...", including the "scheme" etc.

已添加： 实际上， NSURL * pathUrl = [NSURL URLWithString：path]; 返回一个有效的对象，因此它似乎可以正常工作，但是从此URL（例如 dataWithContentsOfURL ）读取失败。

Added: Actually NSURL *pathUrl = [NSURL URLWithString:path]; returns a valid object, so it seems to work, but reading from this URL (e.g. dataWithContentsOfURL) fails.

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