objective-c - 如何正确释放一个CF对象对象？

Question

我有这个方法(别人写的!)

- (CGPDFDocumentRef)getPdf {
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

    NSString *documentsDirectory = [paths objectAtIndex:0];

    NSString *pdfPath = [documentsDirectory stringByAppendingPathComponent:@"myLocalFileName.pdf"];

    NSURL *pdfURL = [NSURL fileURLWithPath:pdfPath];

    CGPDFDocumentRef pdf = CGPDFDocumentCreateWithURL((CFURLRef)pdfURL);

    return pdf;
}

现在，我运行了 Analyze 并收到了三个内存泄漏警告:

Call to function 'CGPDFDocumentCreateWithURL' returns a Core Foundation object with a +1 retain count
Object returned to caller as an owning reference (single retain count transferred to caller)
Object leaked: object allocated and stored into 'pdf' is returned from a method whose name ('getPdf') does not start with 'copy', 'mutableCopy', 'alloc' or 'new'.  This violates the naming convention rules given in the Memory Management Guide for Cocoa

有人可以告诉我这里需要/应该做什么吗？我知道我应该在 CF 函数名称中使用 create 或 copy CFRelease 一切。我不明白的是我如何发布 pdf 并且仍然能够在函数结束时返回它。我错过了什么？谢谢。

Answer 1

您需要像此处所示的 clang 源注释 http://cocoasamurai.blogspot.com/2012/01/clang-source-annotations.html

    #import <AppKit/AppKit.h>
@interface NSColor (CWNSColorAdditions)
-(CGColorRef)cw_cgColor CF_RETURNS_RETAINED;
@end