iphone - 如果文件已经存在并且您尝试写入它会发生什么？

Question

它会被覆盖还是会写入失败？

NSData * pdfData = [[NSData alloc] initWithData:[PDFImageConverter convertImageToPDF: [image image]]];
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString * filename = sharedManager.localFileName; //file name already exists
    NSString *pdfPath = [documentsDirectory stringByAppendingPathComponent:filename];
    [pdfData writeToFile:pdfPath atomically:YES];
    [pdfData release];

Answer 1

写入成功会被覆盖。注意如果atomically设置为YES，写入失败不会损坏原文件。如果 atomically 设置为 NO，它会。