如何在使用timeIntervalSince1970進行轉換時將fileCreationDate精確到6位小數？

Question

轉換爲NSTimeInverval時，如何將NSDocumentsDirectory中存儲的文件的fileCreationDate轉換爲小數點後6位的精度？

某些代碼：

//Not accurate enough: 
NSDictionary* fileAttribs = [[NSFileManager defaultManager] attributesOfItemAtPath:myPhotoPath error:nil]; 
NSDate *creationDateOfPhoto = [fileAttribs fileCreationDate]; 
NSTimeInterval creationDateAsTimeInterval = [creationDateOfPhoto timeIntervalSince1970]; 
NSLog(@"Creation Date of Photo As Time Interval Since 1970: %f", creationDateAsTimeInterval); 

//With the desired accuracy: 
NSDate* now = [NSDate date]; 
NSTimeInterval nowStampAsTimeInterval = [now timeIntervalSince1970]; 
NSLog(@"Now As Time Interval Since 1970: %f", nowStampAsTimeInterval); 

從該碼A輸出樣本是：

Creation Date of Photo As Time Interval Since 1970: 1373022866.000000 
Now As Time Interval Since 1970:     1373022884.294028 

是否有可能或者是存儲在NSDocuments的限制？

Answer 1

這是一個操作系統級別的限制。 HFS+，iOS使用的文件系統的日期分辨率爲1秒 - 這就是爲什麼您的所有文件時間戳都是整秒。 Sub second精度不受支持。抱歉!