在目录中获取文件（及其属性） [英] Getting files (and its attributes) in a directory

问题描述

我想得到一个目录中的文件列表，但我需要知道，如果该文件是一个目录，当它被最后一次修改，和offcourse它的名称:)。所以我尝试这样：

  NSFileManager * fm = [NSFileManager defaultManager]; 
 NSURL * directoryURL = [NSURL fileURLWithPath：@/ Users / nacho4d / Desktop /]; 
 NSArray * urls = [fm contentOfDirectoryAtURL：directoryURL 
 includePropertiesForKeys：[NSArray arrayWithObjects：NSURLNameKey，NSURLIsDirectoryKey，NSURLContentModificationDateKey，nil] 
 options：NSDirectoryEnumerationSkipsHiddenFiles 
 error：nil]; 
 NSError * error = nil; 
 NSString * name; 
 NSDate * modificationDate; 
 NSNumber * isDirectory; 
 for（NSURL * url in urls）{
 if（！[url getResourceValue：& name forKey：NSURLNameKey error：& error]）{
 NSLog（@name：％@ ，[error localizedDescription]）; error = nil; 
} 
 if（！[url getResourceValue：& modificationDate forKey：NSURLContentModificationDateKey error：& error]）{
 NSLog（@modificationDate：％@，[error localizedDescription]）; error = nil; 
} 
 if（！[url getResourceValue：& isDirectory forKey：NSURLIsDirectoryKey error：& error]）{
 NSLog（@isDirectory：％@，[error localizedDescription]）; error = nil; 
} 
 NSLog（@％@％@％@，name，modificationDate，isDirectory）;但是我总是得到（null）（null）$ {
} 
  



< （null），没有错误，但没有数据;（

我不知道这里有什么问题？

PS：我知道 contentsOfDirectoryAtPath：error：和 attributesOfItemAtPath：error：是不是最好的方法，是吗？
我计划在可以包含大量文件的文件夹中使用它，所以我想这是最有效的方式。

编辑iOS5及更高版本

如@jeremyP指向，根据文档，方法未实现在iOS4中，但自iOS5及更高版本后，它似乎可以正常运行：

可用性

在iOS 5.0和更高版本中可用。（符号在iOS 4中存在，但不执行任何操作。）

是我最新的想法。现在在iOS 5
和6一切正常工作：）

解决方案

这不是你的问题的答案但是你的错误检查应该看起来像这样：

  if（！[url getResourceValue：& name forKey：NSURLNameKey error：&错误]）
 {
 NSLog（@name：％@，[error localizedDescription]）; error = nil; 
} 
  

编辑

无法找出问题所在，只是重新阅读方法的文档。重要的句子是正在讨论的一句话：

此方法在iOS中未实现，因此不执行任何操作。

I want to get a list of files within a directory but I need to know if the file is a directory, when it was last modified, and offcourse its name :) . So I tried this:

NSFileManager *fm = [NSFileManager defaultManager];
NSURL *directoryURL = [NSURL fileURLWithPath:@"/Users/nacho4d/Desktop/"];
NSArray *urls = [fm contentsOfDirectoryAtURL:directoryURL 
                      includingPropertiesForKeys:[NSArray arrayWithObjects:NSURLNameKey, NSURLIsDirectoryKey, NSURLContentModificationDateKey, nil] 
                                         options:NSDirectoryEnumerationSkipsHiddenFiles 
                                           error:nil];
NSError *error = nil;
NSString *name;
NSDate *modificationDate;
NSNumber *isDirectory;
for (NSURL *url in urls) {
    if (![url getResourceValue:&name forKey:NSURLNameKey error:&error]) {
        NSLog(@"name: %@", [error localizedDescription]);error = nil;
    }
    if (![url getResourceValue:&modificationDate forKey:NSURLContentModificationDateKey error:&error]) {
        NSLog(@"modificationDate: %@", [error localizedDescription]); error = nil;
    }
    if (![url getResourceValue:&isDirectory forKey:NSURLIsDirectoryKey error:&error]) {
        NSLog(@"isDirectory: %@", [error localizedDescription]); error = nil;
    }
    NSLog(@"%@ %@ %@", name, modificationDate, isDirectory);
}

However I always get (null) (null) (null), no errors but no data ;(

I wonder what is wrong here?

PS: I am aware of contentsOfDirectoryAtPath:error: and attributesOfItemAtPath:error: but I think that is not the best way of doing this, is it? I plan to use this in folders that can contain a large number of files so I would like to do this the most efficient way possible.

Edit for iOS5 and later

As @jeremyP pointed, According to the docs the method is unimplemented in iOS4 but since iOS5 and later it seems to work properly:

Availability
Available in iOS 5.0 and later. (Symbol is present in iOS 4, but performs no operation.)

This question was done when iOS4 was the latest I think. Now in iOS 5 and 6 Everything works as expected :)

解决方案

This isn't the answer to your question but your error checking should look like this:

if (![url getResourceValue:&name forKey:NSURLNameKey error:&error])
{
    NSLog(@"name: %@", [error localizedDescription]);error = nil;
}

Edit

Couldn't figure out what the problem was, but have just reread the documentation on the method. The important sentence is the one under discussion that says:

This method is unimplemented in iOS, so it performs no operation.

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