NSFileWrapper Class Reference

Discussion

Use this method to add an existing file wrapper as a child of a directory file wrapper. If the file wrapper does not have a preferred filename, use the setPreferredFilename: method to give it one before calling addFileWrapper:. To create a new file wrapper and add it to a directory, use the addRegularFileWithContents:preferredFilename: method.

Discussion

This is a convenience method. The default implementation allocates a new file wrapper, initializes it with initRegularFileWithContents:, sends it setPreferredFilename:, adds it to the directory with addFileWrapper:, and returns what addFileWrapper: returned.

Discussion

The filename is used for record-keeping purposes only and is set automatically when the file wrapper is created from the file system using initWithURL:options:error: and when it’s saved to the file system using writeToURL:options:originalContentsURL:error: (although this method allows you to request that the filename not be updated).

The filename is usually the same as the preferred filename, but might instead be a name derived from the preferred filename. You can use this method to get the name of a child that's just been read. Don’t use this method to get the name of a child that's about to be written, because the name might be about to change; send keyForFileWrapper: to the parent instead.

Discussion

Returns a dictionary whose values are the file wrapper's children and whose keys are the unique filenames that have been assigned to each one. This method may return nil if the user modifies the directory after you call readFromURL:options:error: or initWithURL:options:error: but before NSFileWrapper has read the contents of the directory. Use the NSFileWrapperReadingImmediate reading option to reduce the likelihood of that problem.

Discussion

After initialization, the file wrapper is not associated with a file-system node until you save it using writeToURL:options:originalContentsURL:error:.

The receiver is initialized with open permissions: anyone can read, write, or modify the directory on disk.

If any file wrapper in the directory doesn’t have a preferred filename, its preferred name is automatically set to its corresponding key in the childrenByPreferredName dictionary.

Discussion

After initialization, the file wrapper is not associated with a file-system node until you save it using writeToURL:options:originalContentsURL:error:.

The file wrapper is initialized with open permissions: anyone can write to or read the file wrapper.

Discussion

The file wrapper is not associated with a file-system node until you save it using writeToURL:options:originalContentsURL:error:.

The file wrapper is initialized with open permissions: anyone can modify or read the file reference. .

Discussion

The file wrapper is not associated with a file-system node until you save it using writeToURL:options:originalContentsURL:error:.

Discussion

If url is a directory, this method recursively creates file wrappers for each node within that directory. Use the fileWrappers method to get the file wrappers of the nodes contained by the directory.

Discussion

Invocations of readFromURL:options:error: may change what is returned by subsequent invocations of this method if the type of the file on disk has changed.

Discussion

Invocations of readFromURL:options:error: may change what is returned by subsequent invocations of this method if the type of the file on disk has changed.

Discussion

Invocations of readFromURL:options:error: may change what is returned by subsequent invocations of this method if the type of the file on disk has changed.

Discussion

The contents of files are not compared; matching of regular files is based on file modification dates. For a directory, children are compared against the files in the directory, recursively.

Because children of directory file wrappers are not read immediately by the initWithURL:options:error: method unless the NSFileWrapperReadingImmediate reading option is used, even a newly-created directory file wrapper might not have the same contents as the directory on disk. You can use this method to determine whether the file wrapper's contents in memory need to be updated.

If the file wrapper needs updating, use the readFromURL:options:error: method with the NSFileWrapperReadingImmediate reading option.

This table describes which attributes of the file wrapper and file-system node are compared to determine whether the file wrapper matches the node on disk:

Discussion

This name is normally used as the dictionary key when a child file wrapper is added to a directory file wrapper. However, if another file wrapper with the same preferred name already exists in the directory file wrapper when the receiver is added, the filename assigned as the dictionary key may differ from the preferred filename.

Discussion

When reading a directory, children are added and removed as necessary to match the file system.

Discussion

This method may return nil if the user modifies the file after you call readFromURL:options:error: or initWithURL:options:error: but before NSFileWrapper has read the contents of the file. Use the NSFileWrapperReadingImmediate reading option to reduce the likelihood of that problem.

Discussion

Returns an NSData object suitable for passing to initWithSerializedRepresentation:. This method may return nil if the user modifies the contents of the file-system node after you call readFromURL:options:error: or initWithURL:options:error: but before NSFileWrapper has read the contents of the file. Use the NSFileWrapperReadingImmediate reading option to reduce the likelihood of that problem.

Discussion

The file name is a dictionary key used to store fileWrapper in a directory’s list of child file wrappers. The dictionary key is a unique filename, which is the same as the child file wrapper's preferred filename unless that name is already in use as a key in the directory’s dictionary of children. See “Working with Directory Wrappers” in File System Programming Guide for more information about the file-wrapper list structure. In general, the filename is set for you by the initWithURL:options:error:, initDirectoryWithFileWrappers:, or writeToURL:options:originalContentsURL:error: methods; you do not normally have to call this method directly.

Discussion

When a file wrapper is added to a parent directory file wrapper, the parent attempts to use the child’s preferred filename as the key in its dictionary of children. If that key is already in use, then the parent derives a unique filename from the preferred filename and uses that for the key.

When you change the preferred filename of a file wrapper, the default implementation of this method causes existing parent directory file wrappers to remove and re-add the child to accommodate the change. Preferred filenames of children are not preserved when you write a file wrapper to disk and then later instantiate another file wrapper by reading the file from disk. If you need to preserve the user-visible names of attachments, you have to store the names yourself.

Discussion

This method may return nil if the user modifies the symbolic link after you call readFromURL:options:error: or initWithURL:options:error: but before NSFileWrapper has read the contents of the link. Use the NSFileWrapperReadingImmediate reading option to reduce the likelihood of that problem.