Nsfilemanager operations in IOS [Z]

1. File Creation

 

-(Ibaction) createfile { // For error messages Nserror * error; // Create a file manager Nsfilemanager * filemgr = [nsfilemanager defaultmanager]; // Point to the file directory Nsstring * documentsdirectory = [nshomedirectory () stringbyappendingpathcomponent: @ "documents"]; // Create a directory [[Nsfilemanager defaultmanager] createdirectoryatpath: [nsstring stringwithformat: @ "% @/myfolder", nshomedirectory ()] attributes: Nil]; // File we want to create in the specified ents directory the file we want to create will appear in the file directory // Result is:/Documents documents/file1.txt. The result is/documents/file1.txt. Nsstring * filepath = [documentsdirectory Stringbyappendingpathcomponent: @ "file2.txt"]; // String to be written Nsstring * STR = @ "iphonedeveloper tips \ nhttp: // iphonedeveloptips, com "; // Write a file [STR writetofile: filepath atomically: Yes encoding: nsutf8stringencoding error: & error]; // Display the contents of the file directory Nslog (@ "documentsdirectory: contentsofdirectoryatpath: documentsdirectory error: & error]); }

 

 

2. Rename the file

 

Rename a file To rename an object, we need to move the object to a new path. The following code creates the desired path of the target file, and then requests to move the file and display the file directory after moving it. // Rename the object by moving the object Nsstring * filepath2 = [documentsdirectory Stringbyappendingpathcomponent: @ "file2.txt"]; // Determine whether to move If ([filemgr moveitematpath: filepath topath: filepath2 error: & error]! = Yes) Nslog (@ "unable to move file: % @", [error localizeddescription]); // Display the contents of the file directory Nslog (@ "documentsdirectory: % @", [Filemgr contentsofdirectoryatpath: documentsdirectoryerror: & error]);

 

 

3. delete an object

 

To complete this technique, let's take a look at how to delete an object: // Determine whether to delete the file in filepath2 If ([filemgr removeitematpath: filepath2 error: & error]! = Yes) Nslog (@ "unable to delete file: % @", [error localizeddescription]); // Display the contents of the file directory Nslog (@ "documentsdirectory: % @", [Filemgr contentsofdirectoryatpath: documentsdirectoryerror: & error]); Once the file is deleted, as you expected, the file directory will be automatically cleared: These examples can only show you some details about file processing. To get a more comprehensive and detailed explanation, you need to understand the nsfilemanager file.

 

 

4. Delete all files in the directory

 

// Obtain the file path -(Nsstring *) attchmentfolder { Nsstring * Document = [nssearchpathfordirectoriesindomains (nsdocumentdirectory, nsuserdomainmask, yes) objectatindex: 0]; Nsstring * Path = [document stringbyappendingpathcomponent: @ "attchments"]; Nsfilemanager * manager = [nsfilemanager defamanager manager]; If (! [Manager contentsofdirectoryatpath: path error: Nil]) { [Manager createdirectoryatpath: path withintermediatedirectories: No attributes: Nil error: Nil]; } Return path; }   -- Clear attachments Bool result = [[nsfilemanager defaultmanager] removeitematpath: [[mopappdelegate instance] attchmentfolder] error: Nil];

How to obtain the attributes of a file on the iPhone

-(Nsdata *) applicationdatafromfile :( nsstring *) filename

{

Nsarray * paths = nssearchpathfordirectoriesindomains (nsdocumentdirectory, nsuserdomainmask, yes );

Nsstring * documentsdirectory = [paths objectatindex: 0];

Nsstring * appfile = [documentsdirectory stringbyappendingpathcomponent: Filename];

Nsdata * Data = [[nsdata alloc] initwithcontentsoffile: appfile] autorelease];

Return data;

}

-(Void) getfileattributes

{

Nsfilemanager * filemanager = [nsfilemanager defaultmanager];

Nsstring * Path = @ "/1ct. rtf ";

Nsdictionary * fileattributes = [filemanager fileattributesatpath: path traverselink: Yes];

Nslog (@"@@");

If (fileattributes! = Nil ){

Nsnumber * filesize;

Nsstring * fileowner, * creationdate;

Nsdate * filemoddate;

// Nsstring * nsfilecreationdate

// File Size

If (filesize = [fileattributes objectforkey: nsfilesize]) {

Nslog (@ "file size: % Qi \ n", [filesize unsignedlonglongvalue]);

}

// File creation date

If (creationdate = [fileattributes objectforkey: nsfilecreationdate]) {

Nslog (@ "file creationdate: % @ \ n", creationdate );

// Textfield. Text = nsfilecreationdate;

}

// File owner

If (fileowner = [fileattributes objectforkey: nsfileowneraccountname]) {

Nslog (@ "Owner: % @ \ n", fileowner );

}

// File modification date

If (filemoddate = [fileattributes objectforkey: nsfilemodificationdate]) {

Nslog (@ "modification date: % @ \ n", filemoddate );

}

}

Else {

Nslog (@ "path (% @) is invalid.", PATH );

}

}

 

 

///////////////////

File type. What about file thumbnails ???

 

======================================

// Obtain the Home Directory of the current application
Nsstring directorypath = nshomedirectory ();

// Obtain all files in the current directory
Nsarray directorycontents = [[nsfilemanager defaultmanager] directorycontentsatpath: directorypath];

 

// Obtain a file or folder
Nsstring * selectedfile = (nsstring *) [directorycontents objectatindex: indexpath. Row];

// Construct a complete path
[Directorypath stringbyappendingpathcomponent: selectedfile];

 

 

Bool isdir;

// Determine whether it is a directory

If ([[nsfilemanager defaultmanager] fileexistsatpath: selectedpath isdirectory: & isdir] & isdir)

{// Directory

}

Else

{// File

}

 

 

 

 

// Format the date
Nsdateformatter * dateformatter = [[nsdateformatter alloc] init];

[Dateformatter setdatestyle: nsdateformattermediumstyle];

[Dateformatter settimestyle: nsdateformatternostyle];

// Format the number

Nsnumberformatter * numberformatter = [[nsnumberformatter alloc] init];

[Numberformatter setpositiveformat: @ "#,## 0. ## bytes"];

 

 

// Get file attributes

Nsdictionary * fileattributes = [[nsfilemanager defaultmanager] fileattributesatpath: directorypath traverselink: Yes];

// Obtain the file creation date

Nsdate * modificationdate = (nsdate *) [fileattributes objectforkey: nsfilemodificationdate];

// Obtain the object size in bytes

Nsnumber * filesize = (nsnumber *) [fileattributes objectforkey: nsfilesize];
// Format the file size
Nsstring A = [numberformatter stringfromnumber: filesize];

// Format the file creation date

Nsstring B = [dateformatter stringfromdate: modificationdate];

 

[Numberformatter release];

[Dateformatter release];

 

// Read File Content operation-(void) loadfilecontentsintotextview

{

 

 

// Open a file through a stream

 

Nsinputstream * inputstream = [[nsinputstream alloc] initwithfileatpath: filepath];

 

[Inputstream open];

 

Nsinteger maxlength = 128;

Uint8_t readbuffer [maxlength];

// Whether the end ID has been reached

Bool endofstreamreached = no;

// Note: this tight loop will block until stream ends

While (! Endofstreamreached)

{

Nsinteger bytesread = [inputstream read: readbuffer maxlength: maxlength];

If (bytesread = 0)

{// Read the file to the end

Endofstreamreached = yes;

}

Else if (bytesread =-1)

{// File reading error

Endofstreamreached = yes;

}

Else

{

Nsstring * readbufferstring = [[nsstring alloc] initwithbytesnocopy: readbuffer length: bytesread encoding: nsutf8stringencoding freewhendone: No];

// Load non-segmented characters to the view

[Self appendtexttoview: readbufferstring];

[Readbufferstring release];

}

}

[Inputstream close];

[Inputstream release];

}

 

 

 

 

Asynchronous file reading in the network, network reliability may cause blocking of the above method

Nsstream can work asynchronously. You can register a function that calls back when there are bytes in the stream. If there is no readable, do not block it.