Archive NSKeyedArchiver unarchive NSKeyedUnarchiver and file management class NSFileManager (File Operations ),

Archive NSKeyedArchiver unarchive NSKeyedUnarchiver and file management class NSFileManager (File Operations ),

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File Operations

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I. Archive NSKeyedArchiver

1. The first method is to store data.

// Archive

// Method 1

// Object -- File

NSArray * array = [[NSArray alloc] initWithObjects: @ "zhang", @ "wang", @ "li", nil];

NSString * filePath = [NSHomeDirectory () stringByAppendingPathComponent: @ "array.txt"];

BOOL success = [NSKeyedArchiver archiveRootObject: array toFile: filePath];

If (success ){

NSLog (@ "saved successfully ");

}

// Archive

NSArray * arr = [NSKeyedUnarchiver unarchiveObjectWithFile: filePath];

NSLog (@ "% @", arr );

 

2. Method 2: store parallel data (store multiple types of data ).

// Method 2:

NSArray * array = @ [@ "one", @ "two", @ "three"];

NSDictionary * dic =@{@ "key": @ "value "};

NSString * str = @ "I am a Chinese, I love China ";

// NSData data stream class

// It is used to store complex data and convert the complex data into a data stream format for convenient storage and transmission.

// For example, images and large files

// Resumable upload. The size of the fake part is 20 mb,

// Send an email: add an attachment

NSMutableData * data = [NSMutableData alloc] init];

// InitForWritingWithMutableData specifies the data stream file to be written.

NSKeyedArchiver * archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData: data];

// Encode the data. Parameter 1: The data to be encoded; parameter 2: The key and key of the encoded data.

[Archiver encodeObject: array forKey: @ "array"];

[Archiver encodeObject: dic forKey: @ "dic"];

[Archiver encodeObject: str forKey: @ "str"];

// Complete Encoding

[Archiver finishEncoding];

// Specify the file path

NSString * filePath = [NSHomeDirectory () stringByAppendingPathComponent: @ "file2"];

// Write a file

[Data writeToFile: filePath atomically: YES];

// ================================================ =

// Lower part

// Read the file in the path into the data stream first

NSMutableData * fileData = [[NSMutableData alloc] initWithContentsOfFile: filePath];

// Read the data stream file into the archive.

NSKeyedUnarchiver * unArchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData: fileData];

// Archive

NSArray * UnArray = [unArchiver decodeObjectForKey: @ "array"];

NSDictionary * UnDic = [unArchiver decodeObjectForKey: @ "dic"];

NSString * UnStr = [unArchiver decodeObjectForKey: @ "str"];

// Print

NSLog (@ "% @ \ n", UnArray, UnDic, UnStr );

 

3. Third archive method: Archive class objects

1. Implement the <NSCoding> protocol in the Class header file first.

2. recode and decode the protocol in. m.

// Re-initWithCoder Decoding Method

-(Id) initWithCoder: (NSCoder *) aDecoder

{

NSLog (@ "I am the decoding method and I am responsible for decoding ");

Self = [super init];

If (self ){

_ Name = [aDecoder decodeObjectForKey: @ "name"];

_ Phone = [aDecoder decodeObjectForKey: @ "phone"];

_ Address = [aDecoder decodeObjectForKey: @ "address"];

}

Return self;

}

 

// Re-encoding method

-(Void) encodeWithCoder: (NSCoder *) ACO

{

[Ecoder encodeObject: _ name forKey: @ "name"];

[Ecoder encodeObject: _ phone forKey: @ "phone"];

[Ecoder encodeObject: _ address forKey: @ "address"];

}

 

// [Note] forKey: A string. The encoding method and decoding method must be consistent.

 

Ii. NSFileManager file management class

 

1.1 file path

// Root path

NSString * homePath = NSHomeDirectory ();

NSLog (@ "% @", homePath );

Three directories in oc can be operated.

1. Documents // document directory

2. tmp // temporary directory: when the program exits, the contents of the temporary directory may be

3. library ---> Cache // Cache directory // under the app directory

// Obtain the Documents directory

// Write method 1

NSString * Documents = [NSHomeDirectory () stringByAppendingPathComponent: @ "Documents"];

NSLog (@ "Documents: % @", Documents );

// Statement 2

NSString * Documents1 = [NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDirectory, YES) objectAtIndex: 0];

NSLog (@ "Documents: % @", Documents1 );

// Obtain the main directory of the application

NSString * userName = NSUserName ();

NSString * rootPath = NSHomeDirectoryForUser (userName );

NSLog (@ "app root path: % @", rootPath );

// Obtain the cache directory

NSString * cachePath = [NSSearchPathForDirectoriesInDomains (NSCachesDirectory, NSUserDomainMask, YES) objectAtIndex: 0];

NSLog (@ "cache: % @", cachePath );

// Obtain the tmp directory

NSString * tmpPath = NSTemporaryDirectory ();

NSLog (@ "tmp: % @", tmpPath );

 

1.2 create directories and files

// Obtain the root directory

NSString * homePath = NSHomeDirectory ();

// Creates a file manager.

NSFileManager * fileMgr = [NSFileManager defaultManager];

// Concatenate the path of the file to be created

NSString * filePath = [NSString stringWithFormat: @ "% @/myFolder", homePath];

// Create a file directory

// The first parameter is used to input the directory of the file to be created. The second parameter is used to determine whether to create a folder that does not exist. yes indicates creation.

BOOL isOk = [fileMgr createDirectoryAtPath: filePath withIntermediateDirectories: YES attributes: nil error: nil];

If (isOk ){

NSLog (@ "successfully created the file directory ");

}

NSString * string = @ "I love to remember the lyrics ";

// Write the content to the specified file in the specified path

BOOL isWriteOk = [string writeToFile: [NSString stringWithFormat: @ "% @/1.txt", filePath] atomically: YES encoding: NSUTF8StringEncoding error: nil];

If (isWriteOk ){

NSLog (@ "file written successfully ");

}

// Save the Array

NSArray * array = @ [@ "I am a", @ "I Am a three", @ "I Am a week 7"];

BOOL isWriteOK1 = [array writeToFile: [NSString stringWithFormat: @ "% @/2.txt", filePath] atomically: YES];

If (isWriteOK1 ){

NSLog (@ "array file written successfully ");

}

// Save the dictionary

NSDictionary * dic =@{@ "key": @ "value "};

BOOL isWriteOK2 = [dic writeToFile: [NSString stringWithFormat: @ "% @/3.txt", filePath] atomically: YES];

If (isWriteOK2 ){

NSLog (@ "dictionary file written successfully ");

}

 

2. Rename the file

 

// Obtain the root directory

NSString * homePath = NSHomeDirectory ();

// Creates a file manager.

NSFileManager * fileMgr = [NSFileManager defaultManager];

// Concatenate the path of the file to be created

NSString * filePath = [NSString stringWithFormat: @ "% @/myFolder/1.txt", homePath];

[FileMgr moveItemAtPath: filePath toPath: [NSString stringWithFormat: @ "% @/ai.txt", homePath] error: nil];

 

3. delete an object

// Object that declares an error message

NSError * error;

// Obtain the root directory

NSString * homePath = NSHomeDirectory ();

// Creates a file manager.

NSFileManager * fileMgr = [NSFileManager defaultManager];

// Concatenate the path of the file to be created

NSString * filePath = [NSString stringWithFormat: @ "% @/myFolder/3.txt", homePath];

// Delete an object

// If NO is returned for method execution, error will save the error message. If YES is returned for method execution, error = nil

BOOL isok = [fileMgr removeItemAtPath: filePath error: & error];

If (isok ){

NSLog (@ "File deleted ");

}

Else

{

NSLog (@ "failed to delete file ");

// Print the error message

NSLog (@ "% @", error. localizedDescription );

}

 

Delta [extension] NSError class, which is an error information class

// Delete an object

// If NO is returned for method execution, error will save the error message. If YES is returned for method execution, error = nil

BOOL isok = [fileMgr removeItemAtPath: filePath error: & error];

 

4. Delete all files in the directory

// Obtain the root directory

NSString * homePath = NSHomeDirectory ();

// Creates a file manager.

NSFileManager * fileMgr = [NSFileManager defaultManager];

// Concatenate the path of the file to be created

NSString * filePath = [NSString stringWithFormat: @ "% @/myFolder/3.txt", homePath];

// If the deleted directory does not contain specific files, the entire directory is deleted.

[FileMgr removeItemAtPath: [NSString stringWithFormat: @ "% @/myFolder/", homePath] error: nil];

 

5. Get all files in the directory

// Obtain the root directory

NSString * homePath = NSHomeDirectory ();

// Creates a file manager.

NSFileManager * fileMgr = [NSFileManager defaultManager];

// Concatenate the path of the file to be created

NSString * filePath = [NSString stringWithFormat: @ "% @/myFolder/", homePath];

// Obtain all files in the current directory, including hidden files

NSArray * allFile = [fileMgr contentsOfDirectoryAtPath: filePath error: nil];

NSLog (@ "% @", allFile );

// Obtain all files in the current directory and subdirectory

NSArray * subAllFile = [fileMgr subpathsOfDirectoryAtPath: filePath error: nil];

6. File Attributes

// Obtain the root directory

NSString * homePath = NSHomeDirectory ();

// Creates a file manager.

NSFileManager * fileMgr = [NSFileManager defaultManager];

// Concatenate the path of the file to be created

NSString * filePath = [NSString stringWithFormat: @ "% @/myFolder/3.txt", homePath];

NSDictionary * fileAttribute = [fileMgr fileAttributesAtPath: filePath traverseLink: YES];

// Obtain the Object Attributes

NSData * data = [fileAttribute objectForKey: NSFileModificationDate];

NSLog (@ "file creation date: % @", data );

// Get file attributes 2 (*)

NSDictionary * dic1 = [fileMgr attributesOfItemAtPath: filePath error: nil];

NSLog (@ "Print attributes % @", dic1 );

// File size in bytes

NSNumber * number = [fileAttribute objectForKey: NSFileSize];

NSLog (@ "file size: % @", number );

// Determine whether a file exists

NSFileManager * manager = [NSFileManager defamanager manager];

BOOL isExist = [manager fileExistsAtPath: filePath];