One 、 The difference between file manager and file connector

File manager (NSFileManager)

This class mainly refers to the operation of files ( establish / Delete / Name change, etc ) And access to file information .

File connector (NSFileHandle)

This class mainly reads and writes the contents of the file .

Two 、 File manager (NSFileManager)

1、 Create a folder manager 

 NSFileManager *fileManager = [NSFileManager defaultManager];

2、 Create files and write data 

 // Create a folder manager 

NSFileManager *fileManager = [NSFileManager defaultManager];

// Create a path 

NSString *homePath = NSHomeDirectory();

homePath = [homePath stringByAppendingPathComponent:@"string.txt"];

// Initializing a string 
 7 NSString *string = @" Create a file and write data ";

// create a file string.txt And to stirng.txt Add data to 
 // Parameters 1： File path 

// Parameters 2：NSData type 

// Parameters 3： Parameters 

BOOL result = [fileManager createFileAtPath:homePath contents:[string dataUsingEncoding:NSUTF8StringEncoding] attributes:nil];

if (result) {

NSLog(@" success %@", homePath);

} else {

NSLog(@" Failure ");

}

3、 Reading data from a file 

 // Create a folder manager 

NSFileManager *fileManager = [NSFileManager defaultManager];

// Create a path 

NSString *homePath = NSHomeDirectory();

homePath = [homePath stringByAppendingPathComponent:@"string.txt"];

// from string.txt Get data in 

NSData *data = [fileManager contentsAtPath:homePath];

// take NSData Type of data to NSString Data of type , And the output 

NSString *string = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

NSLog(@"string %@", string);

4、 File movement 

 // Create a folder manager 

NSFileManager *fileManager = [NSFileManager defaultManager];

// Create a path 

NSString *homePath = NSHomeDirectory();

NSString *filePath = [homePath stringByAppendingPathComponent:@"string.txt"];

// establish toPath

NSString *toPath = [homePath stringByAppendingPathComponent:@"test.txt"];

// take string.txt The data in is moved to test.txt in , And will string.txt Delete 

BOOL result = [fileManager moveItemAtPath:filePath toPath:toPath error:nil];

if (result) {

NSLog(@" success %@", toPath);

} else {

NSLog(@" Failure ");

}

5、 Copy of documents 

 // Create a folder manager 

NSFileManager *fileManager = [NSFileManager defaultManager];

// Create a path 

NSString *homePath = NSHomeDirectory();

NSString *filePath = [homePath stringByAppendingPathComponent:@"test.txt"];

// establish toPath

NSString *toPath = [homePath stringByAppendingPathComponent:@"copy.txt"];

// take test.txt Copy data from to copy.txt in , Retain test.txt file 

BOOL result = [fileManager copyItemAtPath:filePath toPath:toPath error:nil];

if (result) {

NSLog(@" success %@", toPath);

} else {

NSLog(@" Failure ");

}

6、 Compare the contents of two files to see if they are the same 

 // Create a folder manager 

NSFileManager *fileManager = [NSFileManager defaultManager];

// Create a path 

NSString *homePath = NSHomeDirectory();

NSString *filePath = [homePath stringByAppendingPathComponent:@"test.txt"];

// establish toPath

NSString *toPath = [homePath stringByAppendingPathComponent:@"copy.txt"];

// Compare the contents of the two files 

BOOL result = [fileManager contentsEqualAtPath:filePath andPath:toPath];

if (result) {

NSLog(@" The content is consistent ");

} else {

NSLog(@" Inconsistent content ");

}

7、 Judge whether the file exists 

 // Create a folder manager 

NSFileManager *fileManager = [NSFileManager defaultManager];

// Create a path 

NSString *homePath = NSHomeDirectory();

NSString *filePath = [homePath stringByAppendingPathComponent:@"test.txt"];

// Judge whether the file exists 

BOOL result = [fileManager fileExistsAtPath:filePath];

if (result) {

NSLog(@" File exists ");

} else {

NSLog(@" file does not exist ");

}

8、 remove file 

 // Create a folder manager 

NSFileManager *fileManager = [NSFileManager defaultManager];

// Create a path 

NSString *homePath = NSHomeDirectory();

NSString *filePath = [homePath stringByAppendingPathComponent:@"test.txt"];

// remove file 

BOOL result = [fileManager removeItemAtPath:filePath error:nil];

if (result) {

NSLog(@" Removed successfully ");

} else {

NSLog(@" Remove failed ");

}

9、 Create folder

1、 Create... According to the given folder path 

 // Create a folder manager 

NSFileManager *fileManager = [NSFileManager defaultManager];

// Create a path 

NSString *homePath = NSHomeDirectory();

NSString *filePath = [homePath stringByAppendingPathComponent:@"test1/test2"];

// Create folder 

BOOL result = [fileManager createDirectoryAtPath:filePath withIntermediateDirectories:YES attributes:nil error:nil];

if (result) {

NSLog(@" Create success ");

} else {

NSLog(@" Create failure ");

}

2、 According to the given file path , Create the folder it's in 

 // Create a folder manager 

NSFileManager *fileManager = [NSFileManager defaultManager];

// Create a path 

NSString *homePath = NSHomeDirectory();

NSString *filePath = [homePath stringByAppendingPathComponent:@"test3/test4/hello.txt"];

// Create folder test4

// stringByDeletingLastPathComponent Delete the last one in the path / And what follows 

BOOL result = [fileManager createDirectoryAtPath:[filePath stringByDeletingLastPathComponent] withIntermediateDirectories:YES attributes:nil error:nil];

if (result) {

NSLog(@" Create success ");

} else {

NSLog(@" Create failure ");

}

3、 ... and 、 File connector (NSFileHandle)

NSFileHandle Is very basic, only for the operation of file content ( write in , Read , to update ), It's a NSData Write byte by byte through the connector / Read the file .(NSData <—> NSFileHandle <—> file ).

Use scenarios :
    Partial modification of the contents of the document 、 Additional content .

Use steps
    1). File docking and get a NSFileHandle object .
    2). Read and write operations
    3). Turn off docking

Be careful :NSFileHandle Class does not provide the ability to create files . You have to use NSFileManager Method to create a file . therefore , When using the methods in the table below , It's all about ensuring that the documents already exist , Otherwise return to nil.

1、 Reading data

1、 Read all the data in the file 

 // string.txt Already exist , Get its path 

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

// Create a file connector , And open a file to read 

NSFileHandle *handle = [NSFileHandle fileHandleForReadingAtPath:filePath];

// from string.txt Read all data in 

NSData *data = [handle availableData];

NSString *string = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

NSLog(@"string %@", string);

// Close the file connector 

[handle closeFile];

2、 Read from the specified location to the end of the file

Be careful , When the data in the file is Chinese characters , because utf-8 The Chinese character is three bytes , So the offset has to be 3 Multiple , Otherwise, the data cannot be read 

 // string.txt Already exist , Get its path 

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

// Create a file connector , And open a file to read 

NSFileHandle *handle = [NSFileHandle fileHandleForReadingAtPath:filePath];

// obtain stirng.txt Number of bytes of data in 

NSUInteger length = [[handle availableData] length];

// The offset is half of the file 

[handle seekToFileOffset:length/2.0];

// Gets the offset of the current file 

NSLog(@"%llu", [handle offsetInFile]);

// Read from half of the data , Read to the end of the file 

NSData *data = [handle readDataToEndOfFile];

NSString *string = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

NSLog(@"string %@", string);

[handle closeFile];

3、 Reads data of a specified length from a specified location 

 // string.txt Already exist , Get its path 

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

// Create a file connector , And open a file to read 

NSFileHandle *handle = [NSFileHandle fileHandleForReadingAtPath:filePath];

// obtain stirng.txt Medium data length 

NSUInteger length = [[handle availableData] length];

// The offset is half of the file 

[handle seekToFileOffset:length/2.0];

// Read from half of the data , Read 3 Bytes 

NSData *data = [handle readDataOfLength:];

NSString *string = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

NSLog(@"string %@", string);

[handle closeFile];

2、 Intercepts the file to the specified length 

 // string.txt Already exist , Get its path 

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

// Create a file connector , And open a file to write and read 

NSFileHandle *handle = [NSFileHandle fileHandleForWritingAtPath:filePath];

// Set the length of the file to 21 byte 

[handle truncateFileAtOffset:];

[handle closeFile];

3、 Splice data in the specified location of the file 

 // string.txt Already exist , Get its path 

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

// Create a file connector , And open a file to write ( Or update ) Read 

NSFileHandle *handle = [NSFileHandle fileHandleForWritingAtPath:filePath];

// Search to the end of the file content 

[handle seekToEndOfFile];

NSString *appendStr = @" world";

// Splice strings at the end of the file 

[handle writeData:[appendStr dataUsingEncoding:NSUTF8StringEncoding]];

[handle closeFile];

UI Advanced File manager (NSFileManager) File docking device (NSFileHandle) More articles about

  1. 【 primary 】iOS Learning file manager (NSFileManager) And file docking (NSFileHandle)

    1. File manager (NSFileManager) 1> Main functions and methods The main role : This class mainly refers to the operation of files ( establish / Delete / Name change, etc ) And access to file information . Functional approach : 2> Create folder Create Institute ...

  2. 02-IOSCore - NSFileHandle、 Merge files 、 The file pointer 、 File viewer

    [day0201_NSFileHandle]: File handle 1 NSFileHandle File docking device . File handle Commonly used API: - (NSData *)readDataToEndOfFile; Read data to the end ...

  3. win10 uwp Open file manager and select File

    this paper : Let the file manager select the file , Not getting files from file manager . If some documents have been obtained , So how to select these files from the file manager ? The method is simple to use . Take pictures from the Internet Open the folder and automatically select all files First you need to get the folder , because ...

  4. 2018-8-10-win10-uwp- Open file manager and select File

    title author date CreateTime categories win10 uwp Open file manager and select File lindexi 2018-08-10 19:16:50 +0800 2018 ...

  5. file NSKeyedArchiver De archiving NSKeyedUnarchiver And file management NSFileManager （ File operations ）

    ========================== File operations ========================== One . file NSKeyedArchiver 1. The first way : Store a kind of data . // file ...

  6. Windows Store App JavaScript Development ： File picker

    As in the previous chapter C# What is introduced in the language , File picker is an interface between application and system , The file picker can interact with the file system directly in the application , Access files or folders in different locations , Or store the file in a specified location . The file picker is divided into two parts ...

  7. Imagine again Windows 8 Store Apps (26) - Picker : Custom file selection window , Custom file save window

    original text : Imagine again Windows 8 Store Apps (26) - Picker : Custom file selection window , Custom file save window [ Source download ] Imagine again Windows 8 Store Apps (26) ...

  8. fight to win or die Windows 10 (95) - Picker : Custom file save picker

    [ Source download ] fight to win or die Windows 10 (95) - Picker : Custom file save picker author :webabcd Introduce the battle behind the back Windows 10 And   Picker Custom file save picker Example 1. Show me how to ...

  9. fight to win or die Windows 10 (94) - Picker : Custom file open picker

    [ Source download ] fight to win or die Windows 10 (94) - Picker : Custom file open picker author :webabcd Introduce the battle behind the back Windows 10 And   Picker Custom file open picker Example 1. Show me how to ...

Random recommendation

  1. ( turn ) Walk into JVM, You can catch fish in shallow water

    This is not a description jvm What's the article about , No introduction jvm Cross platform features , It's not about jvm Security features article , It's not the explanation jvm Command operation , Data operations article , This article focuses on the life cycle of types . The life cycle of a type involves : Class loading .j ...

  2. Fraction to Recurring Decimal leetcode

    Given two integers representing the numerator and denominator of a fraction, return the fraction in ...

  3. be based on Python Of Web Application development practice summary

    be based on Python Of Web Application development learning summary Project address This study adopts Flask frame . Develop personal blog system according to the tutorial . The blog interface is shown in the figure . The whole learning process gains a lot , Here is a summary of the study . 1.virtualenv ...

  4. hbase- Data recovery process

    quote <https://blog.csdn.net/nigeaoaojiao/article/details/54909921> hlog Introduce : hlog structure : As you can see from the diagram , For one hl ...

  5. Asp.net Webform Page lifecycle for

    1. Analyze the resource path of the request , Find the corresponding resource file in the directory , If the resource file cannot be found , Then return to 404 error 2. Analysis of resource files Page command , adopt Page Instructions to find code files and classes 3. Compile the page file and class together to generate the final class ( Only in the third quarter ...

  6. Simple web Testing process （ Reprint ）

    Reprinted from http://blog.csdn.net/qq_35885203 1. The interface operation mode is on jmeter Get into jmeter Installation directory bin Under the table of contents , double-click “jmeter.bat” The file can be opened jmeter ...

  7. JS Learning notes （ One ）DOM Events and monitoring

    Three ways to bind an event to an element : 1.HTML Event handler ( It is not recommended to use ) 1 <a onclick="hide()"> 2. Conventional DOM Event handler That is, in the goal DOM event ...

  8. vue nextTick In depth understanding of －vue performance optimization 、DOM Update time 、 Event cycle mechanism

    One . Definition ［nextTick. The event loop ］ nextTick The origin of : because VUE Data driven view update for , It's asynchronous , That is, the moment of data modification , The view will not be updated immediately , It's the same as after all the data changes in an event loop are completed , Then unify the views ...

  9. spring boot(1)-Hello World

    spring boot brief introduction spring boot By spring A new framework officially launched , Yes spring It's highly encapsulated , yes spring The future direction of development .spring boot It has many functions , The main function is ...

  10. Kotlin------ Data types and Syntax

    Today, let's briefly introduce Kotlin Basic syntax . Programming languages are mostly interlinked , I can learn basic knowledge very quickly , The theory is the same , The implementation code language is different . value type Kotlin How to deal with numerical value and java Very similar , But it's not exactly the same . such as ...