UI Basics: Datapersistent. Sandbox

Sandbox is a specific folder generated for each application, the name of the folder consists of a hexadecimal data, each application's sandbox file name is not the same, is randomly generated by the system.

Sandbox home directory:

NSString *homepath = Nshomedirectory ();

There are three main directories in the Sandbox folder: 1.Documents 2.Library 3tmp

1.Documents storage is some of the more important files, but the documents placed in documents cannot be too large.

2.Library is a repository that stores some of the less important data, relatively larger, with two subfolders: caches folder, for cache files, image cache, video cache, Web cache, application cache is to clear this folder, Preferences folder, System Preferences, user settings for the application, such as: User name and password. Perferences path cannot be found by Nsuserdefaults

3.tmp store Some temporary files, such as the download of compressed package zip, decompression immediately after the removal of the compressed package.

Nssearchpathdirectory This class is used to find the file directory.

such as: nsstring *documentspath = [Nssearchpathfordirectoriesindomains (nsdocumentdirectory, NSUserDomainMask, YES) Firstobject];

First parameter: Ask for a price name

Second parameter: Determining the search Domain

Third parameter: Determines whether it is a relative or absolute path, yes absolute NO relative

NSBundle package file//equivalent to right-click to display package contents

iOS8 before the package and sandbox are in the same directory, after IOS8, the app is stored separately in a separate file directory.

The. App files can only be read and not written (readOnly), downloaded from the AppStore is the package, the program is uploaded when the package.

Nsfilemanager file Management tool, used primarily for adding. Delete. move. Copy, etc., inherit from NSObject.

The following code example:

I. Create an image file under the caches folder

1. Get the caches file path

NSString *cachespath = [Nssearchpathfordirectoriesindomains (nscachesdirectory, Nsuserdomainmask, YES) firstObject];/ /Get Caches Path First

2. Stitching Image Folder path

NSString *imagepath = [Cachespath stringbyappendingpathcomponent:@ "Imagessss"]

Stringbyappendingformat stitching on what is what;

Stringbyappendingpathextension will add one before stitching the content.

Stringbyappendingstring stitching on what is what

3. Create a File Manager

Nsfilemanager is a single case

Nsfilemanager *manager = [Nsfilemanager Defaultmanager];

4. First determine if this folder exists

BOOL isexist = [manager Fileexistsatpath:imagepath];

if (!isexist) {

does not exist

BOOL issucess = [Manager createdirectoryatpath:imagepath withintermediatedirectories:yes Attributes:nil Error:nil];

NSLog (@ "%@", issucess @ "Create succeeded": @ "Create failed");

}

deleting files

if ([manager Fileexistsatpath:imagepath]) {

BOOL issucess = [manager Removeitematpath:imagepath Error:nil];

NSLog (@ "%@", issucess @ "Delete succeeded": @ "Delete failed");         

}

Two. Copy the file and copy the Plist file from the package to the image folder

1. Get the path to the plist file first, the file must be present in advance

NSString *bundlepath = [[NSBundle mainbundle] pathforresource:@ "NB" oftype:@ "plist"];

2. Get the destination path, which is the path to the image in the sandbox

NSString * Nbpath = [ImagePath stringbyappendingpathcomponent:@ "Nb.plist"];

3. Start copying

if (![ Manager Fileexistsatpath:nbpath]) {

Copy when file path is not present

BOOL issuccess = [manager Copyitematpath:bundlepath Topath:nbpath Error:nil];

NSLog (@ "%@", issuccess @ "copy succeeded": @ "copy failed");

}

three. Move the file and move the Nb.plist file under Nbpath to under Document

1. Move the previous path Nbpath

2. Get the documents path and then splice @ "Nb.plist"

NSString *topath = [[Nssearchpathfordirectoriesindomains (NSDocumentDirectory, Nsuserdomainmask, YES) FirstObject] stringbyappendingpathcomponent:@ "Nb.plist"];

3. Mobile

BOOL issuccess = [manager Moveitematpath:nbpath Topath:topath Error:nil];

NSLog (@ "%@", Issuccess @ "mobile success": @ "Move failed");

data persistence for Nsuserdefaults

Nsuserdefaults inherit from NSObject, is also a singleton, through KVC mode to assign values, access to data when the contents of the operation, are stored in the Perference

To create a user Index object

Nsuserdefaults *defaults = [Nsuserdefaults standarduserdefaults];

[Defaults setinteger:100 forkey:@ "Money"];

[Defaults synchronize];//Synchronize Now, as soon as you modify the plist files in the Perferences file will be synchronized immediately.

Nsuserdefault can also manipulate other data types: Nsdictionary, Nsarray,nsstring,nsdata,nsnumber,bool,nsinteger

Nsuserdefaults generally stores some smaller data, most of which are used to store values

Impersonate the first login:

Nsuserdefaults *userdefault = [Nsuserdefaults standarduserdefaults];

BOOL IsFirst = [Userdefault boolforkey:@ "IsFirst"];

if (IsFirst = = NO) {

NSLog (@ "First time login");

[Userdefault setbool:yes forkey:@ "IsFirst"];

[Userdefault Synchronize];

}else{

NSLog (@ "Not the first time to login");

}

------------------------------------------data is written to the file-----------------------------------------

A. String is written to the file, and the string is written to the Documents folder

1. Get the document file path

NSString *docmentspath = [Nssearchpathfordirectoriesindomains (nsdocumentdirectory, NSUserDomainMask, YES) Firstobject];

2.string.txt is the string to write to the file, stitching.

nsstring *stringpath = [Docmentspath stringbyappendingpathcomponent:@ "String.txt"];

3. Prepare the string to be written

NSString *string = @ "Ma Zhen and Uniqlo which one do you choose?";

4. Write

Nserror *error = nil;

BOOL issuccess = [string Writetofile:stringpath atomically:yes encoding:nsutf8stringencoding error:&error];

NSLog (@ "%@", issuccess @ "string Write succeeded": @ "string write Failed");

First parameter: The file path to be written, if this file is not in the file path, a file is created automatically

Second parameter: Determine if auxiliary files need to be generated, in order to protect security under multithreading.

Third parameter: encoding format.

Fourth parameter: Error

String value operation

NSString *getstring = [[NSString alloc]initwithcontentsoffile:stringpath encoding:nsutf8stringencoding Error:nil];

NSLog (@ "%@", getString);

Two. Write the array, write to the Array.txtzhong under the library path

1. Get the Library path

NSString *libraraypath = [Nssearchpathfordirectoriesindomains (nslibrarydirectory, Nsuserdomainmask, YES) firstObject ];

2. Stitching the array.txt into the Librarypathhou

NSString *arraypath = [Libraraypath stringbyappendingpathcomponent:@ "Array.txt"];

3. Preparing an array for writing to a file

Nsarray *array = @[@ "dog", @ "small fish", @ "Mimi", @ "Shanbao"];

4. Write

BOOL issuccess = [array Writetofile:arraypath atomically:yes];

NSLog (@ "%@", issuccess @ "Array write succeeded": @ "Array write failed");

Array Read

Nsarray *getarray = [Nsarray Arraywithcontentsoffile:arraypath];

NSLog (@ "%@", GetArray);

Three. The dictionary is written to the file and written to the dictionary.txt under caches.

1. Get the caches path now

NSString *cachespath = [Nssearchpathfordirectoriesindomains (nscachesdirectory, Nsuserdomainmask, YES) firstObject];

2. Stitching

NSString * Dictionarypath = [Cachespath stringbyappendingpathcomponent:@ "Dictionary.txt"];

3. Prepare a dictionary for writing

Nsdictionary *dictionary = @{@ "a": @ "123", @ "B": @ "456", @ "C": @ "789"};

4. Write

BOOL issuccess = [dictionary Writetofile:dictionarypath atomically:yes];

NSLog (@ "%@", issuccess @ "Dictionary write succeeded": @ "dictionary write Failed");

Read

Nsdictionary *getdictionary = [Nsdictionary Dictionarywithcontentsoffile:dictionarypath];

NSLog (@ "%@", getdictionary);

-----------------------------------------------NSData (binary stream) file write------------------------------

Data.txt written under TEM

1. Get the road strength of the TEM

NSString *tmppath = Nstemporarydirectory ();

2.data.txt Stitching to Tmppath

NSString *datapath = [Tmppath stringbyappendingpathcomponent:@ "Data.txt"];

3. Preparing the NSData object for writing

NSString *string = @ "Uncle, let's have a date!";

NSData *data = [string datausingencoding:nsutf8stringencoding];//strings converted to NSData

4. Write

BOOL issuccess = [data Writetofile:datapath atomically:yes];

NSLog (@ "%@", issuccess @ "Data write succeeded": @ "Data write Failed");

Data from the file to take the value

NSData *getdata = [NSData Datawithcontentsoffile:datapath];

NSLog (@ "%@", getData);

NSString *getstring = [[NSString alloc]initwithdata:getdata encoding:nsutf8stringencoding];

NSLog (@ "%@", getString);

----------------------------------------------archiving and anti-archiving of complex objects-----------------------------------

A complex object cannot write to a file, and to write a complex object to a file, it must be converted to data (a binary stream) to be written.

Archive: The essence of archiving is to convert other types of data first to NSData and then to files. Here is an example of a person as a complex object.

Complex objects that are capable of archiving and anti-archiving must comply with the Nscoding protocol.

I. Archiving

1. Create a complex object person

Person *person = [Person alloc]initwithname:@ "Rose" gender:@ "Girl" age:18];

2. Create a variable data storage compressed

Nskeyedarchiver compression tool, inherited from Nscoder, mainly used for encoding

Nsmutabledata *data= [nsmutabledata data];

Nskeyedarchiver *archiver =[[nskeyedarchiver Alloc]initforwritingwithmutabledata:data];

3. Compress the person object to data using the compression tool

[Archiver encodeobject:person forkey:@ "person"];

4. Complete the compression, need to stop the compression tool

[Archiver finishencoding];

5. Write the compressed file to the Person.txt file

NSString *homepath = Nshomedirectory ();

NSString *personpath = [HomePath stringbyappendingpathcomponent:@ "Perosn.txt"];

BOOL issuccess = [data Writetofile:personpath atomically:yes];

NSLog (@ "%@", issuccess @ "person writes successfully": @ "person writes failed");

Two. Anti-archiving

The reading of a complex object is called an anti-archive

Nskeyedunarchiver Anti-archiving tool

1. Get the data in the file, a. File path B. Find a data object to receive read results

NSData *undata = [NSData Datawithcontentsoffile:personpath];

2. Creating an anti-archiving tool

Nskeyedunarchiver *unarchiver = [[Nskeyedunarchiver alloc]initforreadingwithdata:undata];

3. Unzip

Person *unperson = [unarchiver decodeobjectforkey:@ ' person '];

4. Stop decompression

[Unarchiver finishdecoding];

NSLog (@ "%@", Unperson);

Archiving and anti-archiving of ~~~~~~ arrays ~~~~~~~~

If a collection wants to be archived and archived, the elements inside it must also follow the Nscoding protocol.

Person *person1 = [Person alloc]initwithname:@ "Fan Bingbing" gender:@ "male" age:30];

Person *person2 = [Person alloc]initwithname:@ "big black Bull" gender:@ "female" age:28];

Nsarray *array = @[person1,person2];

Create compressed data

Nsmutabledata *data = [Nsmutabledata data];

Creation of archiving tools

Nskeyedarchiver *archiver = [[Nskeyedarchiver alloc]initforwritingwithmutabledata:data];

Compressing an archived object

[Archiver encodeobject:array forkey:@ "Array"];

Compression end

[Archiver finishencoding];

Store the file in the TMP directory, array.txt

NSString *tmppath = Nstemporarydirectory ();

NSString *arraypath = [Tmppath stringbyappendingpathcomponent:@ "Array.txt"];

BOOL issuccess = [data Writetofile:arraypath atomically:yes];

NSLog (@ "%@", issuccess @ "Array write succeeded": @ "Array write failed");

Initializing Undata via file path

NSData *undata = [NSData Datawithcontentsoffile:arraypath];

Create an anti-archive object

Nskeyedunarchiver *unarchiver = [[Nskeyedunarchiver alloc]initforreadingwithdata:undata];

Extracting data

Nsarray *unarray = [unarchiver decodeobjectforkey:@ "Array"];

Stop the anti-archiving tool

[Unarchiver finishdecoding];

NSLog (@ "%@%@", unarray[0],unarray[1]);

UI Basics: Datapersistent. Sandbox