Preferences Save user Information

Preferences to save user information .

{

<1> If the user logs on successfully, save the user information . The next time directly from the preferences to read the user information, so that users only need to enter an account and password , and then login can not be entered again .

1;. Login successful , save user Information ( preferences )

2;. Enter again to display the information previously saved directly by the user . Avoid repeated user input .

// Preferences store user information

-(void) Savauserinfo

{

// Instantiation Preference Object ( singleton )

Nsuserdefaults *user = [Nsuserdefaults standarduserdefaults];

// Save user name

[User setobject:selfusername.text forkey:kitusernamekey];

// Save user Password

[User Setobject:pass Forkey:kituserpasskey];

// Sync Save user Information

[User Synchronize];

}

// load user information in preference settings

-(void) Loaduserinfo

{

Nsuserdefaults *user = [Nsuserdefaults standarduserdefaults];

if ([User Objectforkey:itusernamekey]) {

self. username.text = [User Objectforkey:itusernamekey];

}if ([User Objectforkey:ituserpasskey]) {

self. password.text = [User Objectforkey:ituserpasskey];

};

}

<2> user Login business logic

{

//<1> user login requires a separate controller because only one login is required (Login.storyboard). The application needs to have a portal : Main.storyboard:app Main Page

//<2> Determine if the user has successfully logged in ( Judging by user information stored in Preferences )

//1> If the user information is stored in the preferences ( indicating that the previous login was successful), go directly to the app Main Page : Main.storyboard

//2> If there is no user information in the preferences ( first login or log off user information ), enter the login interface : Login.storyboard

//<3> If the user logs in successfully, jump to the app Main Page : Main.storyboard. and save the user information in Preferences .

//<4> If the user clicks the logout button , logs off the user information and returns to the landing page .

}

<3> problem : user password can not be saved in clear text form , need to encrypt the user password before saving !

security Principles for passwords :

1> local and server are not allowed to save the user's password plaintext .

2> on the Network , the transmission of the user's password plaintext is not allowed .

Modern cryptography Anecdotes ! Midway Is. Naval Warfare (AF)

<4> Data encryption Algorithm :

1> symmetric encryption Algorithm : Use the same key for encryption and decryption . Encryption and decryption speed is fast, to ensure that the key security . Suitable for big Data encryption .

2> Asymmetric Encryption Algorithm : use public key encryption , private key decryption . or the public key is decrypted using private key encryption . More secure , but the encryption and decryption speed is slow, suitable for small data encryption .

<5> tips :

OpenSSL: is a strong Secure Sockets Layer cipher library that includes key cryptographic algorithms , common key and certificate encapsulation management functions, and SSL protocols . Provides rich application testing capabilities .

Terminal command :

echo Hello |openssl MD5

echo Hello |openssl SHA1

echo Hello |openssl sha-sha256

echo Hello |openssl sha-sha512

}

Preferences Save user Information