将多个键值对存储在 NSUserDefaults 中

Question

我正在IOS（xcode 6.4）中构建一个简单的登录和注册。为了保存用户名和密码，我正在使用NSUserDefaults.但问题是我无法存储多个用户名和密码，因为我将数据保存到同一个密钥。实现它的替代方法是什么。我在stackoverflow上看到了一些类似的问题，但无法理解解决方案。所以任何人都可以用简单的方式解释。HEre 是我的代码：

//function for login pressed
- (IBAction)login:(UIButton *)sender 
{
    NSLog(@"%@,%@",userNameField.text,passwordField.text);
    username = [[NSUserDefaults standardUserDefaults] objectForKey:@"username"];
    password = [[NSUserDefaults standardUserDefaults] objectForKey:@"password"];
    NSLog(@"%@,%@",username,password);
    bool validUser = [username isEqualToString:userNameField.text];
    bool validPassword = [password isEqualToString:passwordField.text];
    if ([self checkWhetherFieldIsEmpty:userNameField.text :passwordField.text]) 
    {
        [self displayAlert:@"All Fileds are mandatory"];
    }
    else if(validUser && validPassword)
    {
        [self displayAlert:@"Successfull Login"] ;
    }
    else{
        // NSLog(@"Invalid username or password");
        [self displayAlert:@"Invalid login or password"];
    }
}
//function when register button is pressed
- (IBAction)register:(UIButton *)sender 
{
    if([[[NSUserDefaults standardUserDefaults] objectForKey:@"username"] isEqualToString:userNameField.text])
    {
        [self displayAlert:@"User already exist"];
        userNameField.text = @"";
        passwordField.text = @"";
    }
    else 
    {
        [[NSUserDefaults standardUserDefaults] setObject:userNameField.text forKey:@"username"];
        [[NSUserDefaults standardUserDefaults] setObject:passwordField.text forKey:@"password"];
        [[NSUserDefaults standardUserDefaults]synchronize];
        NSLog(@"user Created successfully");
        [self displayAlert:@"Registration Successfull"];
    }
}

Answer 1

正如西蒙所指出的，在NSUserDefaults中存储用户名和密码存在安全问题。但是，如果您仍然想这样做，那非常简单。

NSUserDefaults实际上只不过是一个plist，因此您可以将NSArray创建的任意复杂结构存储在NSUserDefaults中NSDictionary。因此，您可以执行以下操作：

NSArray<NSDictionary*>* accounts = @[@{
    @"username" : @"firstUsername",
    @"password" : @"firstPassword"
}, @{
    @"username" : @"secondUsername",
    "password" : @"secondPassword"
}];
[[NSUserDefaults standardUserDefaults] setObject: accounts forKey:@"accounts"];

请注意，您不能只更改一个帐户;如果您需要更改或添加新帐户，则应读取整个结构，将数组和字典转换为可变变体，然后将其一起重写为默认值。

更新

NSUserDefaults* defaults = [NSUserDefaults standardUserDefaults];
NSMutableArray* mutableAccounts = [[defaults objectForKey:@"accounts"] mutableCopy];
// Add or remove accounts:
[mutableAccounts addObject:@{ @"username" : @"newAccount", @"password" : @"newPassword" }];
[mutableAccounts removeObjectAtIndex:0];
[defaults setObject:mutableAccounts forKey:@"accounts"];

Answer 2

您可以简单地将密码保存为密钥用户名的对象，有些人会这样认为：

- (IBAction)login:(UIButton *)sender {
    NSLog(@"%@,%@",userNameField.text,passwordField.text);
    NSString *password = userNameField.text.length > 0? [[NSUserDefaults standardUserDefaults] objectForKey:userNameField.text] : nil;
    bool validUser = passwordField.text.length > 0 ? [passwordField.text isEqualToString:password] : NO;
    if ([self checkWhetherFieldIsEmpty:userNameField.text :passwordField.text]) {
        [self displayAlert:@"All Fileds are mandatory"];
    }
    else if(validUser){
        [self displayAlert:@"Successfull Login"] ;

    }
    else{
        // NSLog(@"Invalid username or password");
        [self displayAlert:@"Invalid login or password"];
    }
}
//function when register button is pressed
- (IBAction)register:(UIButton *)sender {
    //TODO: need check userNameField passwordField is not nil here
    if([[[NSUserDefaults standardUserDefaults] objectForKey:userNameField.text] length] > 0){
        [self displayAlert:@"User already exist"];
        userNameField.text = @"";
        passwordField.text = @"";
    }
    else {
        [[NSUserDefaults standardUserDefaults] setObject:passwordField.text forKey:userNameField.text];
        [[NSUserDefaults standardUserDefaults]synchronize];
        NSLog(@"user Created successfully");
        [self displayAlert:@"Registration Successfull"];
    }
}