iOS使用NSUserDefaults保存用户名和密码

用户轻量级的数据持久化，主要用于保存用户程序的配置等信息，以便下次启动程序后能恢复上次的设置。该数据实际上是以“键值对”形式保存的（类似于NSDictionary），因此我们需要通过key来读取或者保存数据（value）

1.简单实例

#import "MJViewController.h"

@interface MJViewController ()
- (IBAction)save;
- (IBAction)read;
@end

@implementation MJViewController

- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}

- (IBAction)save {
// 1.利用NSUserDefaults,就能直接访问软件的偏好设置(Library/Preferences)
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];

// 2.存储数据
[defaults setObject:@"mj" forKey:@"account"];
[defaults setObject:@"123" forKey:@"pwd"];
[defaults setInteger:10 forKey:@"age"];
[defaults setBool:YES forKey:@"auto_login"];

// 3.立刻同步
[defaults synchronize];
}

- (IBAction)read {
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];

NSString *account = [defaults objectForKey:@"account"];
BOOL autoLogin = [defaults boolForKey:@"auto_login"];
NSLog(@"%@ -- %d", account, autoLogin);
}