NSUserDefaults保存用户名和密码
#import "ViewController.h" @interface ViewController () @property (weak, nonatomic) IBOutlet UITextField *nameTextField; @property (weak, nonatomic) IBOutlet UITextField *ageTextField; @end @implementation ViewController - (void)viewDidLoad { [super viewDidLoad]; //1.测试部分:获取沙盒的Library目录 NSArray *libraryPaths = NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES); NSString *libraryPath = [libraryPaths lastObject]; NSLog(@"libraryPath:%@",libraryPath); //2.初始化数据(从第四步保存的数据,读取它,并显示) [self initDataByUserDefault]; //3.在用户将后台程序移除后,需要知道针对这个动作的触发时间/方法(通知) [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(applicationWillDidEnterBackground:) name:UIApplicationDidEnterBackgroundNotification object:[UIApplication sharedApplication]]; //4.在后面 } - (void)initDataByUserDefault{ //获取全局的NSUserDefaults对象 NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults]; //使用defaults对象来获取保存的数据 NSString *nameStr = [defaults objectForKey:@"name"]; NSString *ageStr = [defaults objectForKey:@"age"]; //将上步获取的数据,赋值给nameTextField if (nameStr) { self.nameTextField.text = nameStr; } if (ageStr) { self.ageTextField.text = ageStr; } } - (void)applicationWillDidEnterBackground:(NSNotification *)notitication{ NSLog(@"测试:进入后台时机"); //4.在触发方法中去保存你要保存的数据。 NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults]; [defaults setObject:self.nameTextField.text forKey:@"name"]; [defaults setObject:self.ageTextField.text forKey:@"age"]; //强制将用户输入的名字和年龄数据保存到硬盘中 //这里不是自己决定的,由系统决定 ,存在Library目录下。 [defaults synchronize]; } @end
这段代码也可以根据自己的需要进行简化,比如说我是要在点击登录之后,触发保存UserDefault
- (void)viewDidLoad { [super viewDidLoad]; NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults]; NSString *name = [userDefaults objectForKey:@"user"]; NSString *pwd = [userDefaults objectForKey:@"pwd"]; if (name) { self.userName.text = name; } if (pwd) { self.passWord.text = pwd; } } - (IBAction)login:(id)sender { NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults]; [userDefaults setObject:self.userName.text forKey:@"user"]; [userDefaults setObject:self.passWord.text forKey:@"pwd"];
[userDefaults synchronize];
BViewController *BVC = [[BViewController alloc] init]; [self.navigationController pushViewController:BVC animated:YES]; }
NSUserDefaults适合存储轻量级的本地数据,比如要保存一个登陆界面的数据,用户名、密码之类的,个人觉得使用NSUserDefaults是首选。下次再登陆的时候就可以直接从NSUserDefaults里面读取上次登陆的信息咯。
因为如果使用自己建立的plist文件什么的,还得自己显示创建文件,读取文件,很麻烦,而是用NSUserDefaults则不用管这些东西,就像读字符串一样,直接读取就可以了。
NSUserDefaults支持的数据格式有:NSNumber(Integer、Float、Double),NSString,NSDate,NSArray,NSDictionary,BOOL类型。
官方文档解释:
The NSUserDefaults class provides convenience methods for accessing common types such as floats, doubles, integers, Booleans, and URLs. A default object must be a property list, that is, an instance of (or for collections a combination of instances of): NSData, NSString, NSNumber, NSDate, NSArray, or NSDictionary. If you want to store any other type of object, you should typically archive it to create an instance of NSData.
翻译:
NSUserDefaults类提供了便利的方法来访问常见类型如浮点,双精度,整数,布尔和url。一个默认的对象必须是一个属性列表,也就是说,的一个实例(或集合的组合的实例):NSData,NSString,NSNumber,NSDate,NSArray或NSDictionary。如果你想存储其他类型的对象,通常你应该存档NSData它来创建一个实例。