NSUserDefaults 用户轻量级的数据持久化 (留用)

#import <Foundation/NSObject.h>@class NSArray, NSData, NSDictionary, NSMutableDictionary, NSString, NSURL;FOUNDATION_EXPORT NSString * const NSGlobalDomain;FOUNDATION_EXPORT NSString * const NSArgumentDomain;FOUNDATION_EXPORT NSString * const NSRegistrationDomain;@interface NSUserDefaults : NSObject {@private    NSInteger _unused;    void *_reserved[4];}+ (NSUserDefaults *)standardUserDefaults;+ (void)resetStandardUserDefaults;- (id)init;- (id)initWithUser:(NSString *)username;- (id)objectForKey:(NSString *)defaultName;- (void)setObject:(id)value forKey:(NSString *)defaultName;- (void)removeObjectForKey:(NSString *)defaultName;- (NSString *)stringForKey:(NSString *)defaultName;- (NSArray *)arrayForKey:(NSString *)defaultName;- (NSDictionary *)dictionaryForKey:(NSString *)defaultName;- (NSData *)dataForKey:(NSString *)defaultName;- (NSArray *)stringArrayForKey:(NSString *)defaultName;- (NSInteger)integerForKey:(NSString *)defaultName;- (float)floatForKey:(NSString *)defaultName;- (double)doubleForKey:(NSString *)defaultName;- (BOOL)boolForKey:(NSString *)defaultName;- (NSURL *)URLForKey:(NSString *)defaultName NS_AVAILABLE(10_6, 4_0);- (void)setInteger:(NSInteger)value forKey:(NSString *)defaultName;- (void)setFloat:(float)value forKey:(NSString *)defaultName;- (void)setDouble:(double)value forKey:(NSString *)defaultName;- (void)setBool:(BOOL)value forKey:(NSString *)defaultName;- (void)setURL:(NSURL *)url forKey:(NSString *)defaultName NS_AVAILABLE(10_6, 4_0);- (void)registerDefaults:(NSDictionary *)registrationDictionary;- (void)addSuiteNamed:(NSString *)suiteName;- (void)removeSuiteNamed:(NSString *)suiteName;- (NSDictionary *)dictionaryRepresentation;- (NSArray *)volatileDomainNames;- (NSDictionary *)volatileDomainForName:(NSString *)domainName;- (void)setVolatileDomain:(NSDictionary *)domain forName:(NSString *)domainName;- (void)removeVolatileDomainForName:(NSString *)domainName;- (NSArray *)persistentDomainNames;- (NSDictionary *)persistentDomainForName:(NSString *)domainName;- (void)setPersistentDomain:(NSDictionary *)domain forName:(NSString *)domainName;- (void)removePersistentDomainForName:(NSString *)domainName;- (BOOL)synchronize;- (BOOL)objectIsForcedForKey:(NSString *)key;- (BOOL)objectIsForcedForKey:(NSString *)key inDomain:(NSString *)domain;@endFOUNDATION_EXPORT NSString * const NSUserDefaultsDidChangeNotification;#if (TARGET_OS_MAC && !(TARGET_OS_EMBEDDED || TARGET_OS_IPHONE)) || TARGET_OS_WIN32/* The following keys and their values are deprecated in Mac OS X 10.5 "Leopard". Developers should use NSLocale, NSDateFormatter and NSNumberFormatter to retrieve the values formerly returned by these keys. */FOUNDATION_EXPORT NSString * const NSWeekDayNameArray NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSShortWeekDayNameArray NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSMonthNameArray NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSShortMonthNameArray NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSTimeFormatString NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSDateFormatString NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSTimeDateFormatString NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSShortTimeDateFormatString NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSCurrencySymbol NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSDecimalSeparator NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSThousandsSeparator NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSDecimalDigits NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSAMPMDesignation NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSHourNameDesignations NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSYearMonthWeekDesignations NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSEarlierTimeDesignations NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSLaterTimeDesignations NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSThisDayDesignations NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSNextDayDesignations NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSNextNextDayDesignations NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSPriorDayDesignations NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSDateTimeOrdering NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSInternationalCurrencyString NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSShortDateFormatString NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSPositiveCurrencyFormatString NS_DEPRECATED(10_0, 10_5, NA, NA);FOUNDATION_EXPORT NSString * const NSNegativeCurrencyFormatString NS_DEPRECATED(10_0, 10_5, NA, NA);#endif

1、NSUserDefaults引用：

NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];

2、数据保存

[userDefaults setInteger:1 forKey:@"postsArray"];

[userDefaults synchronize];

3、数据读取

int i = [userDefaults integerForKey:@"postsArray"];

4、其他数据存取

@class NSArray, NSData, NSDictionary, NSMutableDictionary, NSString, NSURL;

(1)保存数据：

NSData *redColor = [NSKeyedArchiver archivedDataWithRootObject:[UIColor redColor]];

[[NSUserDefaults standardUserDefaults]setObject:redColor forKey:@"redColor"];

(2)读取数据：

NSData *redColor = [[NSUserDefaults standardUserDefaults]objectForKey:@"redColor"];

UIColor *redColor = [NSKeyedUnarchiver unarchiveObjectWithData:redColor];

NSUserDefaults *switch = [NSUserDefaults standardUserDefaults];

[switch setInteger:1 forKey:@"switch"];

 [switch synchronize];