ISO之NSUserDefaults

NSUserDefaults是一个单例，并且线程安全。它支持的数据类型有：NSNumber（NSInteger、float、double...），NSString，NSDate，NSArray，NSDictionary，BOOL...

NSArry和NSDictionary中存储的也只能是上面这些，不能存储自定义类型，除非自定义类型遵守NSCoding协议并实现相应的方法。

1、先看一下NSUserDefaults里面默认存储的东西

    //获取设备上所有NSUserDefaults的设置    NSDictionary * userDefaultsDict = [[NSUserDefaults standardUserDefaults] dictionaryRepresentation];    NSLog(@"%@", userDefaultsDict);

输出：

2015-11-11 11:03:20.055 01-nsuserdefaults[1035:41606] {    AddingEmojiKeybordHandled = 1;    AppleITunesStoreItemKinds =     (        podcast,        artist,        "itunes-u",        booklet,        document,        movie,        eBook,        software,        "software-update",        "podcast-episode"    );    AppleLanguages =     (        "en-US"    );    AppleLanguagesDidMigrate = "9.1";    AppleLocale = "en_US";    ApplePasscodeKeyboards =     (        "en_US"    );    MSVLoggingMasterSwitchEnabledKey = 0;    NSInterfaceStyle = macintosh;    NSLanguages =     (        "en-US",        en    );}

具体信息不再详细解释，因为我也不是很清楚，0..0

2、NSUserDefaults支持的数据类型

    NSUserDefaults * userDefaults = [NSUserDefaults standardUserDefaults];        int testInt = 20;    float testFloat = 21.00;    double testDouble = 22.000000;    [userDefaults setInteger:testInt forKey:@"testInt"];    [userDefaults setDouble:testDouble forKey:@"testDouble"];    [userDefaults setFloat:testFloat forKey:@"testFloat"];        BOOL testBool = YES;    [userDefaults setBool:testBool forKey:@"testBool"];        NSString * testString = @"testNSString";    [userDefaults setObject:testString forKey:@"testString"];        //NSData读取一张图片    //不能存NSMutableData    NSString * jpgPath = [[NSBundle mainBundle] pathForResource:@"test1" ofType:@"jpg"];    NSData * testData = [NSData dataWithContentsOfFile:jpgPath];    [userDefaults setObject:testData forKey:@"testData"];        //日期    NSDate * testDate = [NSDate date];    [userDefaults setObject:testDate forKey:@"testDate"];        //不能存NSMutableArray    NSArray * testArray = @[@"t1", @"t2", @"t3"];    [userDefaults setObject:testArray forKey:@"testArray"];        //不能存NSMutableDictionary    NSDictionary * testDict = @{@"key1":@"value1", @"key2":@"value2", @"key3":@"value3"};    [userDefaults setObject:testDict forKey:@"testDict"];        [userDefaults synchronize];//同步一下，不写也可以        //注：    //总之不能存可变类型，取的时候也不能用可变类型接收，否则可变类型也变为不可变类型                    //取数据    NSInteger fetchInt = [userDefaults integerForKey:@"testInt"];    NSLog(@"fetch int - %li", (long)fetchInt);        float fetchFloat = [userDefaults floatForKey:@"testFloat"];    NSLog(@"fetch float - %f", fetchFloat);        double fetchDouble = [userDefaults doubleForKey:@"testDouble"];    NSLog(@"fetch double - %f", fetchDouble);        BOOL fetchBool = [userDefaults boolForKey:@"testBool"];    NSLog(@"fetch bool - %i", fetchBool);        NSString * fetchStr = [userDefaults stringForKey:@"testString"];    NSLog(@"fetch NSString - %@", fetchStr);        //取出图片并显示    NSData * fetchData = [userDefaults dataForKey:@"testData"];    UIImage * image = [UIImage imageWithData:fetchData];    UIImageView * imageView = [[UIImageView alloc] initWithFrame:CGRectMake(50, 100, 200, 200)];    imageView.image = image;    imageView.backgroundColor = [UIColor orangeColor];    [self.view addSubview:imageView];            //读取日期类型数据    NSDate * fetchDate = [userDefaults valueForKey:@"testDate"];    NSLog(@"fetch Date - %@", fetchDate);        NSArray * fetchArray = [userDefaults arrayForKey:@"testArray"];    NSLog(@"fetch NSArray - %@", fetchArray);        NSDictionary * fetchDict = [userDefaults dictionaryForKey:@"testDict"];    NSLog(@"fetch NSDictionary - %@", fetchDict);

输出：

2015-11-11 12:10:57.269 01-nsuserdefaults[1595:72935] fetch int - 202015-11-11 12:10:57.270 01-nsuserdefaults[1595:72935] fetch float - 21.0000002015-11-11 12:10:57.270 01-nsuserdefaults[1595:72935] fetch double - 22.0000002015-11-11 12:10:57.271 01-nsuserdefaults[1595:72935] fetch bool - 12015-11-11 12:10:57.271 01-nsuserdefaults[1595:72935] fetch NSString - testNSString2015-11-11 12:10:57.324 01-nsuserdefaults[1595:72935] fetch Date - 2015-11-11 04:10:57 +00002015-11-11 12:10:57.324 01-nsuserdefaults[1595:72935] fetch NSArray - (    t1,    t2,    t3)2015-11-11 12:10:57.324 01-nsuserdefaults[1595:72935] fetch NSDictionary - {    key1 = value1;    key2 = value2;    key3 = value3;}

图片输出：

3、遵守NSCoding协议，使其支持自定义数据类型

person测试类：

#import <Foundation/Foundation.h>@interface Person : NSObject <NSCoding>@property(nonatomic, copy) NSString * name;@property(nonatomic, assign) NSInteger age;@end

#import "Person.h"@implementation Person- (void)encodeWithCoder:(NSCoder *)aCoder{    [aCoder encodeObject:self.name forKey:@"name"];    [aCoder encodeInteger:self.age forKey:@"age"];}- (nullable instancetype)initWithCoder:(NSCoder *)aDecoder{    if (self = [super init]) {        self.name = [aDecoder decodeObjectForKey:@"name"];        self.age = [aDecoder decodeIntegerForKey:@"age"];    }    return self;}@end

测试数据：

    Person * person = [[Person alloc] init];    person.name = @"dzl";    person.age = 25;        NSData * dataPerson = [NSKeyedArchiver archivedDataWithRootObject:person];    NSUserDefaults * userDefaults = [NSUserDefaults standardUserDefaults];    [userDefaults setObject:dataPerson forKey:@"dataPerson"];    [userDefaults synchronize];        //取数据    NSData * fetchDataPerson = [userDefaults objectForKey:@"dataPerson"];    Person * fetchPerson = [NSKeyedUnarchiver unarchiveObjectWithData:fetchDataPerson];    NSLog(@"person.name = %@, person.age = %li", fetchPerson.name, (long)fetchPerson.age);

输出：

2015-11-11 12:31:09.589 01-nsuserdefaults[1756:80720] person.name = dzl, person.age = 25

其实NSString NSDictionary NSData NSDate 等都遵守NSSecureCoding协议，此协议又遵守NSCoding协议