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 - 20
2015-11-11 12:10:57.270 01-nsuserdefaults[1595:72935] fetch float - 21.000000
2015-11-11 12:10:57.270 01-nsuserdefaults[1595:72935] fetch double - 22.000000
2015-11-11 12:10:57.271 01-nsuserdefaults[1595:72935] fetch bool - 1
2015-11-11 12:10:57.271 01-nsuserdefaults[1595:72935] fetch NSString - testNSString
2015-11-11 12:10:57.324 01-nsuserdefaults[1595:72935] fetch Date - 2015-11-11 04:10:57 +0000
2015-11-11 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