让NSUserDefaults使用起来像对象一样容易

巧妙的设计，是为了简化开发提升效率而存在。

设计要点：

1. 单例模式

2. 重写setter，getter方法

3. 专门的类来管理单例

使用时候的详情：

源码：

SharedInstance.h 与 SharedInstance.m

//
//  SharedInstance.h
//  NSUserDefault
//
//  Created by YouXianMing on 14/12/5.
//  Copyright (c) 2014年 YouXianMing. All rights reserved.
//

#import <Foundation/Foundation.h>
#import "NSUserDefaultsObject.h"

/**
 *  单例管理器
 */
@interface SharedInstance : NSObject

+ (NSUserDefaultsObject *)defaultsObject;

@end

//
//  SharedInstance.m
//  NSUserDefault
//
//  Created by YouXianMing on 14/12/5.
//  Copyright (c) 2014年 YouXianMing. All rights reserved.
//

#import "SharedInstance.h"

static NSUserDefaultsObject *_defaultObject = nil;

@implementation SharedInstance

/**
 *  构造单例的类方法
 */
+ (void)initialize {
    if (self == [SharedInstance class]) {
        _defaultObject = [NSUserDefaultsObject new];
    }
}

+ (NSUserDefaultsObject *)defaultsObject {
    return _defaultObject;
}

@end

NSUserDefaultsObject.h 与 NSUserDefaultsObject.m

//
//  NSUserDefaultsObject.h
//  NSUserDefault
//
//  Created by YouXianMing on 14/12/5.
//  Copyright (c) 2014年 YouXianMing. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface NSUserDefaultsObject : NSObject

@property (nonatomic, strong) NSString  *name;

@end

//
//  NSUserDefaultsObject.m
//  NSUserDefault
//
//  Created by YouXianMing on 14/12/5.
//  Copyright (c) 2014年 YouXianMing. All rights reserved.
//

#import "NSUserDefaultsObject.h"

@implementation NSUserDefaultsObject

#pragma mark - 重写setter，getter方法
@synthesize name = _name;
- (void)setName:(NSString *)name {
    [[NSUserDefaults standardUserDefaults] setValue:name forKey:@"name"];
}
- (NSString *)name {
    return [[NSUserDefaults standardUserDefaults] valueForKey:@"name"];
}

@end

核心源码：