文件管理类（NSFileManager,NSUserDefaults,NSKeyedUnarchiver）

1.LXFileManager.h

#import <Foundation/Foundation.h>

/// 文件管理类
@interface LXFileManager : NSObject

/// 把对象归档存到沙盒里
+(void)saveObject:(id)object byFileName:(NSString*)fileName;
/// 通过文件名从沙盒中找到归档的对象
+(id)getObjectByFileName:(NSString*)fileName;

/// 根据文件名删除沙盒中的 plist 文件
+(void)removeFileByFileName:(NSString*)fileName;

/// 存储用户偏好设置 到 NSUserDefults
+(void)saveUserData:(id)data forKey:(NSString*)key;

/// 读取用户偏好设置
+(id)readUserDataForKey:(NSString*)key;

/// 删除用户偏好设置
+(void)removeUserDataForkey:(NSString*)key;

@end

2.LXFileManager.m

#import "LXFileManager.h"

@implementation LXFileManager

/// 把对象归档存到沙盒里
+(void)saveObject:(id)object byFileName:(NSString*)fileName
{
    NSString *path  = [self appendFilePath:fileName];
    
    [NSKeyedArchiver archiveRootObject:object toFile:path];
    
}
/// 通过文件名从沙盒中找到归档的对象
+(id)getObjectByFileName:(NSString*)fileName
{
    
    NSString *path  = [self appendFilePath:fileName];

    return [NSKeyedUnarchiver unarchiveObjectWithFile:path];
}

// 根据文件名删除沙盒中的 plist 文件
+(void)removeFileByFileName:(NSString*)fileName
{
    NSString *path  = [self appendFilePath:fileName];

    [[NSFileManager defaultManager] removeItemAtPath:path error:nil];
}

/// 拼接文件路径
+(NSString*)appendFilePath:(NSString*)fileName
{
   
    NSString *documentsPath = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"];
    
     NSString *file = [NSString stringWithFormat:@"%@/%@.archiver",documentsPath,fileName];

    return file;
}

/// 存储用户偏好设置 到 NSUserDefults
+(void)saveUserData:(id)data forKey:(NSString*)key
{
    if (data)
    {
        [[NSUserDefaults standardUserDefaults]setObject:data forKey:key];
        [[NSUserDefaults standardUserDefaults]synchronize];
    }
}
/// 读取用户偏好设置
+(id)readUserDataForKey:(NSString*)key
{
    return [[NSUserDefaults standardUserDefaults]objectForKey:key];

}
/// 删除用户偏好设置
+(void)removeUserDataForkey:(NSString*)key
{
    [[NSUserDefaults standardUserDefaults]removeObjectForKey:key];
}

@end