浮点数二进制表示

//获取document目录
    //NSUserDomainMask从用户文件夹开始找 YES代表代表展开路径中的波浪字符“~”
    NSArray *documet=NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
	
    NSString *doc=documet[0];
    //归档 如果归档为plist文件不需要用load的方式加载
    NSString *ahPath=[doc stringByAppendingString:@"array.archive"];
    
    NSArray *arr=@[@"book1",@"book2",@"book3"];
    //归档
    [NSKeyedArchiver archiveRootObject:arr toFile:ahPath];
    //解档
    NSArray *unarray= [NSKeyedUnarchiver unarchiveObjectWithFile:ahPath];
    NSLog(@"array==%@",unarray);

@implementation Person

//归档
-(void)encodeWithCoder:(NSCoder *)aCoder{
    [aCoder encodeObject:_name forKey:@"name"];
    [aCoder encodeInt:_age forKey:@"age"];
    NSData *imageData=UIImagePNGRepresentation(_image);
 
    [aCoder encodeObject:imageData forKey:@"imageData"];
}

//接档
-(id)initWithCoder:(NSCoder *)aDecoder{
    self=[super init];
    if (self) {
        [self setName:[aDecoder decodeObjectForKey:@"name"]];
        [self setAge:[aDecoder decodeIntForKey:@"age"]];
        NSData *imageData=[aDecoder decodeObjectForKey:@"imageData"];
           NSLog(@"%@",imageData);
        [self setImage:[UIImage imageWithData:imageData]];
    }
    return self;
}

+(id)initPersonWithName:(NSString *)name age:(int)age image:(UIImage *)image{
    Person *person=[[Person alloc]init];
    [person setName:name];
    [person setAge:age];
    [person setImage:image];
    return person;
}
@end

@implementation Student
-(id)initWithCoder:(NSCoder *)aDecoder{
    self=[super initWithCoder:aDecoder];
    if (self) {
        _no=[aDecoder decodeObjectForKey:@"no"];
    }
    return self;
}

-(void)encodeWithCoder:(NSCoder *)aCoder{
    [super encodeWithCoder:aCoder];
    [aCoder encodeObject:_no forKey:@"no"];
}

+(id)initPersonWithName:(NSString *)name age:(int)age image:(UIImage *)image no:(NSString *)no{
    Student *stu=[[Student alloc]init];
    [stu setNo:no];
    [stu setAge:age];
    [stu setImage:image];
    [stu setName:name];
    return stu;
}
@end

  NSArray *arry=NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *doc=arry[0];
    Person *person=[Person initPersonWithName:_nameText.text age:_ageText.text.intValue image:_iconView.image];
    NSString *path=[doc stringByAppendingString:@"person.plist"];
    [NSKeyedArchiver archiveRootObject:person toFile:path];

NSArray *arry=NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *dir=arry[0];
    NSString *path=[dir stringByAppendingString:@"person.plist"];
   Person *person= [NSKeyedUnarchiver unarchiveObjectWithFile:path];
    _nameText.text=person.name;
    _ageText.text=[NSString stringWithFormat:@"%d",person.age];
    _iconView.image=person.image;

NSArray *documents = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *path = [documents[0]stringByAppendingPathComponent:@"multiPersonInfo.plist"];
    
    Person *person1=[Person initPersonWithName:@"san" age:_ageText.text.intValue image:_iconView.image];
     Person *person2=[Person initPersonWithName:@"zhang" age:_ageText.text.intValue image:_iconView.image];
    Student *stu=[Student initPersonWithName:@"lisi" age:10 image:_iconView.image no:@"89757"];
    
    // 新建一块可变的数据区
    NSMutableData *data = [NSMutableData data];
    
    // 将数据区连接到一个NSKeyedArchiver对象
    NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc]initForWritingWithMutableData:data];
    
    // 开始存档对象，存档的数据都会存储到NSMutableData中
    [archiver encodeObject:person1 forKey:@"person1"];
    [archiver encodeObject:person2 forKey:@"person2"];
    
    // 存档完毕(一定要调用这个方法！！！)
    [archiver finishEncoding];
    
    // 将存档的数据写入文件
    [data writeToFile:path atomically:YES];

  NSArray *documents = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *path = [documents[0]stringByAppendingPathComponent:@"multiPersonInfo.plist"];
    NSData *data = [NSData dataWithContentsOfFile:path];
    // 根据数据，解析成一个NSKeyedUnarchiver对象
    NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc]initForReadingWithData:data];
    // 恢复对象
    Person *person1 = [unarchiver decodeObjectForKey:@"person1"];
    Person *person2 = [unarchiver decodeObjectForKey:@"person2"];
    // 恢复完毕(一定要调用这个方法)
    [unarchiver finishDecoding];

NSUserDefaults *defaults=[NSUserDefaults standardUserDefaults];
    [defaults setObject:@"张三" forKey:@"userName"];
    [defaults setInteger:10 forKey:@"age"];
    [[NSUserDefaults standardUserDefaults]setObject:@"mimaya" forKey:@"password"];
    //同步  如果不加会延迟
    [defaults synchronize];

NSUserDefaults *defaults=[NSUserDefaults standardUserDefaults];
    NSString *name=[defaults objectForKey:@"userName"];
    NSLog(@"userName=%@",name);

注意：UserDefaults设置数据时，不是立即写入，而是根据时间戳定时地把缓存中的数据写入本地磁盘。所以调用了set方法之后数据有可能还没有写入磁盘，应用程序就终止了，出现以上问题，可以通过调用synchornize方法强制写入。