iOS ---沙盒

沙盒

沙盒：每个iOS应用程序都会为自己创建一个文件系统目录（文件夹）， 这个独立、封闭、安全的空间，叫做沙盒。
注：1.每个应用程序都会有一个应用程序沙盒
2.应用程序沙盒就是文件系统目录
沙盒机制：一种安全体系（安全机制）
沙盒机制特点：1.每个应用程序的活动范围都限定在自己的沙盒里
2.不能随意跨越自己的沙盒去访问别的应用程序沙盒中的内容（iOS8已经部分开放访问）
3.应用程序向外请求或接受数据都需要经过权限认证

沙盒目录下有三个文件夹Documents Library(下面有Caches和Preference目录) tmp

Documents目录

保存应用程序运行时生成的需要持久化的数据，Itunes会自动备份该目录

Library目录

存储程序的默认设置和其他状态信息，Itunes会自动备份该目录
1.Library/Caches:存放缓存文件，ITunes不会备份此目录，此目录下文件不会再应用程序退出删除。一般存放体积比较大，不是特别重要的资源。
2.Library/Preference:保存应用的所有偏好设置，iOS的Setting(设置)应用会在该目录中查找应用的设置信息，iTunes会自动备份该目录。注意：不应该直接创建偏好设置文件，而是应该使用NSUserDefaults类来取得和设置应用程序的偏好。

tmp目录

保存应用运行时所需要的临时数据，使用完毕后在将相应的文件从该目录删除。应用没有运行时，系统也有可能会清除该目录下的文件，iTunes不会同步该目录。iPhone重启时，该目录下的文件被删除。

获取沙盒路径

NSString *path = NSHomeDirectory();

获取沙盒下文件目录的路径
有三种获取方法：
1.拼接字符串：

NSString *Documents = [path stringByAppendingString:@"/Documents"];

2.拼接路径

NSString *Documents2 = [path stringByAppendingPathComponent:@"Documents"];

3.系统提供的获取沙盒下目录路径的方法

NSString *Documents3 = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, NO) firstObject];
//NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, NO) 方法返回值为只有一个元素的数组，所以去第一个元素

对于其他两个文件路径的获取方式都一样，系统提供的方法有些区别

NSString *library3 = [NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES) firstObject];
//对于Library文件获取路径方法，只是参数有些不一样
//获取library下的caches
    NSString *cachesStr = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) firstObject];

获取tmp文件夹路径(系统提供的方法)

NSString *tmpStr = NSTemporaryDirectory();

获取程序包路径

    NSString *appPath = [NSBundle mainBundle].resourcePath;

获取程序包内种的一个图片资源(apple.png)路径

    NSString *imagePath = [[NSBundle mainBundle] pathForResource:@"apple" ofType:@"png"];

简单对象的读写(I/O)操作

简单对象：字符串，数组，字典，data

字符串存储

//获取存储的目录
    NSString *str = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
    //在沙盒文件夹下的Documents内创建.txt文件
    NSString *newPath = [str stringByAppendingPathComponent:@"text.txt"];
    //存入内容
    NSString *name = @"蓝欧科技, nihao";
    
    [name writeToFile:newPath atomically:YES encoding:NSUTF8StringEncoding error:nil];

字符串读取

NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
NSString *newPath = [path stringByAppendingString:@"/text.txt"];
NSString *string = [NSString stringWithContentsOfFile:newPath encoding:NSUTF8StringEncoding error:nil];
NSLog(@"%@", string);

数组存储

//获取路径
    NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
    //创建文件
    NSString *newPath = [path stringByAppendingPathComponent:@"array.plist"];
    //存入的数组
    NSArray *nameArr = @[@"zhangsan", @"lisi", @"wangwu"];
    [nameArr writeToFile:newPath atomically:YES];

数组读取

 NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
    NSString *newPath = [path stringByAppendingString:@"/array.plist"];
    //获取数组
    NSArray *array = [NSArray arrayWithContentsOfFile:newPath];
    NSLog(@"%@", array);

字典存储

//获取路径
    NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
    //新建plist文件
    NSString *newPath = [path stringByAppendingPathComponent:@"dict.plist"];
    //要存储的字典
    NSArray *nameArr = @[@"zhangsan",@"lisi"];
    NSDictionary *dict = @{@"a" : @"1", @"b":@"2", @"c" : @"3" , @"name" : nameArr};
//    [dict setValue:nameArr forKey:@"name"];
    [dict writeToFile:newPath atomically:YES];

字典读取

//获取路径
    NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
    //获取plist路径
    NSString *newPath = [path stringByAppendingString:@"/dict.plist"];
    //获取字典
    NSDictionary *dict = [NSDictionary dictionaryWithContentsOfFile:newPath];
    NSLog(@"%@", dict);

NSData类型存储

    NSString *str = @"nihoa";
    //获取地址
    NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
    NSString *dataPath = [path stringByAppendingPathComponent:@"data.plist"];
    NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding];
    //写入文件
    [data writeToFile:dataPath atomically:YES];

NSData读取

  //获取路径
    NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
    NSString *dataPath = [path stringByAppendingPathComponent:@"data.plist"];
    NSData *data = [NSData dataWithContentsOfFile:dataPath];
    NSString *str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    NSLog(@"%@", str);

图片存储

//将图片转成NSData类型在存储
    NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
    //在沙盒问价下面创建一个文件
    NSString *newPath = [path stringByAppendingPathComponent:@"image.png"];
    //需要存储的图片
    NSData *imageData = UIImageJPEGRepresentation([UIImage imageNamed:@"tu.jpg"], 1.0);
    //创建文件并存储
    [imageData writeToFile:newPath atomically:YES];

图片读取

//获取沙盒地址
    NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
    //获取图片data地址
    NSString *newPath = [path stringByAppendingPathComponent:@"image.png"];
    //获取data
    NSData *data = [NSData dataWithContentsOfFile:newPath];
    //获取图片
    UIImage *image = [UIImage imageWithData:data];
    //添加imageView
    UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(100, 200, 150, 150)];
    imageView.image = image;
    [self.view addSubview:imageView];

总结起来就是：简单对象的写就是把在沙盒目录下新建一个文件，将简单对象写入进文件就行，读就是找到目标文件，根据路径创建对象就好

通过文件管理器来操作对象

创建对象

NSString *string = @"hello nihao";
    //根据字符串创建data
    NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding];

创建文件管理器

    NSFileManager *fileManager = [[NSFileManager alloc] init];

存储对象

//向目标文件写入信息
    BOOL save = [fileManager createFileAtPath:[[self documentPath] stringByAppendingPathComponent:@"studenttt.plist"] contents:data attributes:nil];
    if (save) {
        NSLog(@"写入成功");
    }else{
        NSLog(@"写入错误");
    }
//注：[self documentPath]是获取Documents路径
//获取Documents路径
- (NSString *)documentPath {
    return [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
}

读取对象

NSData *mData = [fileManager contentsAtPath:[[self documentPath] stringByAppendingPathComponent:@"studenttt.plist"]];
NSString *mStr = [[NSString alloc] initWithData:mData encoding:NSUTF8StringEncoding];

移动文件

    //移动文件
//atPath:文件存在当前目录
//toPath:目标目录
    BOOL result = [fileManager moveItemAtPath:[[self documentPath] stringByAppendingPathComponent:@"studenttt.plist"] toPath:[[self libraryPath] stringByAppendingPathComponent:@"studenttt.plist"] error:nil];
    if (result) {
        NSLog(@"移动成功");
    }else{
        NSLog(@"移动错误");
    }
//注：[self libraryPath] 获取library文件目录
//获取library路径
- (NSString *)libraryPath {
    return [NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES) firstObject];
}

复制文件

  BOOL result = [fileManager copyItemAtPath:[[self documentPath] stringByAppendingPathComponent:@"studenttt.plist"] toPath:[[self libraryPath] stringByAppendingPathComponent:@"studenttt.plist"] error:nil];
    if (result) {
        NSLog(@"复制成功");
    }else{
        NSLog(@"复制错误");
    }

比较不同路径下的文件内容是否相同

  BOOL result1 = [fileManager contentsEqualAtPath:[[self documentPath] stringByAppendingPathComponent:@"studenttt.plist"] andPath:[[self libraryPath] stringByAppendingPathComponent:@"studenttt.plist"]];
    if (result1) {
        NSLog(@"一致");
    }else{
        NSLog(@"不同");
    }

文件是否存在

  BOOL result = [fileManager fileExistsAtPath:[[self libraryPath] stringByAppendingPathComponent:@"studenttt.plist"]];
    if (result) {
        NSLog(@"存在");
    }else{
        NSLog(@"不存在");
    }

移除文件

    BOOL result = [fileManager removeItemAtPath:[[self libraryPath] stringByAppendingPathComponent:@"studenttt.plist"] error:nil];
    if(result){
        NSLog(@"移除成功");
    }else{
        NSLog(@"移除错误");
    }

创建文件夹

    BOOL result = [fileManager createDirectoryAtPath:[[self documentPath] stringByAppendingPathComponent:@"nimeide"] withIntermediateDirectories:YES attributes:nil error:nil];
    if (result) {
        NSLog(@"创建成功");
    }else{
        NSLog(@"创建错误");
    }

复杂对象的读写---归档和反归档

复杂对象：在Foundation框架内不存在的数据类，如：自定义Person类无法再程序内通过writeToFile：这个方法写入到文件内

如何将复杂对象写入文件?

复杂对象无法通过writeFile:方法进行数据持久化，只能通过将复杂对象转化为NSData（这个步骤就是归档），然后再通过writeTiFile:写入文件

如何从文件中读取复杂对象?

从文件中读取NSData数据，将NSdata转化为复杂对象(这个步骤就是反归档)
注：
1.复杂对象写入文件的过程(复杂对象->归档->NSData->writeToFile:)
2.从文件中读取出复杂对象过程(读取文件->NSData->反归档->复杂对象)

如何进行归档和反归档

1.首先，复杂对象所属的类要遵循<NSCoding>协议

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

2.其次，实现协议中的两个方法

• -(void)encodeWithCoder:(NSCoder *)aCoder;
• -(instancetype)initWithCoder:(NSCoder *)aDecoder

//Person.m
@implementation Person
//当对象进行归档操作的时候，会自动调用这个方法
- (void)encodeWithCoder:(NSCoder *)aCoder{
    [aCoder encodeObject:self.name forKey:@"name"];
    [aCoder encodeObject:self.gender forKey:@"gender"];
    [aCoder encodeInteger:self.age forKey:@"age"];
}
//当对象进行反归档的时候会调用
- (instancetype)initWithCoder:(NSCoder *)aDecoder{
    if (self = [super init]) {
        self.name = [aDecoder decodeObjectForKey:@"name"];
        self.age = [aDecoder decodeIntegerForKey:@"age"];
        self.gender = [aDecoder decodeObjectForKey:@"gender"];
    }
    return self;
}
@end

归档 ----NSKeyedArchiver

  Person *person = [[Person alloc] init];
    person.name = @"小明";
    person.age = 23;
    person.gender = @"男";
    
    //进行归档操作
    //1.创建一个NSmutableData,用来存储归档后的数据
    NSMutableData *mData = [[NSMutableData alloc] init];
    //2.创建归档器
    NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:mData];
    //进行归档
    [archiver encodeObject:person forKey:@"person"];
    //归档结束
    [archiver finishEncoding];
    //存到沙盒的文件夹中
    NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
    NSString *newPath = [path stringByAppendingPathComponent:@"guidang.plist"];
    //存储data
    [mData writeToFile:newPath atomically:YES];

反归档 ----NSKeyedUnarchiver

   //获取路径
    NSString * newPath = [[self documentPath] stringByAppendingPathComponent:@"guidang.plist"];
    //取出数据
    NSData *data = [NSData dataWithContentsOfFile:newPath];
    //创建反归档器
    NSKeyedUnarchiver *unArchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data];
    Person *person = [unArchiver decodeObjectForKey:@"person"];
    //反归档结束
    [unArchiver finishDecoding];
    NSLog(@"name : %@ age : %ld gender : %@", person.name, person.age, person.gender);