iOS应用数据存储的常用方式

应用沙盒

模拟器应用沙盒的根路径在:(apple是用户名,6.0是模拟器版本)

/Users/apple/Library/Application Support/iPhoneSimulator/6.0/Applications

应用沙盒结构分析

应用沙盒目录的常见获取方式

NSString *home =NSHomeDirectory();

NSString*documents = [homestringByAppendingPathComponent:@"Documents"];

//不建议采用，因为新版本的操作系统可能会修改目录名

// NSUserDomainMask代表从用户文件夹下找

// YES代表展开路径中的波浪字符“~”

NSArray*array = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, NO);

//在iOS中，只有一个目录跟传入的参数匹配，所以这个集合里面只有一个元素

NSString*documents = [arrayobjectAtIndex:0];

应用沙盒目录的常见获取方式

属性列表

属性列表-归档NSDictionary

//将数据封装成字典

NSMutableDictionary *dict =[NSMutableDictionary dictionary];

[dict setObject:@"母鸡" forKey:@"name"];

[dictsetObject:@"15013141314" forKey:@"phone"];

[dict setObject:@"27"forKey:@"age"];

//将字典持久化到Documents/stu.plist文件中

[dictwriteToFile:path atomically:YES];

属性列表-归档NSDictionary

属性列表-恢复NSDictionary

//读取Documents/stu.plist的内容，实例化NSDictionary

NSDictionary*dict = [NSDictionarydictionaryWithContentsOfFile:path];

NSLog(@"name:%@", [dictobjectForKey:@"name"]);

NSLog(@"phone:%@", [dictobjectForKey:@"phone"]);

NSLog(@"age:%@", [dictobjectForKey:@"age"]);

属性列表-NSDictionary的存储和读取过程

偏好设置

NSUserDefaults *defaults = [NSUserDefaultsstandardUserDefaults];

[defaultssetObject:@"itcast"forKey:@"username"];

[defaultssetFloat:18.0fforKey:@"text_size"];

[defaultssetBool:YESforKey:@"auto_login"];

偏好设置

NSUserDefaults*defaults = [NSUserDefaultsstandardUserDefaults];

NSString*username = [defaultsstringForKey:@"username"];

floattextSize = [defaultsfloatForKey:@"text_size"];

BOOLautoLogin = [defaultsboolForKey:@"auto_login"];

[defaults synchornize];

NSKeyedArchiver

每次归档对象时，都会调用这个方法。一般在这个方法里面指定如何归档对象中的每个实例变量，可以使用encodeObject:forKey:方法归档实例变量

每次从文件中恢复(解码)对象时，都会调用这个方法。一般在这个方法里面指定如何解码文件中的数据为对象的实例变量，可以使用decodeObject:forKey方法解码实例变量

NSKeyedArchiver-归档NSArray

NSKeyedArchiver-归档Person对象（Person.h）

@interface Person : NSObject<NSCoding>
@property (nonatomic, copy) NSString *name;
@property (nonatomic, assign) int age;
@property (nonatomic, assign) float height;
@end

@implementation Person
- (void)encodeWithCoder:(NSCoder *)encoder {
    [encoder encodeObject:self.name forKey:@"name"];
    [encoder encodeInt:self.age forKey:@"age"];
    [encoder encodeFloat:self.height forKey:@"height"];
}
- (id)initWithCoder:(NSCoder *)decoder {
    self.name = [decoder decodeObjectForKey:@"name"];
    self.age = [decoder decodeIntForKey:@"age"];
    self.height = [decoder decodeFloatForKey:@"height"];
    return self;
}
- (void)dealloc {
    [super dealloc];
    [_name release];
}
@end

Person*person =[[[Personalloc] init] autorelease];

person.name= @"MJ";

person.age= 27;

person.height= 1.83f;

[NSKeyedArchiverarchiveRootObject:persontoFile:path];

Person *person =[NSKeyedUnarchiverunarchiveObjectWithFile:path];

NSKeyedArchiver-归档对象的注意

[superencodeWithCode:encode];

确保继承的实例变量也能被编码，即也能被归档

self= [super initWithCoder:decoder];

确保继承的实例变量也能被解码，即也能被恢复

NSData

NSData-归档2个Person对象到同一文件中

归档（编码）
// 新建一块可变数据区
NSMutableData *data = [NSMutableData data];
// 将数据区连接到一个NSKeyedArchiver对象
NSKeyedArchiver *archiver = [[[NSKeyedArchiver alloc] initForWritingWithMutableData:data] autorelease];
// 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];

恢复（解码）
// 从文件中读取数据
NSData *data = [NSData dataWithContentsOfFile:path];
// 根据数据，解析成一个NSKeyedUnarchiver对象
NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data];
Person *person1 = [unarchiver decodeObjectForKey:@"person1"];
Person *person2 = [unarchiver decodeObjectForKey:@"person2"];
// 恢复完毕
[unarchiver finishDecoding];

比如对一个Person对象进行深复制
// 临时存储person1的数据
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:person1];
// 解析data，生成一个新的Person对象
Student *person2 = [NSKeyedUnarchiver unarchiveObjectWithData:data];
// 分别打印内存地址
NSLog(@"person1:0x%x", person1); // person1:0x7177a60
NSLog(@"person2:0x%x", person2); // person2:0x7177cf0

SQLite3

  create table t_person(name, age);

  为了保证可读性，建议还是把字段类型加上：

  create table t_person(name text, age integer);

创建、打开、关闭数据库

//path为：~/Documents/person.db

sqlite3*db;

intresult =sqlite3_open([path UTF8String], &db);

执行不返回数据的SQL语句

char*errorMsg; //用来存储错误信息

char*sql = "create table if notexists t_person(id integer primary key autoincrement, nametext, age integer);";

intresult =sqlite3_exec(db, sql, NULL, NULL, &errorMsg);

带占位符插入数据

char *sql = "insert into t_person(name, age) values(?, ?);";
sqlite3_stmt *stmt;
if (sqlite3_prepare_v2(db, sql, -1, &stmt, NULL) == SQLITE_OK) {
    sqlite3_bind_text(stmt, 1, "母鸡", -1, NULL);
    sqlite3_bind_int(stmt, 2, 27);
}
if (sqlite3_step(stmt) != SQLITE_DONE) {
    NSLog(@"插入数据错误");
}
sqlite3_finalize(stmt);

代码解析：
sqlite3_prepare_v2()返回值等于SQLITE_OK，说明SQL语句已经准备成功，没有语法问题

查询数据

char *sql = "select id,name,age from t_person;";
sqlite3_stmt *stmt;
if (sqlite3_prepare_v2(db, sql, -1, &stmt, NULL) == SQLITE_OK) {
    while (sqlite3_step(stmt) == SQLITE_ROW) {
        int _id = sqlite3_column_int(stmt, 0);
        char *_name = (char *)sqlite3_column_text(stmt, 1);
        NSString *name = [NSString stringWithUTF8String:_name];
        int _age = sqlite3_column_int(stmt, 2);
        NSLog(@"id=%i, name=%@, age=%i", _id, name, _age);
    }
}
sqlite3_finalize(stmt);
代码解析
sqlite3_step()返回SQLITE_ROW代表遍历到一条新记录
sqlite3_column_*()用于获取每个字段对应的值，第2个参数是字段的索引，从0开始

模型文件

模型文件

模型文件

模型文件

NSManagedObject

CoreData主要对象

搭建Core Data上下文环境

NSManagedObjectModel*model = [NSManagedObjectModelmergedModelFromBundles:nil];

NSPersistentStoreCoordinator*psc =[[[NSPersistentStoreCoordinator alloc]initWithManagedObjectModel:model] autorelease];

NSString *docs =[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask,YES) lastObject];

NSURL*url = [NSURLfileURLWithPath:[docsstringByAppendingPathComponent:@"person.data"]];

搭建Core Data上下文环境

添加持久化存储库，这里使用SQLite作为存储库
NSError *error = nil;
NSPersistentStore *store = [psc addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:url options:nil error:&error];
if (store == nil) { // 直接抛异常
    [NSException raise:@"添加数据库错误" format:@"%@", [error localizedDescription]];
}
初始化上下文，设置persistentStoreCoordinator属性
NSManagedObjectContext *context = [[NSManagedObjectContext alloc] init];
context.persistentStoreCoordinator = psc;
// 用完之后，还是要[context release];

传入上下文，创建一个Person实体对象
NSManagedObject *person = [NSEntityDescription insertNewObjectForEntityForName:@"Person" inManagedObjectContext:context];
设置简单属性
[person setValue:@"MJ" forKey:@"name"];
[person setValue:[NSNumber numberWithInt:27] forKey:@"age"];
传入上下文，创建一个Card实体对象
NSManagedObject *card = [NSEntityDescription insertNewObjectForEntityForName:@"Card" inManagedObjectContext:context];
[card setValue:@"4414241933432" forKey:@"no"];
设置Person和Card之间的关联关系
[person setValue:card forKey:@"card"];

利用上下文对象，将数据同步到持久化存储库
NSError *error = nil;
BOOL success = [context save:&error];
if (!success) {
    [NSException raise:@"访问数据库错误" format:@"%@", [error localizedDescription]];
}
// 如果是想做更新操作：只要在更改了实体对象的属性后调用[context save:&error]，就能将更改的数据同步到数据库

初始化一个查询请求
NSFetchRequest *request = [[[NSFetchRequest alloc] init] autorelease];
设置要查询的实体
NSEntityDescription *desc = [NSEntityDescription entityForName:@"Person" inManagedObjectContext:context];
设置排序（按照age降序）
NSSortDescriptor *sort = [NSSortDescriptor sortDescriptorWithKey:@"age" ascending:NO];
request.sortDescriptors = [NSArray arrayWithObject:sort];
设置条件过滤(name like '%Itcast-1%')
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"name like %@", @"*Itcast-1*"];
request.predicate = predicate;

执行请求
NSError *error = nil;
NSArray *objs = [context executeFetchRequest:request error:&error];
if (error) {
    [NSException raise:@"查询错误" format:@"%@", [error localizedDescription]];
}
遍历数据
for (NSManagedObject *obj in objs) {
    NSLog(@"name=%@", [obj valueForKey:@"name"]
}

删除数据

传入需要删除的实体对象
[context deleteObject:managedObject];
将结果同步到数据库
NSError *error = nil;
[context save:&error];
if (error) {
    [NSException raise:@"删除错误" format:@"%@", [error localizedDescription]];
}

打开Core Data的SQL日志输出开关

CoreData的延迟加载

创建NSManagedObject的子类

创建NSManagedObject的子类

创建NSManagedObject的子类

14.ios之数据存取