#pragma mark - NSCoding -(void)encodeWithCoder:(NSCoder *)aCoder { Class currentClass = self.class; if (currentClass == NSObject.class) { return; } while (currentClass && currentClass != [NSObject class]) { unsigned int count = 0; Ivar *ivar = class_copyIvarList(currentClass, &count); if (count>0) { for (int i=0; i 0) { for (int i = 0; i < count; i++) { NSString *key = [NSString stringWithUTF8String:ivar_getName(ivar[i])]; id value = https://www.it610.com/article/[aDecoderdecodeObjectForKey:key]; if (value) { [self setValue:value forKey:key]; } } } currentClass = class_getSuperclass(currentClass); free(ivar); } } returnself; }

#pragma mark - NSCoding -(void)encodeWithCoder:(NSCoder *)aCoder { Class currentClass = self.class; if (currentClass == NSObject.class) { return; } while (currentClass && currentClass != [NSObject class]) { unsigned int count = 0; objc_property_t *pList = class_copyPropertyList(currentClass, &count); if (count>0) { for (int i=0; i 0) { for (int i = 0; i < count; i++) { NSString *key = [NSString stringWithUTF8String:property_getName(pList[i])]; [self setValue:[aDecoderdecodeObjectForKey:key] forKey:key]; } } currentClass = class_getSuperclass(currentClass); free(pList); } returnself; }

• 对象归档是调用NSKeyedArchiver的工厂方法 archiveRootObject: toFile:方法

NSString *file = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).firstObject stringByAppendingPathComponent:@"person.data"]; Person *person = [[Person alloc] init]; person.avatar = self.avatarView.image; person.name = self.nameField.text; person.age = [self.ageField.text integerValue]; [NSKeyedArchiver archiveRootObject:person toFile:file];

• 解档对象就调用NSKeyedUnarchiver的一个工厂方法 unarchiveObjectWithFile:即可

NSString *file = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).firstObject stringByAppendingPathComponent:@"person.data"]; Person *person = [NSKeyedUnarchiver unarchiveObjectWithFile:file]; if (person) { self.avatarView.image = person.avatar; self.nameField.text = person.name; self.ageField.text = [NSString stringWithFormat:@"%ld", person.age]; }

• integer : 整数
  
• real : 实数（浮点数）
  
• text : 文本字符串
  
• blob : 二进制数据，比如文件，图片之类的
  

2. 准备工作

• 创建数据库并打开

/** *打开数据库并创建一个表 */ - (void)openDatabase { //1.设置文件名 NSString *filename = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).firstObject stringByAppendingPathComponent:@"person.db"]; //2.打开数据库文件，如果没有会自动创建一个文件 NSInteger result = sqlite3_open(filename.UTF8String, &_sqlite3); if (result == SQLITE_OK) { NSLog(@"打开数据库成功！"); //3.创建一个数据库表 char *errmsg = NULL; sqlite3_exec(_sqlite3, "CREATE TABLE IF NOT EXISTS t_person(id integer primary key autoincrement, name text, age integer)", NULL, NULL, &errmsg); if (errmsg) { NSLog(@"错误：%s", errmsg); } else { NSLog(@"创表成功！"); } } else { NSLog(@"打开数据库失败！"); } }

• 执行指令

/** *往表中插入1000条数据 */ - (void)insertData { NSString *nameStr; NSInteger age; for (NSInteger i = 0; i < 1000; i++) { nameStr = [NSString stringWithFormat:@"Bourne-%d", arc4random_uniform(10000)]; age = arc4random_uniform(80) + 20; NSString *sql = [NSString stringWithFormat:@"INSERT INTO t_person (name, age) VALUES('%@', '%ld')", nameStr, age]; char *errmsg = NULL; sqlite3_exec(_sqlite3, sql.UTF8String, NULL, NULL, &errmsg); if (errmsg) { NSLog(@"错误：%s", errmsg); } } NSLog(@"插入完毕！"); }

• 查询指令

• sqlite3_prepare_v2() : 检查sql的合法性
  
• sqlite3_step() : 逐行获取查询结果，不断重复，直到最后一条记录
  
• sqlite3_coloum_xxx() : 获取对应类型的内容，iCol对应的就是SQL语句中字段的顺序，从0开始。根据实际查询字段的属性，使用sqlite3_column_xxx取得对应的内容即可。
  
• sqlite3_finalize() : 释放stmt
  

/** *从表中读取数据到数组中 */ - (void)readData { NSMutableArray *mArray = [NSMutableArray arrayWithCapacity:1000]; char *sql = "select name, age from t_person; "; sqlite3_stmt *stmt; NSInteger result = sqlite3_prepare_v2(_sqlite3, sql, -1, &stmt, NULL); if (result == SQLITE_OK) { while (sqlite3_step(stmt) == SQLITE_ROW) { char *name = (char *)sqlite3_column_text(stmt, 0); NSInteger age = sqlite3_column_int(stmt, 1); //创建对象 Person *person = [Person personWithName:[NSString stringWithUTF8String:name] Age:age]; [mArray addObject:person]; } self.dataList = mArray; } sqlite3_finalize(stmt); }

• FMDatabase

• FMResultSet

• FMDatabaseQueue

NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).firstObject stringByAppendingPathComponent:@"person.db"]; FMDatabase *database = [FMDatabase databaseWithPath:path]; if (![database open]) { NSLog(@"数据库打开失败！"); }

• 具体文件路径，如果不存在会自动创建
  
• 空字符串@""，会在临时目录创建一个空的数据库，当FMDatabase连接关闭时，数据库文件也被删除
  
• nil，会创建一个内存中临时数据库，当FMDatabase连接关闭时，数据库会被销毁
  

//常用方法有以下3种： - (BOOL)executeUpdate:(NSString*)sql, ... - (BOOL)executeUpdateWithFormat:(NSString*)format, ... - (BOOL)executeUpdate:(NSString*)sql withArgumentsInArray:(NSArray *)arguments //示例 [database executeUpdate:@"CREATE TABLE IF NOT EXISTS t_person(id integer primary key autoincrement, name text, age integer)"]; //或者 [database executeUpdate:@"INSERT INTO t_person(name, age) VALUES(?, ?)", @"Bourne", [NSNumber numberWithInt:42]];

- (FMResultSet *)executeQuery:(NSString*)sql, ... - (FMResultSet *)executeQueryWithFormat:(NSString*)format, ... - (FMResultSet *)executeQuery:(NSString *)sql withArgumentsInArray:(NSArray *)arguments

//1.执行查询 FMResultSet *result = [database executeQuery:@"SELECT * FROM t_person"]; //2.遍历结果集 while ([result next]) { NSString *name = [result stringForColumn:@"name"]; int age = [result intForColumn:@"age"]; }

• 创建队列。

• 使用队列

[queue inDatabase:^(FMDatabase *database) { [database executeUpdate:@"INSERT INTO t_person(name, age) VALUES (?, ?)", @"Bourne_1", [NSNumber numberWithInt:1]]; [database executeUpdate:@"INSERT INTO t_person(name, age) VALUES (?, ?)", @"Bourne_2", [NSNumber numberWithInt:2]]; [database executeUpdate:@"INSERT INTO t_person(name, age) VALUES (?, ?)", @"Bourne_3", [NSNumber numberWithInt:3]]; FMResultSet *result = [database executeQuery:@"select * from t_person"]; while([result next]) { } }];

[queue inTransaction:^(FMDatabase *database, BOOL *rollback) { [database executeUpdate:@"INSERT INTO t_person(name, age) VALUES (?, ?)", @"Bourne_1", [NSNumber numberWithInt:1]]; [database executeUpdate:@"INSERT INTO t_person(name, age) VALUES (?, ?)", @"Bourne_2", [NSNumber numberWithInt:2]]; [database executeUpdate:@"INSERT INTO t_person(name, age) VALUES (?, ?)", @"Bourne_3", [NSNumber numberWithInt:3]]; FMResultSet *result = [database executeQuery:@"select * from t_person"]; while([result next]) { } //回滚 *rollback = YES; }];

1. CoreData的简单使用

• 创建数据库

• 创建模型文件

- (void)viewDidLoad { [super viewDidLoad]; /* * 关联的时候，如果本地没有数据库文件，Ｃoreadata自己会创建 */// 1. 上下文 NSManagedObjectContext *context = [[NSManagedObjectContext alloc] init]; // 2. 上下文关连数据库// 2.1 model模型文件 NSManagedObjectModel *model = [NSManagedObjectModel mergedModelFromBundles:nil]; // 2.2 持久化存储调度器 // 持久化，把数据保存到一个文件，而不是内存 NSPersistentStoreCoordinator *store = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:model]; // 2.3 设置CoreData数据库的名字和路径 NSString *doc = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject]; NSString *sqlitePath = [doc stringByAppendingPathComponent:@"company.sqlite"]; [store addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:[NSURL fileURLWithPath:sqlitePath] options:nil error:nil]; context.persistentStoreCoordinator = store; _context = context; }

• 添加元素 - Create

-(IBAction)addEmployee{// 创建一个员工对象 //Employee *emp = [[Employee alloc] init]; 不能用此方法创建 Employee *emp = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:_context]; emp.name = @"wangwu"; emp.height = @1.80; emp.birthday = [NSDate date]; // 直接保存数据库 NSError *error = nil; [_context save:&error]; if (error) { NSLog(@"%@",error); } }

• 读取数据 - Read

-(IBAction)readEmployee{// 1.FetchRequest 获取请求对象 NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Employee"]; // 2.设置过滤条件 // 查找zhangsan NSPredicate *pre = [NSPredicate predicateWithFormat:@"name = %@", @"zhangsan"]; request.predicate = pre; // 3.设置排序 // 身高的升序排序 NSSortDescriptor *heigtSort = [NSSortDescriptor sortDescriptorWithKey:@"height" ascending:NO]; request.sortDescriptors = @[heigtSort]; // 4.执行请求 NSError *error = nil; NSArray *emps = [_context executeFetchRequest:request error:&error]; if (error) { NSLog(@"error"); }//NSLog(@"%@",emps); //遍历员工 for (Employee *emp in emps) { NSLog(@"名字 %@ 身高 %@ 生日 %@",emp.name,emp.height,emp.birthday); } }

• 修改数据 - Update

-(IBAction)updateEmployee{ // 改变zhangsan的身高为2m// 1.查找到zhangsan // 1.1FectchRequest 抓取请求对象 NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Employee"]; // 1.2设置过滤条件 // 查找zhangsan NSPredicate *pre = [NSPredicate predicateWithFormat:@"name = %@", @"zhangsan"]; request.predicate = pre; // 1.3执行请求 NSArray *emps = [_context executeFetchRequest:request error:nil]; // 2.更新身高 for (Employee *e in emps) { e.height = @2.0; }// 3.保存 NSError *error = nil; [_context save:&error]; if (error) { NSLog(@"%@",error); } }

• 删除数据 - Delete

-(IBAction)deleteEmployee{// 删除 lisi// 1.查找lisi // 1.1FectchRequest 抓取请求对象 NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Employee"]; // 1.2设置过滤条件 // 查找zhangsan NSPredicate *pre = [NSPredicate predicateWithFormat:@"name = %@", @"lisi"]; request.predicate = pre; // 1.3执行请求 NSArray *emps = [_context executeFetchRequest:request error:nil]; // 2.删除 for (Employee *e in emps) { [_context deleteObject:e]; }// 3.保存 NSError *error = nil; [_context save:&error]; if (error) { NSLog(@"%@",error); }}

2. CoreData的表关联

• 创建数据库

• 创建模型文件

- (void)viewDidLoad { [super viewDidLoad]; /* * 关联的时候，如果本地没有数据库文件，Ｃoreadata自己会创建 */// 1. 上下文 NSManagedObjectContext *context = [[NSManagedObjectContext alloc] init]; // 2. 上下文关连数据库// 2.1 model模型文件 NSManagedObjectModel *model = [NSManagedObjectModel mergedModelFromBundles:nil]; // 2.2 持久化存储调度器 // 持久化，把数据保存到一个文件，而不是内存 NSPersistentStoreCoordinator *store = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:model]; // 2.3 设置CoreData数据库的名字和路径 NSString *doc = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject]; NSString *sqlitePath = [doc stringByAppendingPathComponent:@"company.sqlite"]; [store addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:[NSURL fileURLWithPath:sqlitePath] options:nil error:nil]; context.persistentStoreCoordinator = store; _context = context; }

• 添加元素 - Create

-(IBAction)addEmployee{// 1. 创建两个部门 ios android //1.1 iOS部门 Department *iosDepart = [NSEntityDescription insertNewObjectForEntityForName:@"Department" inManagedObjectContext:_context]; iosDepart.name = @"ios"; iosDepart.departNo = @"0001"; iosDepart.createDate = [NSDate date]; //1.2 Android部门 Department *andrDepart = [NSEntityDescription insertNewObjectForEntityForName:@"Department" inManagedObjectContext:_context]; andrDepart.name = @"android"; andrDepart.departNo = @"0002"; andrDepart.createDate = [NSDate date]; //2. 创建两个员工对象 zhangsan属于ios部门 lisi属于android部门 //2.1 zhangsan Employee *zhangsan = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:_context]; zhangsan.name = @"zhangsan"; zhangsan.height = @(1.90); zhangsan.birthday = [NSDate date]; zhangsan.depart = iosDepart; //2.2 lisi Employee *lisi = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:_context]; lisi.name = @"lisi"; lisi.height = @2.0; lisi.birthday = [NSDate date]; lisi.depart = andrDepart; //3. 保存数据库 NSError *error = nil; [_context save:&error]; if (error) { NSLog(@"%@",error); } }

• 读取信息 - Read

-(IBAction)readEmployee{// 读取ios部门的员工// 1.FectchRequest 抓取请求对象 NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Employee"]; // 2.设置过滤条件 NSPredicate *pre = [NSPredicate predicateWithFormat:@"depart.name = %@",@"android"]; request.predicate = pre; // 4.执行请求 NSError *error = nil; NSArray *emps = [_context executeFetchRequest:request error:&error]; if (error) { NSLog(@"error"); }//遍历员工 for (Employee *emp in emps) { NSLog(@"名字 %@ 部门 %@",emp.name,emp.depart.name); } }

3. CoreData的模糊查询

• 模糊查询

-(IBAction)readEmployee{ // 1.FectchRequest 抓取请求对象 NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Employee"]; // 2.设置排序 // 按照身高的升序排序 NSSortDescriptor *heigtSort = [NSSortDescriptor sortDescriptorWithKey:@"height" ascending:NO]; request.sortDescriptors = @[heigtSort]; // 3.模糊查询 // 3.1 名字以"wang"开头 //NSPredicate *pre = [NSPredicate predicateWithFormat:@"name BEGINSWITH %@",@"wangwu1"]; //request.predicate = pre; // 名字以"1"结尾 //NSPredicate *pre = [NSPredicate predicateWithFormat:@"name ENDSWITH %@",@"1"]; //request.predicate = pre; // 名字包含"wu1" //NSPredicate *pre = [NSPredicate predicateWithFormat:@"name CONTAINS %@",@"wu1"]; //request.predicate = pre; // like 匹配 NSPredicate *pre = [NSPredicate predicateWithFormat:@"name like %@",@"*wu12"]; request.predicate = pre; // 4.执行请求 NSError *error = nil; NSArray *emps = [_context executeFetchRequest:request error:&error]; if (error) { NSLog(@"error"); }//遍历员工 for (Employee *emp in emps) { NSLog(@"名字 %@ 身高 %@ 生日 %@",emp.name,emp.height,emp.birthday); } }

• 分页查询

-(void)pageSeacher{ // 1. FectchRequest 抓取请求对象 NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Employee"]; // 2. 设置排序 // 身高的升序排序 NSSortDescriptor *heigtSort = [NSSortDescriptor sortDescriptorWithKey:@"height" ascending:NO]; request.sortDescriptors = @[heigtSort]; // 3. 分页查询 // 总有共有15数据 // 每次获取6条数据 // 第一页 0,6 // 第二页 6,6 // 第三页 12,6 3条数据// 3.1 分页的起始索引 request.fetchOffset = 12; // 3.2 分页的条数 request.fetchLimit = 6; // 4. 执行请求 NSError *error = nil; NSArray *emps = [_context executeFetchRequest:request error:&error]; if (error) { NSLog(@"error"); }// 5. 遍历员工 for (Employee *emp in emps) { NSLog(@"名字 %@ 身高 %@ 生日 %@",emp.name,emp.height,emp.birthday); } }

4. 多个数据库的使用

• 创建多个数据库，即创建多个DataModel
• 一个数据库对应一个上下文
• 需要根据bundle名创建上下文
• 添加或读取信息，需要根据不同的上下文，访问不同的实体
• 关联数据库和实体

- (void)viewDidLoad { [super viewDidLoad]; // 一个数据库对应一个上下文 _companyContext = [self setupContextWithModelName:@"Company"]; _weiboContext = [self setupContextWithModelName:@"Weibo"]; }/** *根据模型文件，返回一个上下文 */ -(NSManagedObjectContext *)setupContextWithModelName:(NSString *)modelName{// 1. 上下文 NSManagedObjectContext *context = [[NSManagedObjectContext alloc] init]; // 2. 上下文关连数据库 // 2.1 model模型文件// 注意：如果使用下面的方法，如果 bundles为nil 会把bundles里面的所有模型文件的表放在一个数据库 //NSManagedObjectModel *model = [NSManagedObjectModel mergedModelFromBundles:nil]; // 改为以下的方法获取： NSURL *companyURL = [[NSBundle mainBundle] URLForResource:modelName withExtension:@"momd"]; NSManagedObjectModel *model = [[NSManagedObjectModel alloc] initWithContentsOfURL:companyURL]; // 2.2 持久化存储调度器 // 持久化，把数据保存到一个文件，而不是内存 NSPersistentStoreCoordinator *store = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:model]; // 2.3 告诉Coredata数据库的名字和路径 NSString *doc = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject]; NSString *sqliteName = [NSString stringWithFormat:@"%@.sqlite",modelName]; NSString *sqlitePath = [doc stringByAppendingPathComponent:sqliteName]; [store addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:[NSURL fileURLWithPath:sqlitePath] options:nil error:nil]; context.persistentStoreCoordinator = store; // 3. 返回上下文 return context; }

• 添加元素

-(IBAction)addEmployee{ // 1. 添加员工 Employee *emp = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:_companyContext]; emp.name = @"zhagsan"; emp.height = @2.3; emp.birthday = [NSDate date]; // 直接保存数据库 [_companyContext save:nil]; // 2. 发微博 Status *status =[NSEntityDescription insertNewObjectForEntityForName:@"Status" inManagedObjectContext:_weiboContext]; status.text = @"发了一条微博！"; status.createDate = [NSDate date]; [_weiboContext save:nil]; }

推荐阅读

• 

  椰子油的生活小妙用 椰子油有什么用途和功效
• 

  庆东锅炉故障代码是什么如何解决
• 

  教学教务管理人员是干什么的
• 

  联想yoga2
• 

  如何选择抗体稀释液？ 抗体稀释液
• 

  下载导航地图，导航地图下载
• 

  流媒体后视镜可以当行车记录仪吗 行车记录仪有必要买流媒体吗
• 

  炒苔菜用不用焯水，苔菜用不用焯水再炒
• 

  昆明工业职业技术学院怎么样
• 

  （152）感赏女儿|（152）感赏女儿 2020-12-4
• 

  桃子核发霉外面是好的还能吃吗
• 

  离散傅立叶分析,origin怎么进行傅立叶分析
• 

  次密接触者的一般接触者需要隔离吗
• 

  海带炖土豆的做法 海带炖土豆的做法窍门
• 

  大概的近义词 大概的近义词是什么 标准答案
• 

  合金筷子是塑料还是金属 合金筷子是什么材质
• 

  真我与假我
• 

  钢材包括哪些 钢材怎么分类
• 

  heos,黑色素瘤
• 

  【家事】节如流水

• Docker应用:容器间通信与Mariadb数据库主从复制
• 使用协程爬取网页，计算网页数据大小
• Java|Java基础——数组
• Python数据分析(一)（Matplotlib使用）
• Jsr303做前端数据校验
• Spark|Spark 数据倾斜及其解决方案
• 数据库设计与优化
• 爬虫数据处理HTML转义字符
• 数据库总结语句
• MySql数据库备份与恢复