SQLite的使用——OC代码

一、添加”libsqlite3.dylib”库文件

二、代码结构

三、代码实现

#import "AppDelegate.h"
#import "SQLiteManager.h"

@interface AppDelegate ()

@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

BOOL flag = [[SQLiteManager shareInstance] openDB];
if (flag) {
NSLog(@"打开数据库成功");
} else {
NSLog(@"打开数据库失败");
}

return YES;
}
@end

#import "ViewController.h"
#import "SQLiteManager.h"
#import "Student.h"

@interface ViewController () <UISearchBarDelegate>

/* 关键字搜索出来的数据 */
@property (nonatomic, strong) NSArray *listData;

@end

@implementation ViewController

/*
0.封装一个工具类,管理SQLite的数据库(单例)
1.创建数据库(文件)
2.创建表,用于存储数据
3.基本操作(增删改)
4.查询数据
*/

- (void)viewDidLoad {
[super viewDidLoad];

// 添加搜索框
UISearchBar *searchBar = [[UISearchBar alloc] init];
searchBar.frame = CGRectMake(0, 0, self.view.bounds.size.width, 44);
self.tableView.tableHeaderView = searchBar;
searchBar.delegate = self;
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
NSArray *students = [Student loadData];
NSLog(@"%@", students);
}

- (void)deleteData
{
// 1.删除的SQL
NSString *deleteSQL = @"DELETE FROM t_student WHERE age = 24;";

// 2.执行SQL
if ([[SQLiteManager shareInstance] execSQL:deleteSQL]) {
NSLog(@"删除数据成功");
}
}

- (void)updateData
{
// 1.更新的SQL
NSString *updateSQL = @"UPDATE t_student SET name = 'zs2' WHERE id = 1;";

// 2.执行sql
if ([[SQLiteManager shareInstance] execSQL:updateSQL]) {
NSLog(@"更新数据成功");
}
}

#pragma mark - 实现UISearchBar的代理方法
- (void)searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText
{
// 1.拿到关键字,查询学生数据
self.listData = [Student loadDataWithKeyword:searchText];

// 2.刷新表格
[self.tableView reloadData];
}

#pragma mark - 实现tableView的数据源方法
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return self.listData.count;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *ID = @"MenuCell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:ID];

if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:ID];
}

Student *stu = self.listData[indexPath.row];
cell.textLabel.text = stu.name;

return cell;
}

@end

#import <Foundation/Foundation.h>

@interface SQLiteManager : NSObject

+ (instancetype)shareInstance;

- (BOOL)openDB;

- (BOOL)execSQL:(NSString *)sql;

- (NSArray *)querySQL:(NSString *)querySQL;

@end

#import "SQLiteManager.h"
#import <sqlite3.h>

@interface SQLiteManager ()

@property (nonatomic, assign) sqlite3 *db;

@end

@implementation SQLiteManager

static id _instance;

+ (instancetype)shareInstance
{
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
_instance = [[self alloc] init];
});

return _instance;
}

#pragma mark - 创建或者打开数据库
- (BOOL)openDB
{
// 获取沙盒路径,将数据库放入沙盒中
NSString *filePath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
filePath = [filePath stringByAppendingPathComponent:@"my.sqlite"];

// 如果有对应的数据库,则打开对应的数据库.如果没有对应的数据库,则创建数据库
// 1> 参数一:文件路径(数据库的存放路径)
// 2> 参数二:操作数据库的对象
if (sqlite3_open(filePath.UTF8String, &_db) != SQLITE_OK) {
NSLog(@"打开数据库失败");
return NO;
}

// 如果打开数据成功,则创建一张表,用于之前存放数据
return [self createTable];
}

- (BOOL)createTable {
// 1.定义创建表的SQL语句
NSString *createTableSQL = @"CREATE TABLE IF NOT EXISTS 't_student' ('id' INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,'name' TEXT,'age' INTEGER);";

// 2.执行SQL语句
return [self execSQL:createTableSQL];
}

- (BOOL)execSQL:(NSString *)sql
{
// 执行sql语句
// 1> 参数一:数据库sqlite3对象
// 2> 参数二:执行的sql语句
return sqlite3_exec(self.db, sql.UTF8String, nil, nil, nil) == SQLITE_OK;
}

#pragma mark - 查询数据
- (NSArray *)querySQL:(NSString *)querySQL
{
// 定义游标对象
sqlite3_stmt *stmt = nil;

// 准备工作(获取查询的游标对象)
// 1> 参数三:查询语句的长度, -1自动计算
// 2> 参数四:查询的游标对象地址
if (sqlite3_prepare_v2(self.db, querySQL.UTF8String, -1, &stmt, nil) != SQLITE_OK) {
NSLog(@"没有准备成功");
return nil;
}

// 取出某一个行数的数据
NSMutableArray *tempArray = [NSMutableArray array];
// 获取字段的个数
int count = sqlite3_column_count(stmt);
while (sqlite3_step(stmt) == SQLITE_ROW) {
NSMutableDictionary *dict = [NSMutableDictionary dictionary];
for (int i = 0; i < count; i++) {
// 1.取出当前字段的名称(key)
NSString *key = [NSString stringWithUTF8String:sqlite3_column_name(stmt, i)];

// 2.取出当前字段对应的值(value)
const char *cValue = (const char *)sqlite3_column_text(stmt, i);
NSString *value = [NSString stringWithUTF8String:cValue];

// 3.将键值对放入字典中
[dict setObject:value forKey:key];
}

[tempArray addObject:dict];
}

// 不再使用游标时,需要释放对象
sqlite3_finalize(stmt);

return tempArray;
}

@end

#import <Foundation/Foundation.h>

@interface Student : NSObject

@property (nonatomic, copy) NSString *name;
@property (nonatomic, assign) NSInteger age;

- (instancetype)initWithDict:(NSDictionary *)dict;

- (void)insertStudent;

+ (NSArray *)loadData;

+ (NSArray *)loadDataWithKeyword:(NSString *)keyword;

@end

#import "Student.h"
#import "SQLiteManager.h"

@implementation Student

- (instancetype)initWithDict:(NSDictionary *)dict
{
if (self = [super init]) {
[self setValuesForKeysWithDictionary:dict];
}
return self;
}

- (void)insertStudent
{
// 1.通过属性拼接出来,插入语句
NSString *insertSQL = [NSString stringWithFormat:@"INSERT INTO t_student (name, age) VALUES ('%@', %ld);", self.name, self.age];

// 2.执行该sql语句
if ([[SQLiteManager shareInstance] execSQL:insertSQL]) {
NSLog(@"插入数据成功");
}
}

+ (NSArray *)loadData
{
// 1.封装查询语句
NSString *querySQL = @"SELECT name, age FROM t_student;";

return [self loadDataWithQuerySQL:querySQL];
}

+ (NSArray *)loadDataWithKeyword:(NSString *)keyword
{
// 1.封装查询语句
NSString *querySQL = [NSString stringWithFormat:@"SELECT name, age FROM t_student WHERE name like '%%%@%%';", keyword];

return [self loadDataWithQuerySQL:querySQL];
}

+ (NSArray *)loadDataWithQuerySQL:(NSString *)querySQL
{
// 2.执行查询语句
NSArray *dictArray = [[SQLiteManager shareInstance] querySQL:querySQL];

// 3.将数组中的字典转成模型对象
NSMutableArray *stus = [NSMutableArray array];
for (NSDictionary *dict in dictArray) {
[stus addObject:[[Student alloc] initWithDict:dict]];
}

return stus;
}

@end