在iOS開發中，除了UI頁面以外使用最多的估計是資料物件的儲存了~比如聊天記錄、通訊錄和通訊記錄、瀏覽記錄等等。我們要根據不同的使用方式去對這些資料儲存並使用。常用的有：①沙盒機制 ②屬性列表plist ③SQLite ④CoreData，本文介紹的就是基礎的SQLite的儲存機制，其他的稍後會陸續跟進~

一、首先要注意SQLite的特性：無資料型別的資料庫，所以和在別的平臺上的SQL會有一定的差距

二、常用資料型別

· integer有符號的整數型別

· text字串型別

· real浮點型別

· blob二進位制物件型別

三、在專案中建立資料庫

①在專案中引入sql支援庫：libsqlite3.tbd，還有一個3.0的，我個人用3，不要問我為什麼啊(╯‵□′)╯︵┻━┻

②配置資料庫，建立兩個NSObject類，一個作為model 一個作為資料庫操作

假設我們只儲存兩個資料，一個是又textview寫入的文字，一個是當前時間

DataModel.h檔案
#import <Foundation/Foundation.h>

@interface DataModel : NSObject

// 用來接收文字的屬性
@property (nonatomic , copy)NSString * text;
// 文字儲存時間
@property (nonatomic , strong)NSDate * date;

// 文字初始化
-(id)initWithText:(NSString *)text Date:(NSDate*)date;

@end

DataModel.m檔案
#import "DataModel.h"

@implementation DataModel

-(id)initWithText:(NSString *)text Date:(NSDate*)date{
    self = [super init];
    if (self) {
        self.text = text;
        self.date = date;
    }
    return self;
}

@end
 

DBOperation.h檔案
#import <Foundation/Foundation.h>
// 引入model
#import "DataModel.h"
// 引入sql的支援庫
#import "sqlite3.h"

// 資料庫檔名
#define DB_Name @"Database.sqlite3"

@interface DBOperation : NSObject
{
    // 資料庫物件的成員變數
    sqlite3 * database;
}

// 建立一個管理器
+ (DBOperation *)DataBaseManager;
// 資料庫檔案路徑
- (NSString *)Documentsfilepath;
// 開啟資料庫、建立資料庫表
- (void)createDataBaseTable;

// 新增
-(int)addData:(DataModel*)model;
// 刪除
-(int)deleteData:(DataModel*)model;
// 修改
-(int)editData:(DataModel*)model;
// 查詢
-(NSMutableArray*)selectall;

@end

DBOperation.m檔案
#import "DBOperation.h"

@implementation DBOperation

// 建立一個靜態變數
static DBOperation * DataBaseManager = nil;

+ (DBOperation*)DataBaseManager
{
    static dispatch_once_t once;
    dispatch_once(&once, ^{
        
        DataBaseManager = [[self alloc] init];
        [DataBaseManager createDataBaseTable];
        
    });
    return DataBaseManager;
}

// 建立一個數據庫，建立名為Text的表設定一個content的屬性
- (void)createDataBaseTable {
    NSString *writableDBPath = [self Documentsfilepath];
    const char* charpath = [writableDBPath UTF8String];
    
    if (sqlite3_open(charpath, &database) != SQLITE_OK) {
        sqlite3_close(database);
        NSAssert(NO,@"資料庫開啟失敗");
    } else {
        char *err;
        // 建立一個數據庫表，名為 Text  並新增兩個元素 其中textdate為主鍵
        NSString *sql = [NSString stringWithFormat:@"CREATE TABLE IF NOT EXISTS Text (textdate TEXT PRIMARY KEY, content TEXT);"];
        const char* charSql = [sql UTF8String];
        
        if (sqlite3_exec(database, charSql,NULL,NULL,&err) != SQLITE_OK) {
            sqlite3_close(database);
            NSAssert(NO, @"建表失敗");
        }
        sqlite3_close(database);
    }
}

// 資料庫存放路徑
- (NSString *)Documentsfilepath {
    NSString *documentDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
    NSString *path = [documentDirectory stringByAppendingPathComponent:DB_Name];
    
    return path;
}

//新增方法
-(int)addData:(DataModel *)model
{
    
    NSString *path = [self Documentsfilepath];
    const char* charpath = [path UTF8String];
    
    if (sqlite3_open(charpath, &database) != SQLITE_OK) {
        sqlite3_close(database);
        NSAssert(NO,@"資料庫開啟失敗。");
    } else {
        
        NSString *sql = @"INSERT OR REPLACE INTO Text (textdate, content) VALUES (?,?)";
        const char* charSql = [sql UTF8String];
        
        sqlite3_stmt *statement;
        //預處理過程
        if (sqlite3_prepare_v2(database, charSql, -1, &statement, NULL) == SQLITE_OK) {
            
            NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
            [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
            NSString *strDate = [dateFormatter stringFromDate:model.date];
            const char* charDate  = [strDate UTF8String];
            
            const char* charContent = [model.text UTF8String];
            
            //繫結引數開始
            sqlite3_bind_text(statement, 1, charDate, -1, NULL);
            sqlite3_bind_text(statement, 2, charContent, -1, NULL);
            
            //執行插入
            if (sqlite3_step(statement) != SQLITE_DONE) {
                NSAssert(NO, @"插入資料失敗。");
            }
        }
        sqlite3_finalize(statement);
        sqlite3_close(database);
    }
    return 0;
}

//刪除方法
-(int)deleteData:(DataModel *)model
{
    NSString *path = [self Documentsfilepath];
    const char* charpath = [path UTF8String];
    
    if (sqlite3_open(charpath, &database) != SQLITE_OK) {
        sqlite3_close(database);
        NSAssert(NO,@"資料庫開啟失敗。");
    } else {
        NSString *sql = @"DELETE from Text where textdate =?";
        const char* charSql = [sql UTF8String];
        
        sqlite3_stmt *statement;
        //預處理過程
        if (sqlite3_prepare_v2(database, charSql, -1, &statement, NULL) == SQLITE_OK) {
            NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
            [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
            NSString *strDate = [dateFormatter stringFromDate:model.date];
            const char * charDate  = [strDate UTF8String];
            
            //繫結引數開始
            sqlite3_bind_text(statement, 1, charDate, -1, NULL);
            //執行
            if (sqlite3_step(statement) != SQLITE_DONE) {
                NSAssert(NO, @"刪除資料失敗。");
            }
        }
        
        sqlite3_finalize(statement);
        sqlite3_close(database);
    }
    
    return 0;
}

//查詢資料方法
-(NSMutableArray*)selectall
{
    NSMutableArray *listData = [[NSMutableArray alloc] init];
    
    NSString *path = [self Documentsfilepath];
    const char* charpath = [path UTF8String];
    
    if (sqlite3_open(charpath, &database) != SQLITE_OK) {
        sqlite3_close(database);
        NSAssert(NO,@"資料庫開啟失敗。");
    } else {
        
        NSString *sql 
 
[email protected]"SELECT textdate,content FROM Text";
        const char* charSql = [sql UTF8String];
        
        sqlite3_stmt *statement;
        //預處理過程
        if (sqlite3_prepare_v2(database, charSql, -1, &statement, NULL) == SQLITE_OK) {
            
            NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
            [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
            
            //執行
            while (sqlite3_step(statement) == SQLITE_ROW) {
                char *bufDate = (char *) sqlite3_column_text(statement, 0);
                NSString *strDate = [[NSString alloc] initWithUTF8String: bufDate];
                NSDate *date = [dateFormatter dateFromString:strDate];
                
                char *bufContent = (char *) sqlite3_column_text(statement, 1);
                NSString * strContent = [[NSString alloc] initWithUTF8String: bufContent];
                
                DataModel * model = [[DataModel alloc] initWithText:strContent Date:date];
                
                [listData addObject:model];
            }
        }
        
        sqlite3_finalize(statement);
        sqlite3_close(database);
        
    }
    return listData;
}

@end

到目前為止資料庫的處理就是基本完成了，剩下的就是去專案裡面開始實際操作，為了方便寫了一個DBManager用來管理引用資料庫操作和model值得傳遞

DBManager.h檔案
#import <Foundation/Foundation.h>
#import "DataModel.h"
#import "DBOperation.h"

@interface DBManager : NSObject

// 新增
-(NSMutableArray *)addTextdata:(DataModel*)model;
// 刪除
-(NSMutableArray *)deleteTextdata:(DataModel*)model;
// 查詢
-(NSMutableArray *)selectall;

@end

DBManager.m檔案
#import "DBManager.h"
@implementation DBManager

// 這個類是用來作為媒介，可用可不用，只是為了讓過程更加清晰

// 新增
-(NSMutableArray *)addTextdata:(DataModel *)model
{
    DBOperation * m = [DBOperation DataBaseManager];
    [m addData:model];
    return [m selectall];
}
// 刪除
-(NSMutableArray *)deleteTextdata:(DataModel *)model
{
    DBOperation * m = [DBOperation DataBaseManager];
    [m deleteData:model];
    return [m selectall];
}

// 查詢
-(NSMutableArray *)selectall
{
    DBOperation * m = [DBOperation DataBaseManager];
    return [m selectall];
}

@end

- (void)viewDidLoad {
    [super viewDidLoad];
    
    self.view.backgroundColor = [UIColor whiteColor];
    
    UIButton * addbtn = [[UIButton alloc]initWithFrame:CGRectMake(self.view.frame.size.width/2, 100, 120, 30)];
    addbtn.backgroundColor = [UIColor redColor];
    [addbtn setTitle:@"新增" forState:UIControlStateNormal];
    [addbtn addTarget:self action:@selector(add) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:addbtn];
    
    textview = [[UITextView alloc]initWithFrame:CGRectMake(0, 150, self.view.frame.size.width, 100)];
    textview.backgroundColor = [UIColor blueColor];
    [self.view addSubview:textview];
    // Do any additional setup after loading the view.
}

-(void)add{
    
    DBManager *manager = [[DBManager alloc] init];
    DataModel *model = [[DataModel alloc] init];
    model.date = [[NSDate alloc] init];
    model.text = textview.text;
    NSMutableArray *reslist = [manager addTextdata: model];
    
    [[NSNotificationCenter defaultCenter] postNotificationName:@"backaction" object:reslist userInfo:nil];
    [self dismissViewControllerAnimated:NO completion:nil];
}

[[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(reloadView:)
                                                 name:@"backaction"
                                               object:nil];

// 向左滑動可刪除資料
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
    if (editingStyle == UITableViewCellEditingStyleDelete) {
        
        DataModel * model = [self.listData objectAtIndex:[indexPath row]];
        DBManager * dm = [[DBManager alloc] init];
        self.listData = [dm deleteTextdata: model];
        [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
        
    }
}

四、也許有人會問我為什麼增刪改查沒有“改”這一項，我想說我也不知道啊，如果知道的教教我~哈哈，正常來說都是網路請求的資料儲存到本地做查詢和刪除，修改資料都是直接上傳到伺服器上面。表示沒有做過需要在本地修改的資料庫專案~(╯‵□′)╯︵┻━┻（我是菜雞）

附上傳送門：demo