早期笔记——数据库工具类

总结：对于数据库才做应该独立到一个类，而且要去单例模式。

#import "DBManager.h"
#import "FMDatabase.h"
#import "LimitFreeModel.h"

static DBManager * m_DBManger;

@interface DBManager ()

@property (nonatomic,strong)FMDatabase * db;

@end

@implementation DBManager

//单例
+(DBManager *)sharedDBManager
{
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        m_DBManger = [[DBManager alloc] init];
    });//采取了更为准确的单例模式
    return m_DBManger;
}
- (id)init
{
    if (self = [super init]) {
        NSString * dbPath = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/db.sqlite"];
        self.db =[FMDatabase databaseWithPath:dbPath];
        if (![self.db open]) {
            NSLog(@"打开数据库失败");
        }
        //创建表
        NSString * sql = @"create table if not exists t_favourite(id INTEGER PRIMARY KEY autoincrement,applicationID text UNIQUE,appname text)";

        [self.db executeUpdate:sql];
    }
    return self;
}
//增
- (void)addFavorite:(LimitFreeModel *)model
{
    NSString * sql = @"INSERT INTO t_favourite(applicationID,appname) values (?,?)";
    [self.db executeUpdate:sql,model.applicationId,model.name];
}
//删
- (void)removefavorite:(LimitFreeModel *)model
{
    NSString * sql = @"DELETE FROM t_favourite where applicationID = ?";

    [self.db executeUpdate:sql,model.applicationId];

}
//判断是否已经存储过
- (BOOL)isExistFavorite:(LimitFreeModel *)model
{
    NSString * sql = @"SELECT * FROM t_favourite WHERE applicationID = ?";

    FMResultSet * result = [self.db executeQuery:sql,model.applicationId];
    while ([result next]) {
        return YES;
    }
    return NO;
}
//查询
- (NSArray *)getAllFavorites
{
    NSString * sql = @"SELECT * FROM t_favourite";

    FMResultSet * result = [self.db executeQuery:sql];
    NSMutableArray * resultArray = [NSMutableArray new];
    while ([result next]) {
        LimitFreeModel * model = [[LimitFreeModel alloc] init];
        model.applicationId = [result stringForColumn:@"applicationID"];
        model.name = [result stringForColumn:@"appname"];
        [resultArray addObject:model];
    }
    return resultArray;
}


//7，更新数据（改）
-(void)updateUserData:(NSString *)updateName replaceName:(NSString *)replaceName{
    NSString * sql = @"update User set name = ? where name = ?";
    BOOL isOK = [dataBase executeUpdate:sql,replaceName,updateName];
    if (isOK) {
        NSLog(@"更新成功");
    }else{
        NSLog(@"更新失败");
    }
}

二、调用单例解决问题

    if ([[DBManager sharedDBManager] isExistFavorite:self.model]) {

        [[DBManager sharedDBManager] removefavorite:self.model];

        [self.favoriteBtn setTitle:@"收藏" forState:UIControlStateNormal];

    }
    else{
        [[DBManager sharedDBManager]addFavorite:self.model];
        [self.favoriteBtn setTitle:@"取消收藏" forState:UIControlStateNormal];
    }