IOS 数据库

系统自带可以储存字段的字典：

NSUserDefaults *user = [[NSUserDefaults alloc] init];

存 : [user setObject:@"YES" forKey:@"token"];

　取：NSString* string=[user objectForKey:@"token"];

FMdb第三方使用   使用前导入第三方框架外还需要导入libsqlite3包
//创建模型
#import <Foundation/Foundation.h>

@interface LoadModel : NSObject
@property (nonatomic,retain) NSString * username;
@property (nonatomic,retain) NSString * password;
@end

#import "DataCenter.h"
#import "FMDatabase.h"
@implementation DataCenter
{
    FMDatabase *_dataBase;
}
+(id)shareDataCenter{
    static DataCenter *center = nil;
    if(center == nil){
        center = [[DataCenter alloc] init];
    }
    return center;
}
-(id)init{
    self = [super init];
    if(self){
        [self createDB];
    }
    return self;
}
-(void)createDB{
    NSArray *array = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *dbPath = [array[] stringByAppendingPathComponent:@"CB.db"];
    NSLog(@"数据库地址：%@",dbPath);
    _dataBase = [[FMDatabase alloc] initWithPath:dbPath];
    [_dataBase open];

    //用户登录
    [self createUserLoadTable];

}

//创建表    表名 CBUser  列： username  password
-(void)createUserLoadTable{
    NSString *sql = @"create table if not exists CBUser (ID integer primary key autoincrement,username text,password text);";
        BOOL b = [_dataBase executeUpdate:sql];
        if(!b){
            NSLog(@"登录表创建失败");
        }
}

//储存数据 账号  密码
-(void)insertDataWithModel:(LoadModel *)model{
    NSString *sql = @"insert into CBUser (username,password) values (?,?)";
        BOOL b = [_dataBase executeUpdate:sql,model.username,model.password];
        if(!b){
            NSLog(@"等录数据加失败");
        }
}
//查找数据
-(LoadModel *)selectDataWithModel:(NSString *)username{
    NSString *sql = @"select * from CBUser where username = ?";
        FMResultSet *set = [_dataBase executeQuery:sql,username];
    LoadModel *model = [[LoadModel alloc] init];
        while (set.next) {
            //取出名字和密码
            model.username = [set stringForColumn:@"username"];
            model.password = [set stringForColumn:@"password"];
        }
        return model;
}
-(BOOL)selectDataBoolWithNum:(NSString *)username{
    NSString *sql = @"select * from CBUser where username = ?";
    FMResultSet *set = [_dataBase executeQuery:sql,username];
    while (set.next) {
        return YES;
    }
    return NO;
}
//删除表
-(void)deleteAllData{
    NSString *sql = @"delete from CBUser";
    [_dataBase executeUpdate:sql];
}
//获取全部数据
-(NSArray *)selectAllData{
    NSString *sql = @"select * from CBUser";
    FMResultSet *set = [_dataBase executeQuery:sql];
    NSMutableArray *array = [[NSMutableArray alloc] init];
    while (set.next) {
        LoadModel *model = [[LoadModel alloc] init];
        model.username = [set stringForColumn:@"username"];
        model.password = [set stringForColumn:@"password"];
        [array addObject:model];
    }
    return array;
}
//删除某一个数据
-(void)deleteDataWithName:(NSString *)username{
    NSString *sql = @"delete from CBUser where username = ?";
    [_dataBase executeUpdate:sql,username];
}

@end

//调用
   DataCenter* _center=[DataCenter new];
    LoadModel* model=[[LoadModel alloc]init];
    model.username=@"";
    model.password=@"";
    [_center insertDataWithModel:model];