IOS开发数据库篇-概要

    // NSUserDefaults 默认
    NSUserDefaults *userDefaults =  [NSUserDefaults standardUserDefaults];
    [userDefaults setObject:@"skyming" forKey:@"username"];
    [userDefaults setObject:[NSDate date] forKey:@"date"];
    [userDefaults setObject:@[@"a1",@"a2"] forKey:@"array"];
    [userDefaults setInteger:6174 forKey:@"code"];
    NSLog(@"userDefaults: %@",[userDefaults dictionaryRepresentation]);
    
    NSString *username = [userDefaults objectForKey:@"username"];
    NSDate *date = [userDefaults objectForKey:@"date"];
    NSArray *array = [userDefaults objectForKey:@"array"];
    NSInteger code = [userDefaults integerForKey:@"code"];
    
    NSLog(@"username: %@  date:%@  
 array: %@ code: %d", username, date, array, code);
    [userDefaults synchronize];
    // NSUserDefaults 自定义
    NSUserDefaults *defaults = [[NSUserDefaults alloc] init];
    [defaults setPersistentDomain:[NSDictionary dictionaryWithObject:@"Hello" forKey:@"World"] forName:@"com.Sensoro.DefaultsTest"];
    [defaults synchronize];

//  数组
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);  
    NSString *docPath = [paths objectAtIndex:0];  
    NSString *myFile = [docPath stringByAppendingPathComponent:@"my.list"];  
    //读取文件  
    NSArray *array = [[NSArray alloc] initWithContentsOfFile:myFile];  
    //操作完若修改了数据则，写入文件  
    [array writeToFile:myFile atomically:YES];  

 #pragma mark -
#pragma NSCoding协议实现实现
- (void)encodeWithCoder:(NSCoder *)aCoder
{   //encoder
    [aCoder encodeObject:self.username forKey:@"username"];
    [aCoder encodeObject:self.password forKey:@"password"];
}
- (id)initWithCoder:(NSCoder *)aDecoder
{
    //decoder
    if (self = [super init]) {
        self.username = [aDecoder decodeObjectForKey:@"username"];
        self.password =  [aDecoder decodeObjectForKey:@"password"];
    }
    return self;
}

#pragma NSCopying协议实现
- (id)copyWithZone:(NSZone *)zone
{
    DSObj *copy = [[[self class] allocWithZone:zone] init];
    return copy;
}

// 读取    
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *docPath = [paths objectAtIndex:0];
    NSString *myFile = [docPath stringByAppendingPathComponent:@"dsObj.list"];
    
    //写入归档文件
    NSMutableData *datawrite = [[NSMutableData alloc] init];
    NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:datawrite];
    [archiver encodeObject:test forKey:@"data"];
    [archiver finishEncoding];
    [datawrite writeToFile:myFile atomically:YES];
    
    //读取归档文件
    NSData *data = [[NSMutableData alloc] initWithContentsOfFile:myFile];
    NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data];
    DSObj *testread = [unarchiver decodeObjectForKey:@"data"];
    [unarchiver finishDecoding];
    NSLog(@"DSObjRead: %@ %@",[testread username], [testread password]);

//open database
- (void)openDataBase
{
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *docPath = [paths objectAtIndex:0];
    NSString *myFile = [docPath stringByAppendingPathComponent:@"data.db"];
    
    if (sqlite3_open([myFile UTF8String], &database)==SQLITE_OK)
    {
        NSLog(@"open sqlite db ok.");
    }
    else
    {
        NSLog( @"can not open sqlite db " );
        
        //close database
        sqlite3_close(database);
    }
}

//create table
- (void)createTable
{
    char *errorMsg;
    const char *createSql="create table if not exists persons (id integer primary key autoincrement,name text)";
    
    if (sqlite3_exec(database, createSql, NULL, NULL, &errorMsg)==SQLITE_OK)
    {
        NSLog(@"create ok.");
    }
    else
    {
        NSLog( @"can not create table" );
        [self ErrorReport:[NSString stringWithFormat:@"%s",createSql]];
    }
}


//insert table
- (void)insertTable
{
    char *errorMsg;
    
    const char *insertSql="insert into persons (name) values ('skyming')";
    if (sqlite3_exec(database, insertSql, NULL, NULL, &errorMsg)==SQLITE_OK)
    {
        NSLog(@"insert ok.");
    }
    else
    {
        NSLog( @"can not insert it to table" );
        [self ErrorReport:[NSString stringWithFormat:@"%s",insertSql]];
    }
}

//query table
- (void)queryTable
{
    const char *selectSql="select id,name from persons";
    sqlite3_stmt *statement;
    if (sqlite3_prepare_v2(database, selectSql, -1, &statement, nil)==SQLITE_OK)
    {
        NSLog(@"select ok.");
        while (sqlite3_step(statement)==SQLITE_ROW)//SQLITE_OK SQLITE_ROW
        {
            int _id=sqlite3_column_int(statement, 0);
            NSString *name=[[NSString alloc] initWithCString:(char *)sqlite3_column_text(statement, 1) encoding:NSUTF8StringEncoding];
            NSLog(@"row>>id %i, name>> %@",_id,name);
        }
        
    }
    else
    {
        //error
        [self ErrorReport:[NSString stringWithFormat:@"%s",selectSql]];
    }
    
    sqlite3_finalize(statement);
}

//delete table
- (void)deleteTable
{
    char *errorMsg;
    [self openDataBase];
    
    const char *sql = "DELETE FROM persons where id=24";
    if (sqlite3_exec(database, sql, NULL, NULL, &errorMsg)==SQLITE_OK)
    {
        NSLog(@"delete ok.");
    }
    else
    {
        NSLog( @"can not delete it" );
        [self ErrorReport:[NSString stringWithFormat:@"%s",sql]];
    }
    
}
//error
- (void)ErrorReport: (NSString *)item
{
    char *errorMsg;
    
    if (sqlite3_exec(database, [item cStringUsingEncoding:NSUTF8StringEncoding], NULL, NULL, &errorMsg)==SQLITE_OK)
    {
        NSLog(@"%@ ok.",item);
    }
    else
    {
        NSLog(@"error: %s",errorMsg);
        sqlite3_free(errorMsg);
    }
}