iOS 开发指南 第11章 数据持久化之属性列表 学习

- (NSString *)applicationDocumentsDirectoryFile {获取沙箱Documents目录文件的完整路径
    NSString *documentDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
    NSString *path = [documentDirectory stringByAppendingPathComponent:@"NotesList.plist"];

    return path;
}
- (void)createEditableCopyOfDatabaseIfNeeded {
    
    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSString *writableDBPath = [self applicationDocumentsDirectoryFile];获取文件目录
    判断文件是否存在：fileExistsAtPath：
    BOOL dbexits = [fileManager fileExistsAtPath:writableDBPath];
    if (!dbexits) {若不存在则复制一个
        NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"NotesList.plist"];
        
        NSError *error;
        BOOL success = [fileManager copyItemAtPath:defaultDBPath toPath:writableDBPath error:&error];
        NSAssert(success, @"错误写入文件");断言函数，第一个参数为假时抛出异常
    }
}

//插入Note方法
-(int) create:(Note*)model
{
    NSString *path = [self applicationDocumentsDirectoryFile];
    NSMutableArray *array = [[NSMutableArray alloc] initWithContentsOfFile:path];
    
    NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
    [dateFormat setDateFormat: @"yyyy-MM-dd HH:mm:ss"];
    将传入的数据封装成文件所需格式
    NSDictionary* dict = [NSDictionary
                          dictionaryWithObjects:@[[dateFormat stringFromDate: model.date],model.content]
                          forKeys:@[@"date",@"content"]];
    ＊
setValue：forKey：
    ＊
    [array addObject:dict];

    [array writeToFile:path atomically:YES];
    
    return 0;
}

//删除Note方法
-(int) remove:(Note*)model
{
    NSString *path = [self applicationDocumentsDirectoryFile];
    NSMutableArray *array = [[NSMutableArray alloc] initWithContentsOfFile:path];
    
    for (NSDictionary* dict in array) {
        
        NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
        [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
        是把value取出来而不是key比较
        //Note* note = [[Note alloc] init];
        NSDate *date = [dateFormatter dateFromString:[dict objectForKey:@"date"]];
        //note.content = [dict objectForKey:@"content"];
        
        //比较日期主键是否相等
        if ([date isEqualToDate:model.date]){
            [array removeObject: dict];
            [array writeToFile:path atomically:YES];
            break;
        }
    }
    
    return 0;
}

//修改Note方法
-(int) modify:(Note*)model
{
    
    NSString *path = [self applicationDocumentsDirectoryFile];
    NSMutableArray *array = [[NSMutableArray alloc] initWithContentsOfFile:path];
    
    for (NSDictionary* dict in array) {
        
        NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
        [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
        
        NSDate *date = [dateFormatter dateFromString:[dict objectForKey:@"date"]];
        NSString* content = [dict objectForKey:@"content"];
        
        //比较日期主键是否相等
        if ([date isEqualToDate:model.date]){
            [dict setValue:content forKey:@"content"];
            [array writeToFile:path atomically:YES];
            break;
        }
    }
    return 0;
}

//查询所有数据方法
-(NSMutableArray*) findAll
{
    NSString *path = [self applicationDocumentsDirectoryFile];
    
    //[self.listData removeAllObjects];
    NSMutableArray *listData = [[NSMutableArray alloc] init];

    
    NSMutableArray *array = [[NSMutableArray alloc] initWithContentsOfFile:path];
    
    for (NSDictionary* dict in array) {
        
        NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
        [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
        
        Note* note = [[Note alloc] init];
        note.date = [dateFormatter dateFromString:[dict objectForKey:@"date"]];
        note.content = [dict objectForKey:@"content"];
        
        [listData addObject:note];

    }
    return listData;
}

//按照主键查询数据方法
-(Note*) findById:(Note*)model
{
    NSString *path = [self applicationDocumentsDirectoryFile];
    NSMutableArray *array = [[NSMutableArray alloc] initWithContentsOfFile:path];
    
    for (NSDictionary* dict in array) {
        
        NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
        [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
        
        Note* note = [[Note alloc] init];
        note.date = [dateFormatter dateFromString:[dict objectForKey:@"date"]];
        note.content = [dict objectForKey:@"content"];
        
        //比较日期主键是否相等 日期字段是主键
        if ([note.date isEqualToDate:model.date]){
            return note;
        }
    }
    return nil;
}