Core Data 自动生成及基本数据操作（3）

在前面两小节中已介结了ＣＯＲＥＤＡＴＡ自动生成ＭＯＤＥＬ框架。

本节主要对ＣＯＲＥＤＡＴＡ进行基本的数据操作。

首先为了能进行演示，动态创建了几个按钮；

代码如下：

- (void)CreateButton
{

    UIButton *newbtn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [newbtn setTitle:@"insert" forState:UIControlStateNormal];
    CGRect rect = CGRectMake(40, 40, 80, 20);
    newbtn.tag = 1;
    newbtn.frame = rect;
    [newbtn addTarget:self action:@selector(btnClick:) forControlEvents:UIControlEventTouchUpInside];
    
    UIButton *modifybtn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [modifybtn setTitle:@"edit" forState:UIControlStateNormal];
    CGRect rect1 = CGRectMake(180, 40, 80, 20);
    modifybtn.tag = 2;
    modifybtn.frame = rect1;
    [modifybtn addTarget:self action:@selector(btnClick:) forControlEvents:UIControlEventTouchUpInside];
    
    UIButton *delbtn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [delbtn setTitle:@"delete" forState:UIControlStateNormal];
    CGRect rect2 = CGRectMake(40, 80, 80, 20);
    delbtn.tag = 3;
    delbtn.frame = rect2;
    [delbtn addTarget:self action:@selector(btnClick:) forControlEvents:UIControlEventTouchUpInside];
    
    UIButton *selectbtn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [selectbtn setTitle:@"query" forState:UIControlStateNormal];
    CGRect rect3 = CGRectMake(180, 80, 80, 20);
    selectbtn.tag = 4;
    selectbtn.frame = rect3;
    [selectbtn addTarget:self action:@selector(btnClick:) forControlEvents:UIControlEventTouchUpInside];
    
    UIButton *insert1v1btn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [insert1v1btn setTitle:@"insert 1V1" forState:UIControlStateNormal];
    CGRect rect4 = CGRectMake(40, 120, 80, 20);
    insert1v1btn.tag = 5;
    insert1v1btn.frame = rect4;
    [insert1v1btn addTarget:self action:@selector(btnClick:) forControlEvents:UIControlEventTouchUpInside];
    
    UIButton *del1v1btn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [del1v1btn setTitle:@"del 1V1" forState:UIControlStateNormal];
    CGRect rect5 = CGRectMake(180, 120, 80, 20);
    del1v1btn.tag = 6;
    del1v1btn.frame = rect5;
    [del1v1btn addTarget:self action:@selector(btnClick:) forControlEvents:UIControlEventTouchUpInside];
    
    UIButton *insert1vNbtn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [insert1vNbtn setTitle:@"insert 1VN" forState:UIControlStateNormal];
    CGRect rect6 = CGRectMake(40, 160, 80, 20);
    insert1vNbtn.tag = 7;
    insert1vNbtn.frame = rect6;
    [insert1vNbtn addTarget:self action:@selector(btnClick:) forControlEvents:UIControlEventTouchUpInside];
    
    UIButton *del1vNbtn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [del1vNbtn setTitle:@"del 1VN for 1" forState:UIControlStateNormal];
    CGRect rect7 = CGRectMake(180, 160, 80, 20);
    del1vNbtn.tag = 8;
    del1vNbtn.frame = rect7;
    [del1vNbtn addTarget:self action:@selector(btnClick:) forControlEvents:UIControlEventTouchUpInside];
    
    UIButton *del1vNforNbtn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [del1vNforNbtn setTitle:@"del 1VN for N" forState:UIControlStateNormal];
    CGRect rect8 = CGRectMake(40, 200, 80, 20);
    del1vNforNbtn.tag = 9;
    del1vNforNbtn.frame = rect8;
    [del1vNforNbtn addTarget:self action:@selector(btnClick:) forControlEvents:UIControlEventTouchUpInside];
    
    
    [self.window addSubview:newbtn];
    [self.window addSubview:modifybtn];
    [self.window addSubview:delbtn];
    [self.window addSubview:selectbtn];
    [self.window addSubview:insert1v1btn];
    [self.window addSubview:del1v1btn];
    [self.window addSubview:insert1vNbtn];
    [self.window addSubview:del1vNbtn];
    [self.window addSubview:del1vNforNbtn];
}

添加点击事件处理方法：其中的调用方法后面将一一列出。

- (IBAction)btnClick:(id)sender
{
    switch (((UIButton*)sender).tag) {
        case 1:
            [self insertData];
            break;
        case 2:
            [self modifyData];
            break;
        case 3:
            [self deleteData];
            break;
        case 4:
            [self queryData];
            break;
        case 5:    
            [self insert1V1Data];
            break;
        case 6:
            [self delete1V1Data:2];
            break;
        case 7:
            [self insert1VNData];
            break;
        case 8:
            [self delete1VNof1Data];
            break;
        case 9:
            [self delete1VNofNData];
            break;
        default:
            break;
    }
}

修改下面方法添加

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
    // Override point for customization after application launch.
    self.window.backgroundColor = [UIColor whiteColor];

   //在这里进行动态创建按钮
    [self CreateButton];
    
    [self.window makeKeyAndVisible];

    
    return YES;
}

运行界面如下：

下面执行基本的数据增删改，操作。

新增：

//插入表数据
- (void)insertData
{
    NSManagedObjectContext *context = [self managedObjectContext];
    NSManagedObject *carItem = [NSEntityDescription insertNewObjectForEntityForName:@"Car" inManagedObjectContext:context];
    [carItem setValue:@"engin for b" forKey:@"engine"];
    [carItem setValue:@"name for bmw" forKey:@"name"];
    [carItem setValue:@"wheel for mq" forKey:@"wheel"];
    
    NSManagedObject *carStyleItem = [NSEntityDescription insertNewObjectForEntityForName:@"CarStyle" inManagedObjectContext:context];
    [carStyleItem setValue:@"cl" forKey:@"color"];

    //要注意数据类型，这里值和类型不一至时异常错误时提示不友好，不好排查
    [carStyleItem setValue:[NSNumber numberWithInt:12] forKey:@"width"];
    [carStyleItem setValue:[NSNumber numberWithInt:200] forKey:@"height"];
    
    //设置关系
    [carStyleItem setValue:carItem forKey:@"main"];
    [carItem setValue:carStyleItem forKey:@"details"];
    
    NSError *saveerror;
    if (![context save:&saveerror])
    {
        NSLog(@"don't save %@",[saveerror localizedDescription]);
    }
}

修改数据：

//修改数据 这里只是对上面插入数据的某个记录进行查找出来后进行修改。
- (void)modifyData
{
    NSManagedObjectContext *context = [self managedObjectContext];
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Car" inManagedObjectContext:context];
    NSFetchRequest *cmd = [[[NSFetchRequest alloc]init]autorelease];
    [cmd setEntity:entity];
    //设置查询条件
    NSPredicate *condition = [NSPredicate predicateWithFormat:@"name = %@",@"name for bmw"];
    [cmd setPredicate:condition];
    
    NSArray *records = [context executeFetchRequest:cmd error:nil];
    
    if ([records count]>0) {
        NSManagedObject *rec = [records objectAtIndex:0];
        //修改数据
        [rec setValue:@"modify engine" forKey:@"engine"];
        //进行保存
        [context save:nil];
    }
}

删除数据

//删除数据
- (void)deleteData
{
    NSManagedObjectContext *context = [self managedObjectContext];
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"CarStyle" inManagedObjectContext:context];
    NSFetchRequest *cmd = [[[NSFetchRequest alloc]init]autorelease];
    [cmd setEntity:entity];
    //设置查询条件
    NSPredicate *condition = [NSPredicate predicateWithFormat:@"color = %@",@"cl"];
    [cmd setPredicate:condition];
    
    NSArray *records = [context executeFetchRequest:cmd error:nil];
    
    if ([records count]>0) {
        NSManagedObject *rec = [records objectAtIndex:0];
        
        [context deleteObject:rec];
        
        [context save:nil];
    }
}

查找数据

- (void)queryData
{
    NSManagedObjectContext *context = [self managedObjectContext];
    NSFetchRequest *fetchreq = [[[NSFetchRequest alloc]init] autorelease];
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Car" inManagedObjectContext:context];
    
    [fetchreq setEntity:entity];
    NSError *err;
    NSArray *fetchedObjects = [context executeFetchRequest:fetchreq error:&err];
    NSInteger count = [fetchedObjects count];
    NSLog(@"record count = %i",count);
    for (NSManagedObject *car in fetchedObjects)
    {
        NSLog(@"name = %@",[car valueForKey:@"name"]);
        NSLog(@"engine = %@",[car valueForKey:@"engine"]);
        NSLog(@"wheel = %@",[car valueForKey:@"wheel"]);
        
        NSManagedObject *carstyle = [car valueForKey:@"details"];
        NSLog(@"color = %@",[carstyle valueForKey:@"color"]);
        NSLog(@"width = %@",[carstyle valueForKey:@"width"]);
        NSLog(@"height = %@",[carstyle valueForKey:@"height"]);
        
    }
}

本节主要介绍增删改查操作。下节将讲解实体与实体之间的关系删除操作。