core data CRUD简单操作

朱雀 2022-08-01 13:50 218阅读 0赞

//
    //  ViewController.m
    //  MyCoreData
    //
    //  Created by 麦子 on 15/7/11.
    //  Copyright (c) 2015年 麦子. All rights reserved.
    //
    
    #import "ViewController.h"
    #import "AppDelegate.h"
    #import "Person.h"
    #import "Card.h"
    
    @interface ViewController (){
       
        AppDelegate *app;
        NSManagedObjectContext *context; // 数据库API操作类
        Person *person;
        Card *card;
    
    }
    
    @end
    
    /**
     打开CoreData的SQL语句输出开关
     1.打开Product，点击EditScheme...
     2.点击Arguments，在ArgumentsPassed On Launch中添加2项
     1> -com.apple.CoreData.SQLDebug
     2> 1
     
     */
    
    @implementation ViewController
    
    - (void)viewDidLoad {
        [super viewDidLoad];
        
        // 创建数据库
        app = [UIApplication sharedApplication].delegate;
        context = app.managedObjectContext;
        
        NSLog(@"%@--",[app applicationDocumentsDirectory]);
        
    //    [self addData];
         [self queryData];
    //    [self updateData];
        [self delData];
    }
    
    #pragma mark --- 添加数据
    - (void)addData{
        // 人群表
        person = [NSEntityDescription insertNewObjectForEntityForName:@"Person" inManagedObjectContext:context];
        // 组装数据
        person.name = @"小红";
        person.age = [NSNumber numberWithInt:25];
        
        // 身份证表
        card = [NSEntityDescription insertNewObjectForEntityForName:@"Card" inManagedObjectContext:context];
        card.no = @"123456789";
        
        person.card = card;
        
        // 同步到数据库
        NSError *error = nil;
        BOOL flag = [context save:&error]; // 这一步才是同步，也就是commit操作
        if (flag) {
            NSLog(@"数据保存成功。。。。");
        }else{
            NSLog(@"%@",error.description);
        }
    }
    
    
    #pragma mark ----- 查询
    - (void)queryData{
        // 找到需要的表
        NSEntityDescription *personDes = [NSEntityDescription entityForName:@"Person" inManagedObjectContext:context];
        // 初始化一个查询请求
        NSFetchRequest *request = [[NSFetchRequest alloc] init];
        // 设置要查询的实体
        [request setEntity:personDes];
        // 条件设置
        NSPredicate *pred = [NSPredicate predicateWithFormat:@" name like %@",@"小*"];
    //    [request setPredicate:pred];
        
        
        // 运行SQL
        NSError *err;
        NSArray *dataArray = [context executeFetchRequest:request error:&err];
        if (dataArray) {
            for (Person *personEntity in dataArray) {
                
                NSLog(@"person 数据－－%@--%d-%@",personEntity.name,[personEntity.age intValue],personEntity.card.no);
            }
        }
        
        if (err) {
            NSLog(@"%@--",err.description);
        }
    }
    
    
    #pragma mark  修改
    - (void)updateData{
        NSEntityDescription *pEntity = [NSEntityDescription entityForName:@"Person" inManagedObjectContext:context];
        
        NSFetchRequest *request = [[NSFetchRequest alloc] init];
        request.entity = pEntity;
        
    //    NSPredicate *pred = [NSPredicate predicateWithFormat:@"name like %@",@"麦子*"];
    //    [request setPredicate:pred];
        
        NSError *err = nil;
        NSArray *arryData = [context executeFetchRequest:request error:&err];
        int count = 0;
        for (Person *personEntity in arryData) {
            
            NSLog(@"person 修改－－名字：%@--年龄：%d-－身份证：%@",personEntity.name,[personEntity.age intValue],personEntity.card.no);
            
             ++count;
            personEntity.name = [NSString stringWithFormat:@"哈哈%d",count];
            personEntity.card.no = @"110";
        }
        if (err) {
            NSLog(@"%@",err.description);
        }
    
        // 修改后提交，就可以改变数据
        bool flag = [context save:&err];
        if (flag) {
            NSLog(@"修改成功");
        }else{
            NSLog(@"%@",err.description);
        }
        
    }
    
    
    #pragma mark -- 删除
    - (void)delData{
       
        NSEntityDescription *perDes = [NSEntityDescription entityForName:@"Person" inManagedObjectContext:context];
        NSFetchRequest *request = [[NSFetchRequest alloc] init];
        request.entity = perDes;
        
        NSPredicate *pre = [NSPredicate predicateWithFormat:@" name = %@",@"哈哈3"];
        [request setPredicate:pre];
        
        NSError *error = nil;
        NSArray *array = [context executeFetchRequest:request error:&error];
        for (Person *personEntity in array) {
            NSLog(@"person 修改－－名字：%@--年龄：%d-－身份证：%@",personEntity.name,[personEntity.age intValue],personEntity.card.no);
            
            [context deleteObject:personEntity];
        }
    
        //  删除，修改，添加， 都需要最后的这个方法，进行commit
        bool flag = [context save:&error];
        if ([array count] > 0) {
            if (flag ) {
                NSLog(@"删除成功");
            }else{
                NSLog(@"%@",error.description);
            }
        }
        
    
    
    }
    
    
    
    
    
    
    
    - (void)didReceiveMemoryWarning {
        [super didReceiveMemoryWarning];
         
    }
    
    @end

Person 和 Card 关联。