CoreData

// ViewController.m

// UI-NO-42-1 CoreData-1

// Created by 容伟 on 15/10/5.

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CoreData:不需要编写任何SQL语句,直接存取对象;与关系型数据库相比如图：

在CoreData里面存储的都是NSManagerObject具体的对象

CoreData负责管理这些对象之间的关系

只要Xcode里面建立了visual map 就可以新建对象

并把对象添加到数据库里面,同时也可以删除、查询

modle里面包含了实体entity，相当于属性（没写完）

注意：“实体”的名字首字母必须是大写，否则报错！！！！

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操作coreData

1、不管增删改查都需要先初始化上下文[app managedObjectContext]

2、插入具体内容到上下文

+ (id)insertNewObjectForEntityForName:(NSString *)entityName inManagedObjectContext:(NSManagedObjectContext *)context;

3、保存 saveContext

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谓词NSPredicate 条件语句

1、比较运算符>,<,==,>=,<=,!=

可用于数值和字符串等的比较

如：@“age >= 23” 筛选年纪大于23岁的元素

2、范围运算符：IN、BETWEEN

例：@"number BETWEEN {10,50}"

@"address IN {'河南','北京'}"

3、字符串本身:SELF

例：@“SELF == ‘APPLE’"

4、字符串相关：BEGINSWITH、ENDSWITH、CONTAINS

例：@"name CONTAIN[cd] 'ang'" //包含某个字符串

@"name BEGINSWITH[c] 'sh'" //以某个字符串开头

@"name ENDSWITH[d] 'ang'" //以某个字符串结束

注:[c]不区分大小写[d]不区分发音符号即没有重音符号[cd]既不区分大小写，也不区分发音符号。

(5)通配符：

LIKE 模糊查询

例：@"name LIKE[cd] '*b*'" *代表通配符,表示前面后面有一个或多个字符

6、正则表达式

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读取coreData

1、读取managedObjectModel

2、找到里面所有实体的名字[model entitiesByName]

3、找到要读取的实体NSEntityDescription *entry = entryDic[@"UserInfo"];

4、初始化查询对象 NSFetchRequest *request = [[NSFetchRequest alloc]init];

5、通过上下文查找 NSArray *list = [context executeFetchRequest:request error:nil];

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#import "ViewController.h"

#import "AppDelegate.h"

#import "PostView.h"

#import "Message.h"

#import "UserInfo.h"

@interface ViewController ()<UITableViewDataSource, UITableViewDelegate>

{

UITableView *showView;

PostView *postView; // 发布界面

NSArray *dataList;

}

@end

@implementation ViewController

- (void)viewDidLoad {

[super viewDidLoad];

self.edgesForExtendedLayout = UIRectEdgeNone;

self.navigationController.navigationBar.translucent = NO;

self.tabBarController.tabBar.translucent = NO;

[self addRightButtonItem];

[self addShowView];

[self loadData];

}

- (void)addRightButtonItem {

UIBarButtonItem *right = [[UIBarButtonItem alloc] initWithTitle:@"Add" style:UIBarButtonItemStylePlain target:self action:@selector(createPostView)];

self.navigationItem.rightBarButtonItem = right;

}

// 发布界面

- (void)createPostView {

if (postView) {

self.navigationItem.rightBarButtonItem.title = @"Add";

[self done];

[postView removeFromSuperview];

postView = nil;

return;

}

self.navigationItem.rightBarButtonItem.title = @"Done";

postView = [[PostView alloc] initWithFrame:

[UIScreen mainScreen].bounds];

[self.view addSubview:postView];

}

- (void)done {

[postView.titleTextField resignFirstResponder];

[postView.contentTextField resignFirstResponder];

// 如果输入了内容就将之保存到数据库

if (postView.titleTextField.text.length!=0 && postView.contentTextField.text!=0) {

[self addEntity];

}else{

// 没有输入内容

}

// [showView reloadData];

}

- (void)addEntity {

// 操作coreData

// 1、不管增删改查都需要先初始化上下文[app managedObjectContext]

// 2、插入具体内容到上下文

// + (id)insertNewObjectForEntityForName:(NSString *)entityName inManagedObjectContext:(NSManagedObjectContext *)context;

// 3、保存 saveContext

// 1、初始化上下文

NSManagedObjectContext *context = [[AppDelegate appDelegate] managedObjectContext];

// 2、实体描述

Message *message = [NSEntityDescription insertNewObjectForEntityForName:@"Message" inManagedObjectContext:context];

[message setValue:postView.titleTextField.text forKey:@"title"];

[message setValue:postView.contentTextField.text forKey:@"content"];

NSArray *images = @[@"2", @"3", @"4"];

int arc = arc4random()%images.count;

UserInfo *info = [NSEntityDescription insertNewObjectForEntityForName:@"UserInfo" inManagedObjectContext:context];

[info setValue:images[arc] forKey:@"name"];

[info setValue:@(19+arc) forKey:@"age"];

UIImage *image = [UIImage imageNamed:[NSString stringWithFormat:@"%@", images[arc]]]; // 将字符串转换成 data 类型

[info setValue:UIImagePNGRepresentation(image) forKey:@"headerImage"];

[info setValue:message forKey:@"message"];

// 保存数据

[[AppDelegate appDelegate] saveContext];

[self loadData];

}

// 加载数据

- (void)loadData {

// 读取coreData

// 1、读取managedObjectModel

// 2、找到里面所有实体的名字[model entitiesByName]

// 3、找到要读取的实体NSEntityDescription *entry = entryDic[@"UserInfo"];

// 4、初始化查询对象 NSFetchRequest *request = [[NSFetchRequest alloc]init];

// 5、通过上下文查找 NSArray *list = [context executeFetchRequest:request error:nil];

NSManagedObjectContext *context = [[AppDelegate appDelegate] managedObjectContext];

// 1、读取managedObjectModel

NSManagedObjectModel *model = [[AppDelegate appDelegate] managedObjectModel];

// 2、找到里面所有实体的名字[model entitiesByName];

NSDictionary *entitiesDic = [model entitiesByName];

// 3、找到要读取的实体 NSEntityDescription *entry = entryDic[@"UserInfo"];

NSEntityDescription *entity = entitiesDic[@"UserInfo"];

// 4、初始化查询请求对象 NSFetchRequest

NSFetchRequest *request = [[NSFetchRequest alloc] init];

request.entity = entity;

// 5、通过上下文开始查询

dataList = [context executeFetchRequest:request error:nil];

NSLog(@"dataList is %@", dataList);

if (dataList.count != 0) {

[showView reloadData];

}

// 列表内容

- (void)addShowView {

showView = [[UITableView alloc] initWithFrame:CGRectMake(0, 0, CGRectGetWidth(self.view.frame), CGRectGetHeight(self.view.frame)-64) style:UITableViewStylePlain];

showView.delegate = self;

showView.dataSource = self;

[self.view addSubview:showView];

}

#pragma mark - tableView 代理方法

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {

return dataList.count;

}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {

return 100;

}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

NSString *cellId = @"id";

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellId];

if (!cell) {

cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:cellId];

}

UserInfo *info = dataList[indexPath.row];

cell.imageView.image = [UIImage imageWithData:info.headerImage];

cell.textLabel.text = info.name;

Message *message = info.message;

cell.detailTextLabel.text = message.title;

return cell;

}

- (void)didReceiveMemoryWarning {

[super didReceiveMemoryWarning];

// Dispose of any resources that can be recreated.

}

@end

/ PostView.h

// UI-NO-42-1 CoreData-1

// Created by on 15/10/5.

#import <UIKit/UIKit.h>

@interface PostView : UIView

@property (nonatomic, retain)UITextField *titleTextField;

@property (nonatomic, retain)UITextView *contentTextField;

@end

// PostView.m

// UI-NO-42-1 CoreData-1

// Created by 容伟 on 15/10/5.

#import "PostView.h"

@implementation PostView

- (instancetype)initWithFrame:(CGRect)frame {

self = [super initWithFrame:frame];

if (self) {

self.backgroundColor = [UIColor brownColor];

self.titleTextField = [[UITextField alloc] initWithFrame:CGRectMake(10, 100, CGRectGetWidth([UIScreen mainScreen].bounds)-20, 40)];

self.titleTextField.placeholder = @"请输入标题,在下面输入框输入内容";

self.titleTextField.borderStyle = UITextBorderStyleRoundedRect;

[self addSubview:self.titleTextField];

self.contentTextField = [[UITextView alloc] initWithFrame:CGRectMake(10, CGRectGetMaxY(self.titleTextField.frame)+10, CGRectGetWidth([UIScreen mainScreen].bounds)-20, 200)];

self.contentTextField.layer.cornerRadius = 5;

self.contentTextField.layer.borderColor = [UIColor grayColor].CGColor;

self.contentTextField.layer.borderWidth = 1;

[self addSubview:self.contentTextField];

}

return self;

}

@end