基于iOS Realm数据库的使用实例详解
时间：2020-10-04 14:43:50|栏目：iOS代码|点击： 次
首先下载Realm源代码，https://realm.io/cn/docs/objc/latest
将下载的文件解压，从 ios/static/ 目录中将 Realm.framework 拖曳到 Xcode 工程的文件导航器内，然后在 Xcode 文件导航器中选中工程。然后选择应用目标，前往 Build Phases 选项卡。在 Link Binary with Libraries 部分中单击 + 按钮，然后添加 libc++.tbd 和 libz.tbd。这样还没有完，我们还需要安装插件，打开解压文件夹下的plugin，运行RealmPlugin.xcodeproj，然后重启XCode。
这样环境配置就完了，现在说重点如何去使用。
1.创建实体类
new File翻到最下面点击创建Realm实体类
#import <Realm/Realm.h> @interface TestBean : RLMObject @property NSString* name; @property NSInteger age; @end // This protocol enables typed collections. i.e.: // RLMArray<TestBean *><TestBean> RLM_ARRAY_TYPE(TestBean) #import "TestBean.h" @implementation TestBean @end
2.增删改查
这个增加，可以看到直接添加实体类就行了，这个RLMRealm就是数据库的操作类，以后所有操作都靠他。
-(void)addAction{
NSLog(@"add");
self.name = _tf_name.text;
self.age = [_tf_age.text integerValue];
TestBean* bean = [[TestBean alloc]init];
bean.name = self.name;
bean.age = self.age;
RLMRealm *realm = [RLMRealm defaultRealm];
[realm transactionWithBlock:^{
[realm addObject:bean];
}];
}
删除也是通过删除实体类来实现，但是我们需要首先通过查询出实体类才行。这个查询我们可以看到通过我们创建的实体类就能实现
-(void)deleteAction{
NSLog(@"delete");
RLMResults *dogs = [TestBean allObjects];
RLMRealm *realm = [RLMRealm defaultRealm];
[realm transactionWithBlock:^{
for (TestBean *bean in dogs) {
[realm deleteObject:bean];
}
}];
}
更新也是通过改变实体类的数据来实现
-(void)updateAction{
NSLog(@"update");
RLMResults *dogs = [TestBean allObjects];
[[RLMRealm defaultRealm] transactionWithBlock:^{
for (TestBean *bean in dogs) {
bean.name = @"李四";
}
}];
}
查询我们还可以添加条件
// 使用断言字符串来查询
RLMResults<Dog *> *tanDogs = [Dog objectsWhere:@"color = 'tan' AND name BEGINSWITH 'B'"];
// 使用 NSPredicate 来查询
NSPredicate *pred = [NSPredicate predicateWithFormat:@"color = %@ AND name BEGINSWITH %@",
@"tan", @"B"];
tanDogs = [Dog objectsWithPredicate:pred];
3.排序
这个是在查询完后去实现，通过实体类的key来排序。
-(void)sortAction{
NSLog(@"query");
RLMResults *dogs = [[TestBean allObjects] sortedResultsUsingKeyPath:@"name" ascending:YES];
[[RLMRealm defaultRealm] transactionWithBlock:^{
for (TestBean *bean in dogs) {
NSLog(@"%@",bean.name);
}
}];
}
4.小结
只说了常用的功能，贴上官方中文文档供大家参考
https://realm.io/cn/docs/objc/latest
5.例子代码
//
// ViewController.m
// BmobTest
//
// Created by shanreal-iOS on 2017/12/9.
// Copyright © 2017年 shanreal.LongZhenHao. All rights reserved.
//
#import "ViewController.h"
#import "TestBean.h"
@interface ViewController ()
@property(nonatomic,strong)UIButton* add;
@property(nonatomic,strong)UIButton* delete;
@property(nonatomic,strong)UIButton* update;
@property(nonatomic,strong)UIButton* query;
@property(nonatomic,strong)UIButton* sort;
@property(nonatomic,strong)NSString* name;
@property(nonatomic,assign)NSInteger* age;
@property(nonatomic,strong)UITextField* tf_name;
@property(nonatomic,strong)UITextField* tf_age;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
_add = [[UIButton alloc]initWithFrame:CGRectMake(10, 30, 100, 20)];
[_add setTitle:@"add" forState:UIControlStateNormal];
[_add setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
[_add addTarget:self action:@selector(addAction) forControlEvents:UIControlEventTouchUpInside];
_delete = [[UIButton alloc]initWithFrame:CGRectMake(10, 60, 100, 20)];
[_delete setTitle:@"delete" forState:UIControlStateNormal];
[_delete setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
[_delete addTarget:self action:@selector(deleteAction) forControlEvents:UIControlEventTouchUpInside];
_update = [[UIButton alloc]initWithFrame:CGRectMake(10, 90, 100, 20)];
[_update setTitle:@"update" forState:UIControlStateNormal];
[_update setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
[_update addTarget:self action:@selector(updateAction) forControlEvents:UIControlEventTouchUpInside];
_query = [[UIButton alloc]initWithFrame:CGRectMake(10, 120, 100, 20)];
[_query setTitle:@"query" forState:UIControlStateNormal];
[_query setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
[_query addTarget:self action:@selector(queryAction) forControlEvents:UIControlEventTouchUpInside];
_sort = [[UIButton alloc]initWithFrame:CGRectMake(10, 150, 100, 20)];
[_sort setTitle:@"sort" forState:UIControlStateNormal];
[_sort setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
[_sort addTarget:self action:@selector(sortAction) forControlEvents:UIControlEventTouchUpInside];
_tf_name = [[UITextField alloc]initWithFrame:CGRectMake(50, 300, 200, 20)];
_tf_name.placeholder=@"name";
_tf_age = [[UITextField alloc]initWithFrame:CGRectMake(50, 350, 200, 20)];
_tf_age.placeholder=@"age";
[self.view addSubview:_add];
[self.view addSubview:_delete];
[self.view addSubview:_update];
[self.view addSubview:_query];
[self.view addSubview:_sort];
[self.view addSubview:_tf_name];
[self.view addSubview:_tf_age];
}
-(void)addAction{
NSLog(@"add");
self.name = _tf_name.text;
self.age = [_tf_age.text integerValue];
TestBean* bean = [[TestBean alloc]init];
bean.name = self.name;
bean.age = self.age;
RLMRealm *realm = [RLMRealm defaultRealm];
[realm transactionWithBlock:^{
[realm addObject:bean];
}];
}
-(void)deleteAction{
NSLog(@"delete");
RLMResults *dogs = [TestBean allObjects];
RLMRealm *realm = [RLMRealm defaultRealm];
[realm transactionWithBlock:^{
for (TestBean *bean in dogs) {
[realm deleteObject:bean];
}
}];
}
-(void)updateAction{
NSLog(@"update");
RLMResults *dogs = [TestBean allObjects];
[[RLMRealm defaultRealm] transactionWithBlock:^{
for (TestBean *bean in dogs) {
bean.name = @"李四";
}
}];
}
-(void)queryAction{
NSLog(@"query");
RLMResults *dogs = [TestBean allObjects];
[[RLMRealm defaultRealm] transactionWithBlock:^{
for (TestBean *bean in dogs) {
NSLog(@"%@",bean.name);
}
}];
}
-(void)sortAction{
NSLog(@"query");
RLMResults *dogs = [[TestBean allObjects] sortedResultsUsingKeyPath:@"name" ascending:YES];
[[RLMRealm defaultRealm] transactionWithBlock:^{
for (TestBean *bean in dogs) {
NSLog(@"%@",bean.name);
}
}];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
@end
