1.安装
如果使用
cocoapods,示例语句如下
platform :ios, '8.0'
target 'Simona_Realm' do
pod 'Realm', '~> 3.0.0-beta.3'
end
2.创建简易模型,继承于RLMObject,存储在数据库的模型都需要继承于RLMObject
Person.h
#import <Realm/Realm.h>
RLM_ARRAY_TYPE(Person);
@interface Person : RLMObject
@property NSString *personId;
@property BOOL status;
@property NSString *sex;
@end
Person.m
#import "Person.h"
@implementation Person
// 设置主键,确保数据唯一性
+ (NSString *)primaryKey {
return @"personId";
}
// 设置属性不为nil
+ (NSArray<NSString *> *)requiredProperties {
return @[@"sex"];
}
// 设置忽略属性
+ (NSArray<NSString *> *)ignoredProperties {
return @[];
}
// 设置默认值,对于不为null的属性,默认给空
+ (NSDictionary *)defaultPropertyValues {
return @{@"sex":@""};
}
//索引属性,主要用于搜索,根据性别进行搜索
+ (NSArray<NSString *> *)indexedProperties {
return @[@"sex",@"woman"];
}
@end
关于RLMObject
1.Realm忽略了OC的属性特性(如nonatomic, atomic, strong,retain, weak,copy等),所以在声明属性时可不写,，这些特性会一直生效直到被写入数据库。
2.Realm支持以下的类型BOOL, NSInteger, long, double, CGFloat, NSString, NSDate, NSData等
3.定义了RLM_ARRAY_TYPE(Person)表示支持RLMArray属性,相当于允许RLMArray<Person>属性的使用,例如:在其他属性里可@property RLMArray<Person *><Person> *personal如此使用,相当于继承关系(本文暂不做赘述)
3.使用
<1.>存储
模拟存储一万条假数据
RLMRealm *realm = [RLMRealm defaultRealm];
[realm transactionWithBlock:^{
for (int i = 0; i < 10000; i++) {
Person *person = [[Person alloc]init];
person.personId = [NSString stringWithFormat:@"张%d",i];
person.sex = @"Not scanned";
person.status = YES;
[realm addObject:person];
}
}];
这里的
[realm transactionWithBlock:^{ }];
等同于
[realm beginWriteTransaction];
[realm commitWriteTransaction];
每次打开关闭数据库时都应执行此操作
<2.>删除
RLMRealm *realm = [RLMRealm defaultRealm];
[realm beginWriteTransaction];
[realm deleteAllObjects];
[realm commitWriteTransaction];
<3.>查询
1.根据谓词查询
// RLMResults相当于查询到的数组
NSPredicate *pred = [NSPredicate predicateWithFormat:@"status = %ld", NO];
RLMResults *result = [Person objectsWithPredicate:pred];
Person *per = result[indexPath.row];
2.根据条件查询
RLMResults *result = [Person objectsWhere:@"status = 'NO' AND personId BEGINSWITH '张1'"];
Person *per = result[indexPath.row];
3.查询所有
RLMResults *persons = [Person allObjects];
Person *per = persons[indexPath.row];
<4.>更新
1.更新数据里某一属性值
NSPredicate *pred = [NSPredicate predicateWithFormat:@"personId = %@", strScan];
RLMResults *result = [Person objectsWithPredicate:pred];
if (result.count != 0) {
RLMRealm *r = [RLMRealm defaultRealm];
[r beginWriteTransaction];
//直接修改
Person *person = result[0];
person.sex = @"Has been scanned";
person.status = NO;
[r commitWriteTransaction];
}
2.创建一个新值并更新数据库,createOrUpdateInRealm:通过主键来更新插入
NSPredicate *pred = [NSPredicate predicateWithFormat:@"personId = %@", strScan];
RLMResults *result = [Person objectsWithPredicate:pred];
if (result.count != 0) {
Person *person = [[Person alloc]init];
person.personId = @"Simona1";
person.sex = @"woman";
person.status = NO;
RLMRealm *r = [RLMRealm defaultRealm];
[r beginWriteTransaction];
[Person createOrUpdateInRealm:r withValue:person];
[r commitWriteTransaction];
