1，引入数据库

这里是使用cocoapods导入，手动导入以后有时间会去做

2，查看数据库路径，以及查看数据库的文件

路径一般都是在Documents里面，打印方法：

NSString *path = NSHomeDirectory();//主目录

NSLog(@"NSHomeDirectory:%@",path);

NSString *userName = NSUserName();//与上面相同

NSString *rootPath = NSHomeDirectoryForUser(userName);

NSLog(@"NSHomeDirectoryForUser:%@",rootPath);

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

NSString *documentsDirectory=[paths objectAtIndex:0];//Documents目录

NSLog(@"NSDocumentDirectory:%@",documentsDirectory);

找到数据库的路径，创建成功的话，能看到以.realm 结尾的文件，就是数据库文件，打开该文件的软件我用的是：Realm Browser。   在app store里面可以搜索到的，是免费软件

3，创建数据库

如果是第一次创建数据库，就不用判断版本。但是如果不是第一次建立数据库，比如升级app的时候，在新版本的app数据库中添加了几个属性，这时候就要判断app内数据库的版本，因为如果不判断版本，就会出现崩溃的现象，代码：《一般会在判断版本数据库路径最后，创建数据库这里只是把创建的方法单独提出来了》

//获取数据库路径

NSString * path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)lastObject];

NSString * pathName = [path stringByAppendingString:@"/realmTest.realm"];

RLMRealmConfiguration * config = [RLMRealmConfiguration defaultConfiguration];

//最新版本，每次更新，都要在上次的基础上加一，不能低于之前的版本

config.schemaVersion = 3;

//配置新路径

config.fileURL = [NSURL URLWithString:pathName];

config.migrationBlock = ^(RLMMigration * _Nonnull migration, uint64_t oldSchemaVersion) {

if (oldSchemaVersion < 3) {

NSLog(@"进行数据迁移");

}else{

NSLog(@"不进行数据迁移");

}

};

[RLMRealmConfiguration setDefaultConfiguration:config];

创建数据库：

默认版本创建：

RLMRealm * realm = [RLMRealm defaultRealm];

自定义创建：

NSString * path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)lastObject];

NSString * pathName = [path stringByAppendingString:@"/realmTest.realm"];

RLMRealm * realm = [RLMRealm realmWithURL:[NSURL URLWithString:pathName]];

4，添加数据

首先创建模型

m文件的内容，必不可少

h文件的内容

首先是添加一种数据到数据库，没有包含关系的：

SYDog * dog = [[SYDog alloc]init];

dog.name = [NSString stringWithFormat:@"dog_%u",arc4random()%10];

dog.owner = [NSString stringWithFormat:@"%d",i];

dog.sex = arc4random()%2;

NSInteger cun = self.colorArray.count;

dog.colorStr = self.colorArray[arc4random()%cun];

//默认数据库路径以及名字

/*

RLMRealm *realm = [RLMRealm defaultRealm];

[realm transactionWithBlock:^{

[realm addObject:dog];

}];

*/

//自定义数据库名字和路径

NSString * path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)lastObject];

NSString * pathName = [path stringByAppendingString:@"/realmTest.realm"];

RLMRealm * realm = [RLMRealm realmWithURL:[NSURL URLWithString:pathName]];

[realm transactionWithBlock:^{

[realm addObject:dog];

}];

添加包含数组的数据到数据库《这里的思路跟添加单个差不多，就相当于添加完单个的，再把单个模型作为一个元素添加到数组中》：

SYPreson * presen = [[SYPreson alloc]init];

presen.name = [NSString stringWithFormat:@"地主——%d",i];

presen.age = arc4random()%20;

if (arc4random()%2 == 1) {

presen.isMan = YES;

}else{

presen.isMan = NO;

}

NSInteger a = arc4random()%self.palceArray.count;

presen.adress = [NSString stringWithFormat:@"%@",self.palceArray[a]];

for (int i = 0; i < 10; i++) {

SYDog * dog = [[SYDog alloc]init];

dog.name = [NSString stringWithFormat:@"dog_%u",arc4random()%10];

dog.owner = [NSString stringWithFormat:@"%d",i];

dog.sex = arc4random()%2;

NSInteger cun = self.colorArray.count;

dog.colorStr = self.colorArray[arc4random()%cun];

[presen.dogs addObject:dog];

}

SYClass * clas = [[SYClass alloc]init];

NSInteger year = arc4random()%8;

NSInteger ca = arc4random()%50;

clas.className = [NSString stringWithFormat:@"%ld年级 %ld班",year,ca];

clas.classNumber = [NSString stringWithFormat:@"%u",arc4random()%120];

[presen.classs addObject:clas];

//默认数据库路径

/*

RLMRealm * realm = [RLMRealm defaultRealm];

[realm transactionWithBlock:^{

[realm addObject:presen];

}];

*/

//自定义数据库名字和路径

NSString * path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)lastObject];

NSString * pathName = [path stringByAppendingString:@"/realmTest.realm"];

RLMRealm * realm = [RLMRealm realmWithURL:[NSURL URLWithString:pathName]];

[realm transactionWithBlock:^{

[realm addObject:presen];

}];

查询数据库：

NSString * path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)lastObject];

NSString * pathName = [path stringByAppendingString:@"/realmTest.realm"];

RLMRealm * realm = [RLMRealm realmWithURL:[NSURL URLWithString:pathName]];

//查询所有

RLMResults * presons = [SYPreson allObjectsInRealm:realm];

//    NSLog(@" === %@",presons);

for (SYPreson * pre in presons) {

//        NSLog(@"pwer == %@",pre.name);

}

//按照年龄查询，年龄为int类型

RLMResults * ages = [SYPreson objectsInRealm:realm where:@"age = 12"];

for (SYPreson * age in ages) {

//        NSLog(@"age === %@ %ld",age.name,age.age);

}

//按照名字查询，名字是string类型

RLMResults * dogs = [SYDog objectsInRealm:realm where:@"name = 'dog_2'"];

for (SYDog * dog in dogs) {

//        NSLog(@"dog === %@  %@",dog.name,dog.owner);

}

//多种条件查询

RLMResults * res = [SYPreson objectsInRealm:realm where:@"age < 12 AND adress = '秦朝'"];

for (SYPreson * p in res) {

//        NSLog(@"------ %@ %@ %ld",p.name,p.adress,p.age);

}

//断言查询，查询速度比较快，推荐使用

//断言查询单个数据

NSPredicate * pre = [NSPredicate predicateWithFormat:@"ANY dogs.sex = %ld",1];

RLMResults * resPre = [SYPreson objectsInRealm:realm withPredicate:pre];

for (SYPreson * pres in resPre) {

//        NSLog(@"------ %@ %@ %ld",pres.name,pres.adress,pres.age);

}

//断言查询多个数据条件

NSPredicate * pres = [NSPredicate predicateWithFormat:@"adress = %@",@"秦朝"];

NSPredicate * presN = [NSPredicate predicateWithFormat:@"ANY dogs.name = %@",@"dog_3"];

//链式查询，

RLMResults * resPres = [[SYPreson objectsInRealm:realm withPredicate:pres] objectsWithPredicate:presN];

for (SYPreson * pr in resPres) {

NSLog(@"------ %@ %@ %ld",pr.name,pr.adress,pr.age);

}

修改和删除都是在查询的基础上进行的操作，这里只写出了简单的修改和删除操作

修改数据库

NSString * path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)lastObject];

NSString * pathName = [path stringByAppendingString:@"/realmTest.realm"];

RLMRealm * realm = [RLMRealm realmWithURL:[NSURL URLWithString:pathName]];

//查询出年龄为1的person

RLMResults * per = [SYPreson objectsInRealm:realm where:@"age = 1"];

for (SYPreson * p in per) {

[realm transactionWithBlock:^{

p.name = @"年龄为1，修改名字";

}];

}

删除数据库

NSString * path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)lastObject];

NSString * pathName = [path stringByAppendingString:@"/realmTest.realm"];

RLMRealm * realm = [RLMRealm realmWithURL:[NSURL URLWithString:pathName]];

//删除某一类元素，这里的查询操作跟上面查询操作一样，查询到单个或者多个数据，使用delete方法直接删除

RLMResults * ages = [SYPreson objectsInRealm:realm where:@"age > 14"];

[realm transactionWithBlock:^{

[realm deleteObjects:ages];

}];

//直接删除所有数据

RLMResults * per = [SYPreson allObjectsInRealm:realm];

[realm transactionWithBlock:^{

//单独删除每个数据，如果要删除所有的，要使用循环删除

//        [realm deleteObject:per.lastObject];

//一次性删除一个数组的数据

[realm deleteObjects:per];

}];

RLMResults * dogs = [SYDog allObjectsInRealm:realm];

[realm transactionWithBlock:^{

[realm deleteObjects:dogs];

}];

简单的增删改查，关于realm更深层次的用法会在以后慢慢更新

realm 官网地址：realm