Realm简单使用

1. Realm是用来代替CoreData和SQLite的数据存储方式，支持的类型有Bool,Int16,Int32,Int64,Double,Float,String,Date,Data

2. 在swift中，创建一个Dog类，继承自Object，如下所示：

    class Dog: Object {
    @objc dynamic var name = ""
    @objc dynamic var age = 0
    @objc dynamic var key = 0
    //主键
    override static func primaryKey() -> String? {
    return "key"
    }
    }
   

   然后在创建一个Person类，同样继承自Object类，在Person类中可能拥有多个dog属性，如下：

    class Person: Object {
    @objc dynamic var name = ""
    @objc dynamic var age = 0
    @objc dynamic var isEat = false
    var dogs = List()
    }
   

   在Realm中List相当于swift中的数组，要声明List中的数据类型。

3. 增，删，改，查

   • 添加一个dog对象

       let realm = try! Realm()
       let myDog = Dog()
       
       myDog.name = "canader"
       myDog.key = 1
       myDog.age = 20
       
       //增
       try! realm.write {
       realm.add(myDog)
       }
       
       //删
       try! realm.write {
       
           //删除myDog
       realm.delete(myDog)
       //删除所有
       realm.deleteAll()
       }
     
       //改
       try! realm.write {
       myDog.name = "JACK"
       }
       
       //通过主键更新
        try! realm.write {
           //如果有主键为默认值的对象，那么久更新
       realm.add(myDog, update: true)
       }
       
       //通过键值编码更新属性
       try! realm.write {
       myDog.setValue("Rose", forKeyPath: "name")
       }
       
       //查
       //获取所有的dog属性
       let result = realm.objects(Dog.self)
       
       //过滤获取到的Dog属性
       let result = realm.objects(Dog.self).filter("age > 0")
     

   • 添加一个person对象

       //增
       let dog2 = Dog()
       dog2.name = "dog2"
       dog2.age = 10
       dog2.key = 2
     
       let person1 = Person()
       person1.name = "wangwu"
       person1.age = 20
       person1.isEat = true
       //给Person的dogs属性添加对象
       person1.dogs.append(myDog)
       person1.dogs.append(dog2)
       try! realm.write {
       realm.add(person1)
       }
       
       
       //删
       try! realm.write {
       realm.delete(persons)
       }
       
       
       //改
       let result = realm.objects(Person.self)
       print(result.count)
       for i in 0..