ios 如何在 Swift for Realm 模型中设置主键
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How to set primary key in Swift for Realm model
提问by jeffjv
I'm using Realm in a new iOS Swift project. I'm using Xcode 6.0.1 with iOS SDK 8.0 and Realm 0.85.0
我在一个新的 iOS Swift 项目中使用 Realm。我将 Xcode 6.0.1 与 iOS SDK 8.0 和 Realm 0.85.0 一起使用
I'm trying to use the new Realm primary key feature so I can do an addOrUpdateObject.
我正在尝试使用新的 Realm 主键功能，以便我可以执行addOrUpdateObject.
Here is a sample model:
这是一个示例模型：
import Foundation
import Realm
class Foo: RLMObject {
dynamic var id = 0
dynamic var title = ""
func primaryKey() -> Int {
return id
}
}
And how I'm trying to add/update a new object:
以及我如何尝试添加/更新新对象：
let foo = Foo()
foo.title = titleField.text
foo.id = 1
// Get the default Realm
let realm = RLMRealm.defaultRealm()
// Add to the Realm inside a transaction
realm.beginWriteTransaction()
realm.addOrUpdateObject(foo)
realm.commitWriteTransaction()
I get this error:
我收到此错误：
RLMExecption', reason: ''Foo' does not have a primary key and can not be updated
RLMExecption'，原因：''Foo' 没有主键，无法更新
Here are the docs on the primary key. I'm probably not setting it correctly:
http://realm.io/docs/cocoa/0.85.0/api/Classes/RLMObject.html#//api/name/primaryKey
这是关于主键的文档。我可能没有正确设置它：http:
//realm.io/docs/cocoa/0.85.0/api/Classes/RLMObject.html#//api/name/primaryKey
Latest docs are here now: https://realm.io/docs/objc/latest/api/Classes/RLMObject.html#//api/name/primaryKey
最新文档在这里：https: //realm.io/docs/objc/latest/api/Classes/RLMObject.html#//api/name/primaryKey
回答by Thomas Goyne
primaryKeyneeds to be a class function which returns the name of the property which is the primary key, not an instance method which returns the value of the primary key.
primaryKey需要是一个类函数，它返回作为主键的属性的名称，而不是返回主键值的实例方法。
class Foo: RLMObject {
dynamic var id = 0
dynamic var title = ""
override class func primaryKey() -> String? {
return "id"
}
}
回答by CherryKuczery
The return type of primaryKey()is optional:
的返回类型primaryKey()是可选的：
class Foo: RLMObject {
dynamic var id = 0
dynamic var title = ""
override class func primaryKey() -> String? {
return "id"
}
}
回答by Maria Ortega
For Swift 5:
对于 Swift 5：
import RealmSwift
class Signature: Object {
@objc dynamic var id = ""
override static func primaryKey() -> String? {
return "id"
}
}
To avoid: Terminating app due to uncaught exception 'RLMException', reason: 'Primary key property 'id' does not exist on object.
避免：由于未捕获的异常“RLMException”而终止应用程序，原因：对象上不存在“主键属性”“id”。
