ios – Swift：CoreData NSManagedObject的自定义设置器

如何在 Swift中为NSManagedobject实现自定义setter.我需要在设置NSMangedobject属性之前完成任务.

解决方法

我的建议是使用KVC.也许不是最优雅的解决方案,但在概念上是KVC的逻辑应用.

观察属性的更改.注册init中的更改(entity：insertIntoManagedobjectContext :)或者在awakeFromFetch和awakeFromInsert中更好,并删除willTurnIntoFault中的观察者.

init(entity: NSEntityDescription!,insertIntoManagedobjectContext context: NSManagedobjectContext!) {
    super.init(entity: entity,insertIntoManagedobjectContext: context)
    addobserver(self,forKeyPath: "attribute",options: NSkeyvalueObservingOptions.New | NSkeyvalueObservingOptions.Old,context: nil)
}


override func observeValueForKeyPath(keyPath: String!,ofObject object: AnyObject!,change: NSDictionary!,context: CMutableVoidPointer) {
    if (keyPath == "attribute") {
           // do what you need to do
    }

}

针对Swift 3进行了更新：

init(entity: NSEntityDescription!,options: [.old,.new],context: nil)
}

override func observeValue(forKeyPath keyPath: String?,of object: Any?,change: [NSkeyvalueChangeKey : Any]?,context: UnsafeMutableRawPointer?) {
    if keyPath == "attribute" {
           // do what you need to do
    }
}