识别coreData属性的类型 [英] identify coreData Attribute's type

问题描述

我正在编写一个库，该库允许开发人员将SQL代码应用于coreData，如下所示:

Im writing a library that allows developers to apply SQL code on coreData like so:

let manager = coreSQL()
manager.prepare("INSERT INTO Entity (name, age) VALUES (?,?)")
manager.execute(["Chuck Norris" , "76"])

要插入coreData中，我要使用此

to insert in coreData i use this

let context:NSManagedObjectContext = appDel.managedObjectContext
let newRow = NSEntityDescription.insertNewObjectForEntityForName(tableName, inManagedObjectContext: context)
if (columnsArray.count == values.count){
    for i in 0 ..< columnsArray.count{
        newRow.setValue(values[i], forKey: columnsArray[i])
    }
    do {try context.save()} catch _ {}
}

• columnsArray = [名称"，年龄"]

  值= [查克·诺里斯"(Chuck Norris)，"76"]

  问题在于，在我的coreData对象中，age Attribute的类型为Integer，并且您可能会注意到Chuck Norris的age为String，因此当我尝试执行我的应用程序时会收到错误消息:

  the problem is that in my coreData object the age Attribute is of type Integer and as you may noticed Chuck Norris's age is String so when i try to execute my application i get an error :

  由于未捕获的异常"NSInvalidArgumentException"而终止应用程序，原因:属性的值的类型不可接受:property ="age"；所需的类型= NSNumber；给定类型= _TtCs19_NSContiguousString;值= 76.'

  问题是:如何识别属性类型以将值转换为相同类型

  The question is: how can i identify the attribute type in order to cast the value to the same type

  推荐答案

  您可以通过询问实体来标识属性类型:

  You can identify the attribute type by asking the entity:

  let context:NSManagedObjectContext = appDel.managedObjectContext
  let newRow = NSEntityDescription.insertNewObjectForEntityForName(tableName, inManagedObjectContext: context)
  let attributes = newRow.entity().attributesByName()
  if (columnsArray.count == values.count){
      for i in 0 ..< columnsArray.count{
          let attributeDescription = newRow.entity.attributesByName[columnsArray[1]]
          switch attributeDescription.attributeType {
          case StringAttributeType:
          }
          newRow.setValue(values[i], forKey: columnsArray[i])
      }
      try! context.save()
  }    
  

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