コアデータ内のユニークな属性/列値を取得する

Question

属性値が 'id'、 'brand'、 'category'、 'mrp'のエンティティCalculatorProduct を持っています 「カテゴリ」列/属性

let context = DataBaseController.getContext() 
    let fetchRequest:NSFetchRequest<CalculatorProduct> = CalculatorProduct.fetchRequest() 

    fetchRequest.propertiesToFetch = ["category"] 

    fetchRequest.returnsDistinctResults = true 
    do{ 

     let result = try context.fetch(fetchRequest) 


     print("array from db \(String(describing: result.count))") 
     print("array from db \(String(describing: result))") 

     for val in result{ 

      print("\(String(describing: val.category))") 
     } 

    } 
    catch{ 

     print("error in fetching is\(error)") 
    } 

Answer 1

は、以下のことを試してみてください。

let context = DataBaseController.getContext() 
let fetchRequest:NSFetchRequest<CalculatorProduct> = CalculatorProduct.fetchRequest() 
fetchRequest.propertiesToFetch = ["category"] 
fetchRequest.returnsDistinctResults = true 
fetchRequest.resultType = .dictionaryResultType 
do { 
    let result = try context.fetch(fetchRequest) as! [[String:Any]] 

    print("array from db \(String(describing: result.count))") 
    print("array from db \(String(describing: result))") 

    for val in result{ 
     print("\(String(describing: val["category"]))") 
    } 
} 
catch{ 
    print("error in fetching is\(error)") 
}