NSFetchrRequst.propertiesToFetch中的NSRelationshipDescription的cooresponding返回值類型是什麼？

我用一個NSFetchRequest獲取分組數據，要分組的屬性是一個關係屬性，我也希望獲得返回結果。所以我設置NSFetchRequest的propertiesToFetch和propertiesToGroupBy。執行結果是一個字典數組。但我無法獲得關係的目標對象。或者我應該如何獲得關係的目標對象？代碼如下NSFetchrRequst.propertiesToFetch中的NSRelationshipDescription的cooresponding返回值類型是什麼？

let entityDesc = NSEntityDescription.entityForName("Record" as NSString, inManagedObjectContext: moc) 

    let relationDesc:NSRelationshipDescription = entityDesc?.relationshipsByName["relationName" as NSString] as NSRelationshipDescription; 

    let keyPathExpression = NSExpression(forKeyPath: "time" as NSString) 
    let countExpression = NSExpression(forFunction: "count:", arguments: [keyPathExpression]) 
    var countExpDescription = NSExpressionDescription() 
    countExpDescription.name = "count"; 
    countExpDescription.expression = countExpression; 
    countExpDescription.expressionResultType = NSAttributeType.Integer32AttributeType; 


    let fetchRequest = NSFetchRequest(entityName: "Record" as NSString) 
    fetchRequest.propertiesToFetch = [relationDesc, countExpDescription]; 
    fetchRequest.resultType = NSFetchRequestResultType.DictionaryResultType; 
    fetchRequest.propertiesToGroupBy = [relationDesc]; 


    let results = moc.executeFetchRequest(fetchRequest, error: nil)

我設置在fetchRequest的proertiesToFetch的NSRelationshipDescription，上面的代碼可以編譯和運行，但是當我嘗試獲取結果

for eachResult in results! 
    { 
    let eachResultDict = eachResult as [String:AnyObject]; 

    let relatedObject = eachResultDict["relationName"] ; 
    let count = eachResultDict["count"] ; 
    }

我不能確定如何處理則relatedObject做，它不是目標數據模型的類型......當我嘗試打印它時，它只是返回一個十六進制數字....如何獲取相關對象？的代碼是有點長，我希望我的標題有助於使主題明確〜，謝謝〜

來源

2014-10-22 jx ch

relationDesc:NSRelationshipDescription不是NSExpressionDescription

嘗試編碼類似於你如何編碼的countExpDescription一個relationName:NSExpressionDescription。

來源

2015-01-25 12:09:12 adamek

NSFetchrRequst.propertiesToFetch中的NSRelationshipDescription的cooresponding返回值類型是什麼？

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