如何使用coredata iOS Swift从实体中提取ID为的重复记录。我使用了以下内容，但没有得到正确的结果。任何建议都将不胜感激。提前谢谢。
func fetchDuplicateRecords() {
let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "EmployeeData")
let nameExpr = NSExpression(forKeyPath: "name")
let countExpr = NSExpressionDescription()
let countVariableExpr = NSExpression(forVariable: "Id")
countExpr.name = "count"
countExpr.expression = NSExpression(forFunction: "count:", arguments: [ nameExpr, nameExpr1, nameExpr2 ])
countExpr.expressionResultType = .integer64AttributeType
do {
fetchRequest.resultType = .dictionaryResultType
let idDescriptor: NSSortDescriptor = NSSortDescriptor(key: "Id", ascending: true)
fetchRequest.sortDescriptors = [idDescriptor]
fetchRequest.propertiesToGroupBy = ["name"]
fetchRequest.propertiesToFetch = ["name", countExpr]
fetchRequest.havingPredicate = NSPredicate(format: "%ld > 1", countVariableExpr)
//let results = try managedContext.execute(fetchRequest) as AnyObject
let searchResults = try managedContext.fetch(fetchRequest)
let resultsDict = searchResults as! [[String: Int32]]
print("(resultsDict)")
} catch {
}
}
let countVariableExpr = NSExpression(forVariable: "Id")
应该用于计数：
let countVariableExpr = NSExpression(forVariable: "count")
并且谓词将进行比较，其中count>1
NSPredicate(format: "%@ > 1", countVariableExpr)
编辑：
您当前正在按名称查找重复记录，如果您想按id查找，则如下所示：
let nameExpr = NSExpression(forKeyPath: "name")
需要更改为：
let idExpression = NSExpression(forKeyPath: "Id")
然后计数表达式将被更改为计数记录id。
NSExpression(forFunction: "count:", arguments: [idExpression])
编辑2:
fetchRequest.propertiesToGroupBy = ["name"]
fetchRequest.propertiesToFetch = ["name", countExpr]
还应更改为获取Id而不是名称，
fetchRequest.propertiesToGroupBy = ["Id"]
fetchRequest.propertiesToFetch = ["Id", countExpr]