SwiftData模型实例创建速度极慢，如何优化大规模数据处理？

问题背景 #

在处理包含3万+行、总计约23万个元素的CSV文件时，使用SwiftData创建模型实例并存储的总耗时约90秒，而此前使用CoreData完成相同操作仅需3秒。经排查，性能瓶颈完全源于SwiftData模型实例的创建过程。

苹果官方回复 #

提交代码级支持（DTS）工单并提供测试项目与数据后，苹果官方反馈：

针对反馈编号#FB13432637，DTS无法提供解决方案，该问题仍在调查中，请通过bug报告持续跟踪。

验证测试 #

为确认问题根源，执行了以下测试步骤：

• 移除所有SwiftData保存操作，仅保留模型对象创建逻辑
• 创建去掉@Model宏的SwiftData模型类副本
• 将isAutosaveEnabled设为false

测试结果显示，使用无@Model宏的副本类执行循环仅需3秒，由此确定是@Model宏带来的实例创建开销导致了30倍的耗时增加。

代码对比 #

带@Model的SwiftData代码（耗时90+秒） #

@Model
class TimetableData {
    
    var arrivalTime : Int = 0
    var departureTime: Int = 0
    var departureRoute : Int = 0
    var directionOfTravel : Int = 0
    var dutyNumber : Int = 0
    var facilityIdentifier : String = ""
    var locationType : String = ""
    var mode : String = ""
    var nonStopStatus : Int = 0
    var recordIdentifier : String = ""
    var timetableIdentifier : Int = 0
    var trainNumber : String = ""
    var tripNumber : Int = 0
    var tripStartSite : String = ""
    var uniqueLocationCode : String = ""
    
    init(arrivalTime: Int = 0, departureTime: Int = 0, departureRoute: Int = 0, directionOfTravel: Int = 0, dutyNumber: Int = 0, facilityIdentifier: String = "", locationType: String = "", mode: String = "", nonStopStatus: Int = 0, recordIdentifier: String = "", timetableIdentifier: Int = 0, trainNumber: String = "", tripNumber: Int = 0, tripStartSite: String = "", uniqueLocationCode: String = "") {
        // 注：原代码中`self.name = name`存在未定义变量问题，疑似笔误
        self.arrivalTime = arrivalTime
        self.departureTime = departureTime
        self.departureRoute = departureRoute
        self.directionOfTravel = directionOfTravel
        self.dutyNumber = dutyNumber
        self.facilityIdentifier = facilityIdentifier
        self.locationType = locationType
        self.mode = mode
        self.nonStopStatus = nonStopStatus
        self.recordIdentifier = recordIdentifier
        self.timetableIdentifier = timetableIdentifier
        self.trainNumber = trainNumber
        self.tripNumber = tripNumber
        self.tripStartSite = tripStartSite
        self.uniqueLocationCode = uniqueLocationCode
    }
}

for line in CSVFile {
    var columnValue = line.components(separatedBy: ",")
    
    let timeTableDataEntry = TimetableData(
        arrivalTime: Int(columnValue[0])!,
        departureTime: Int(columnValue[1])!,
        departureRoute: Int(columnValue[2])!,
        directionOfTravel: Int(columnValue[3])!,
        dutyNumber: Int(columnValue[4])!,
        facilityIdentifier: columnValue[5],
        locationType: columnValue[6],
        mode: columnValue[7],
        nonStopStatus: Int(columnValue[8])!,
        recordIdentifier: columnValue[9],
        timetableIdentifier: Int(columnValue[10])!,
        trainNumber: columnValue[11],
        tripNumber: Int(columnValue[12])!,
        tripStartSite: columnValue[13],
        uniqueLocationCode: columnValue[14]
    )
}

无@Model的测试代码（耗时约3秒） #

class TimetableDataForTesting {
    
    var arrivalTime : Int = 0
    var departureTime: Int = 0
    var departureRoute : Int = 0
    var directionOfTravel : Int = 0
    var dutyNumber : Int = 0
    var facilityIdentifier : String = ""
    var locationType : String = ""
    var mode : String = ""
    var nonStopStatus : Int = 0
    var recordIdentifier : String = ""
    var timetableIdentifier : Int = 0
    var trainNumber : String = ""
    var tripNumber : Int = 0
    var tripStartSite : String = ""
    var uniqueLocationCode : String = ""
    
    init(arrivalTime: Int = 0, departureTime: Int = 0, departureRoute: Int = 0, directionOfTravel: Int = 0, dutyNumber: Int = 0, facilityIdentifier: String = "", locationType: String = "", mode: String = "", nonStopStatus: Int = 0, recordIdentifier: String = "", timetableIdentifier: Int = 0, trainNumber: String = "", tripNumber: Int = 0, tripStartSite: String = "", uniqueLocationCode: String = "") {
        // 注：原代码中`self.name = name`存在未定义变量问题，疑似笔误
        self.arrivalTime = arrivalTime
        self.departureTime = departureTime
        self.departureRoute = departureRoute
        self.directionOfTravel = directionOfTravel
        self.dutyNumber = dutyNumber
        self.facilityIdentifier = facilityIdentifier
        self.locationType = locationType
        self.mode = mode
        self.nonStopStatus = nonStopStatus
        self.recordIdentifier = recordIdentifier
        self.timetableIdentifier = timetableIdentifier
        self.trainNumber = trainNumber
        self.tripNumber = tripNumber
        self.tripStartSite = tripStartSite
        self.uniqueLocationCode = uniqueLocationCode
    }
}

for line in CSVFile {
    var columnValue = line.components(separatedBy: ",")
    
    let timeTableDataEntry = TimetableDataForTesting(
        arrivalTime: Int(columnValue[0])!,
        departureTime: Int(columnValue[1])!,
        departureRoute: Int(columnValue[2])!,
        directionOfTravel: Int(columnValue[3])!,
        dutyNumber: Int(columnValue[4])!,
        facilityIdentifier: columnValue[5],
        locationType: columnValue[6],
        mode: columnValue[7],
        nonStopStatus: Int(columnValue[8])!,
        recordIdentifier: columnValue[9],
        timetableIdentifier: Int(columnValue[10])!,
        trainNumber: columnValue[11],
        tripNumber: Int(columnValue[12])!,
        tripStartSite: columnValue[13],
        uniqueLocationCode: columnValue[14]
    )
}

内容的提问来源于stack exchange，提问作者RyanTCB