Question

我想弄清楚为什么我的数组会动态更新？

我有以下课程

class LocationData {
   var address: String = ""
   var city: String = ""
   var deviceName: String = ""
   var deviceId: String = ""
   var state: String = ""
}

然后我有以下功能

func fetchLocationItems(sortByKey1: String, sortByKey2: String, deviceID: String, isAsecending: Bool) -> [LocationData]{

    var locationObjectArray = [LocationData]()

    var locationData = LocationData()
    let context: NSManagedObjectContext = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext
    do {
        let request = NSFetchRequest(entityName: "Location")
        let sortDescriptor1 = NSSortDescriptor(key: sortByKey1, ascending: isAsecending)
        let sortDescriptor2 = NSSortDescriptor(key: sortByKey2, ascending: isAsecending)
        request.sortDescriptors = [sortDescriptor1, sortDescriptor2]
        let results = try locationContext.executeFetchRequest(request)
        var count = 0
        if results.count > 0 {
            for item in results as! [NSManagedObject] {
                if item.valueForKey("deviceID")  as! String == deviceID {
                   locationData.deviceId  = item.valueForKey("deviceID")  as! String  
                   locationData.address = item.valueForKey("address") as! String
                   locationData.city = item.valueForKey("city") as! String
                   locationData.state = item.valueForKey("state") as! String
                   locationData.deviceName = item.valueForKey("deviceName") as! String
                   locationObjectArray.insert(locationData, atIndex: count)
                   count++
                }
             }
            //try context.save()
        }

    } catch {
        print("There was error getting data")
    }
    return locationObjectArray

}

所以我在coredata有4条记录。第一次通过＆＃34; for item loop＆＃34;，将locationDate插入到locationObjectArry

第二次循环时，位于索引0的locationObjectArray中的值将使用新值进行更新，例如

locationData.deviceId  = item.valueForKey("deviceID")  as! String  
locationData.address = item.valueForKey("address") as! String

等等。

所以在循环结束时，locationObjectArray [0..4]的值都与最后一条记录的值相同。

知道可能是什么问题吗？

Answer 1

因为你的对象在每个循环中都不是init新的。所以对象仍然是相同的

尝试：

for item in results as! [NSManagedObject] {
    if item.valueForKey("deviceID")  as! String == deviceID {
        // init new LocationData
        var locationData = LocationData()
        locationData.deviceId  = item.valueForKey("deviceID")  as! String
        locationData.address = item.valueForKey("address") as! String
        locationData.city = item.valueForKey("city") as! String
        locationData.state = item.valueForKey("state") as! String
        locationData.deviceName = item.valueForKey("deviceName") as! String
        locationObjectArray.insert(locationData, atIndex: count)
        count++
    }
}

当值发生变化时，数组会更新

1 个答案: