Question

我正在进行潜水应用程序，其中一项功能是将潜水等级存储为CoreData中的两倍。界面应该能够从coredata对象中检索double值，然后在屏幕上显示。但是，我从代码中得到的问题是从对象返回的double非常小（e的功率为-315）。我不知道为什么会这样。

if let dives = self.diveSite?.logged_dives {
            for dive in dives {
                print("######### dive site info ########")
                rating = Double(dive.rating) + rating
                print(dive)
                print("raw dive site rating is \(dive.rating)")
                print("dive rating is \(rating)")
            }
        } else {
            print("no logged_dives")
        }

这是在控制台上打印出来的内容......

######### dive site info ########
<ScubaDoo.DiveLog: 0x7fe9ea02cbc0> (entity: DiveLog; id: 0xd000000000180002 <x-coredata://2B6F1E6F-1EDA-4910-91FA-0593E05F9EB2/DiveLog/p6> ; data: {
    current = nil;
    depth = 0;
    "dive_at" = "0xd000000000140000 <x-coredata://2B6F1E6F-1EDA-4910-91FA-0593E05F9EB2/DiveSite/p5>";
    id = nil;
    latitude = 0;
    longitude = 0;
    rating = 5;
    "sea_condition" = nil;
    temperature = 0;
    time = nil;
    weather = nil;
})
raw dive site rating is 5.35679601527854e-315
dive rating is 1.06203402623994e-314
dive site rating is 1.06203402623994e-314

swift中的DiveLog对象如下所示。我真的对此没有任何线索。在获得评级属性时似乎有些东西是不受约束的？

import Foundation
import CoreData

extension DiveLog {

    @NSManaged var time: NSDate?
    @NSManaged var latitude: NSNumber?
    @NSManaged var id: String?
    @NSManaged var rating: NSNumber?
    @NSManaged var depth: NSNumber?
    @NSManaged var temperature: NSNumber?
    @NSManaged var weather: String?
    @NSManaged var current: String?
    @NSManaged var sea_condition: String?
    @NSManaged var longitude: NSNumber?
    @NSManaged var dive_at: DiveSite?

}

Answer 1

不确定刚刚发生了什么，但我升级到了XCode 7.3，并且问题得到解决。我猜这个问题出在IDE本身？

CoreData的Double返回非常小的数字

1 个答案: