ios - 检查是否在特定日期添加了 Realm 数据

Question

如果在特定日期注册了任何锻炼，我正在尝试创建一个查找。

对象类如下所示:

class Workout: Object {

    @objc dynamic var date: Date?
    // List of exercises (to-many relationship)
    var exercises = List<Exercise>()

}

和

class Exercise: Object {

    @objc dynamic var name: String?
    // List of sets (to-many relationship)
    var sets = List<Set>()
    var parentWorkout = LinkingObjects(fromType: Workout.self, property: "exercises")
}

在 Realm 中，我可以看到有一个注册日期为 2019-12-07 19:48:35 +0000;。所以我在我的 viewDidLoad 中添加了一个检查，如下所示:

let nowDate = Date()
func checkIfWorkoutHasBeenRegistered() {// Check if there already exist a workout today
        let realm = try! Realm()

        let todaysWorkouts = realm.objects(Workout.self).filter("date = %@", nowDate)
        if todaysWorkouts.isEmpty {
            print("No workout found")
        } else {
            print("Workout has been created")
        }
    }

但它给了我输出 No workout found，即使我今天注册了锻炼。有什么建议吗？

Answer 1

对于您当前的谓词，您将保存日期和时间与当前日期和时间进行比较，这肯定会有所不同，因为即使是几分之一秒的差异也会使它们不相等。相反，您可能想查看保存的日期是否在某个范围内。例如，如果您想要查看具有发生在“今天”的 date 的所有对象，您可以创建如下谓词:

let startOfDay = Calendar.current.startOfDay(for: Date())
let endOfDay = Calendar.current.date(byAdding: .day, value: 1, to: startOfDay) ?? Date()

let predicate = NSPredicate(format: "date >= %@ && date < %@", startOfDay as NSDate, endOfDay as NSDate)
let todaysWorkouts =  realm.objects(Workout.self).filter(predicate)