ios - 解析快速子类关系

Question

我正在将解析实现到我的 swift 应用程序中。我有子类，其中一个子类有一个成员对象，它是另一个解析子类。当我尝试访问该对象时，应用程序收到“由于未捕获的异常‘NSInvalidArgumentException’而终止应用程序，原因:‘-[fve.Workout sets]:无法识别的选择器发送到实例 0x1740d0d10’”

知道如何访问本身是 PBObject 子类的 PFObject 子类的元素吗？

这是我声明对象的方式:

class Workout: PFObject, PFSubclassing {
    @NSManaged var date: NSDate
    @NSManaged var workoutTime: Int
    @NSManaged var sets: [ExerciseSet]
    ...
}

class ExerciseSet: PFObject, PFSubclassing {
    @NSManaged var exercise: Exercise
    @NSManaged var sets: [SingleSet]
    ...
}

当我尝试访问该字段时，这会导致崩溃:

for workout in historicalWorkoutsParse {
    println("workout \(workout)")
    let exerciseSets = workout.sets
    println("exerciseSet: \(exerciseSets)")
}

即使我确实看到对象中存在数据:

workout <Workout: 0x1740cf8f0, objectId: A3218Oxiuh, localId: (null)> {
    date = "2015-09-05 19:39:43 +0000";
    sets =     (
        "<ExerciseSet: 0x1740cf960, objectId: V54sAUKSMf, localId: (null)>"
    );
    user = "<PFUser: 0x174109240, objectId: LbeTd8GqwU, localId: (null)>";
    workoutTime = 0;
}

谢谢!

Answer 1

如果您使用PFSubclassing，您需要调用registerSubclass在你可以使用类(class)之前。它还必须在 Parse.setApplicationId 调用之前完成:

Workout.registerSubclass()
ExerciseSet.registerSubclass
//Parse.setApplicationId