Question

在我的应用程序中，我有一个对象数组的类：EventObjects'，有几个属性，比如'date：NSDate？'和'stuffToDo：String？'从日历数据库中提取的内容。我现在尝试实现的是将所有具有相同日期属性的EventObject放在“class：EventsAtSameDate”的另一个对象中。

class EventsAtSameDate: NSObject
{
   var date:NSDate?
   var eventObjects:NSArray<EventObject>?
}

最后有一个带有EventsAtSameDate的嵌套数组。

var nestedArrayOfEventsAtSameDateObjects: Array<EventsAtSameDate>?

我知道如何使用.filter .sort .sortInPlace等函数搜索和排序数组。但是，如何将数组中的日期相互比较并将它们放在另一个嵌套数组中呢？

Answer 1

您可以实例化一个字典，以便在对EventObject类型的初始数组进行一次迭代时跟踪存在的日期。然后迭代字典以实例化EventsAtSameDate的类并将它们附加到nestedArrayOfEventsAtSameDateObjects: [EventsAtSameDate]

代码看起来像：

var nestedArrayOfEventsAtSameDateObjects = [EventsAtSameDate]()

//instantiate a dictionary that uses Date as the key and an array of EventObject as the associated value
var dictionary = [Date: [EventObject]]()

//iterate through your intial array of EventObjects
for obj in eObjs {
    //check if you have already seen the date in the collection
    if dictionary[obj.date] != nil {
        //if you have - then append it to that date
        dictionary[obj.date]?.append(obj)
        continue
    }
    //otherwise, add it to the dictionary for a check later in the loop
    dictionary[obj.date] = [obj]
}


//then iterate through the dictionary

for (date, eObjs) in dictionary {
    if eObjs.count > 1 {
        let sameDate = EventsAtSameDate()
        sameDate.date = date
        sameDate.eventObjects = eObjs
        nestedArrayOfEventsAtSameDateObjects.append(sameDate)
    }
}

Answer 2

我会按日期对事件数组进行排序，然后迭代它们。检查日期是否比上一个更新，如果是，则创建另一个存储。

class Event {
    var date:Date!
}

class EventsList
{
    var date:Date!
    var events:[Event]!
}

func createEventsLists(sortedEvents: [Event]) -> [EventsList] {
    guard sortedEvents.count > 0 else { return [] }

    var currentEventList = EventsList()
    var result = [currentEventList]
    var lastDate = sortedEvents.first!.date

    for event in sortedEvents {
        let newDate = event.date.compare(lastDate!) != .orderedDescending
        if newDate {
            currentEventList = EventsList()
            result.append(currentEventList)
        }
        currentEventList.events.append(event)
        lastDate = event.date
    }
    return result
}

比较Array中的对象并在单独的新对象中放置相等的值

2 个答案: