iOS按领域按日期分组查看部分

Question

我有领域数据库，其中包含数据和添加此数据的日期。我想解释这一点，并设置日期作为表视图节标题和数据作为每个部分的行数据取决于日期。我知道如何提取，但不知道如何按日期进行分组，并根据日期设置每个部分的数据。谢谢！

Answer 1

您可以使用CoreData作为替代领域，并使用读取的结果控制，使您可以通过一些变种的数据和组排序。

Answer 2

您可以按日期对检索到的Results进行排序，然后在迭代时对它们进行拆分，以便按照分组/层次的方式对其进行访问。

class Person { 
    dynamic var name = "" 
    dynamic var date = NSDate() 
} 

let sortedObjects = realm.objects(Person).sorted("date") 

var lastDate = objects.first?.date 
let calendar = NSCalendar.currentCalendar() 
var lastGroup = [Person]() 
var groups = [[Person]]() 

for element in sortedObjects { 
    let currentDate = element.date 
    let difference = calendar.components([.Year, .Month, .Day], fromDate: lastDate!, toDate: currentDate, options: []) 
    if difference.year > 0 || difference.month > 0 || difference.day > 0 { 
     lastDate = currentDate 
     groups.append(lastGroup) 
     lastGroup = [element] 
    } else { 
     lastGroup.append(element) 
    } 
} 
groups.append(lastGroup) 

注：这样一来，你就需要保持在内存中所有的元素。如果不适合你，根据你的使用情况，你可以只记住索引，而你可以使用它来访问检索到的Results中的元素。

Answer 3

如果有人与雨燕3.0语法战斗：

var lastDate = dateObjects.first?.start 
    let calendar = Calendar.current 
    var lastGroup = [DateObject]() 
    var days = [[DateObject]]() 

    for dateObject in dateObjects { 
     let currentDate = dateObject.start 
     let unitFlags : Set<Calendar.Component> = [.era, .day, .month, .year, .timeZone] 
     let difference = calendar.dateComponents(unitFlags, from: lastDate!, to: currentDate) 

     if difference.year! > 0 || difference.month! > 0 || difference.day! > 0 { 
      lastDate = currentDate 
      days.append(lastGroup) 
      lastGroup = [travelTime] 
     } else { 
      lastGroup.append(dateObject) 
     } 
    } 
    days.append(lastGroup) 

Answer 4

我有完全相同的问题，我需要在一个分区表中显示一种Realm实体，按日期分组，这就是我如何做到的。

包含日期字段

Example类：

final class Appointment: Object { 
    @objc dynamic var id: Int = 0 
    @objc dynamic var date: Date? 
} 

示例代码，将得到所有的对象和他们的部分/结果拆分，通过独特的日期分组：

// (un)safely get an instance of Realm 
let realm = try! Realm() 

// get all the dates 
// note that begginingOfDay is a extension on Date 
// which gives back the beggining of the day of the given Date as a Date 
// we are doing this in order to filter out non-unique dates later 
let dates = self.realm.objects(Appointment.self).toArray().flatMap({ $0.date ?? nil }).map({ $0.beginningOfDay() }) 

// cast it to a Set to make values unique, and back to an Array for further use 
let uniqueDates = Array(Set(dates)) 

let predicates = uniqueDates.map({ date -> NSPredicate in 

    // in order to use Swift's Date with NSPredicate 
    // it must be casted to NSDate 
    let begginingOfDay = date.beginningOfDay() as NSDate 
    let endOfDay = date.endOfDay() as NSDate 

    // create a predicate that checks if the given Date is in between 
    // the beggining of a given Date and the end of the given Date 
    let predicate = NSPredicate(format: "(date >= %@) AND (date <= %@)", begginingOfDay, endOfDay) 

    return predicate 
}) 

// create an array of Results<Appointment>, and then use it to drive your table/collection view 
// I will leave this part to you, depends on your UI implementation 
// personally, I wrap this into another object that contains results, section index, section title, etc. 
// and then I use all of that in my table view's data source methods   
let sectionedResults: [Results<Appointment>] = predicates.map({ predicate -> Results<Appointment> in 
    let results = realm.objects(Appointment.self).filter(predicate) 
    return results 
}) 

您现在应该有一个粗略的想法如何做到这一点，我将把UI实现的细节留给你。