iOS: UICollectionView sections from array with dates - ios

Question

I have an array of Person. The Person object has many fields between them inscriptionDate (a timestamp). I have to create a collectionView from this array but using sections. Every section has a header that is inscriptionDate as a date having this format dd/mm/yyyy. I have to sort the array by inscriptionDate but without time (only the format dd/mm/yyyy) in order to load the data in the collectionView (taking into consideration the sections). I have found from another question this solution. But how can I sort the array before doing this? How can I use this:
order = NSCalendar.currentCalendar().compareDate(now, toDate: olderDate,
toUnitGranularity: .Day)
in my case?

Answer 1

I agree with #Vasilii Muravev, you will need to clean your timestamp object first, either using extensions or functions. Timestamp isn't a valid Swift object btw, unless that is a custom class you created.
Then you can create a dictionary for your dataSource. I will use #Vasilii Muravev's extension:
//var myKeys : [Date] = []
let sortedPeople = persons.sorted { $0.inscriptionDate.noTime() < $1.inscriptionDate.noTime() }
//break your array into a dictionary([Date : [Person]])
//personsSortedByDateInSections : [Date : [Person]] = [:]
for person in sortedPeople {
if personsSortedByDateInSections[person.inscriptionDate] != nil {
personsSortedByDateInSections[person.inscriptionDate]!.append(person)
} else {
personsSortedByDateInSections[person.inscriptionDate] = [person]
}
}
myKeys = setKeyArray(personSortedByDateInSections.keys)
that will give you a dictionary object with all of your Person objects grouped(sectioned) by their inscriptionDate. Then you will just need to fill out your collectionView delegate and datasource methods.
override func numberOfSections(in: UICollectionView) -> Int {
return myKeys.count
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return personsSortedByDateInSections[myKeys[section]].count
}
UPDATE:
As stated in your comment there is a issue with grabbing a array of the keys with swift dictionaries(I don't think swift dictionaries had this issue in earlier version? I could be wrong)....anyway to workaround this I have used this function to set a class variable for the 'keyArray'.:
fileprivate func setKeysArray(_ keys: LazyMapCollection<Dictionary<Date, [Person]>, String) -> [Date]{
var keysArray = [Date]()
for key in keys {
keysArray.append(key)
}
return keysArray
}

Answer 2

First, you'll need to clean timestamp before the sorting. You can do that by using Calendar and Date extension:
extension Date {
func noTime() -> Date! {
let components = Calendar.current.dateComponents([.day, .month, .year], from: self)
return Calendar.current.date(from: components)
}
}
Then you'll just need to sort your array by date without time:
let sortedByDate = persons.sorted { $0.inscriptionDate.noTime() < $1.inscriptionDate.noTime() }
Note. Be careful with compareDate function of Calendar, since it comparing only specific component. If in this example: NSCalendar.currentCalendar().compareDate(now, toDate: olderDate, toUnitGranularity: .Day) you'll have same days in different months, the comparing result will show that dates are equal.

Answer 3

Assuming your inscriptionDate is a Date, why can't you sort on that? Since Date conforms to Comparable all you need is
let sortedByDate = persons.sorted { $0.inscriptionDate < $1.inscriptionDate }

Answer 4

I wright a code for you I thing this code useful for you.
//
// ViewController.swift
// sortData
//
// Created by Bijender singh on 26/01/18.
// Copyright © 2018 Bijender singh. All rights reserved.
//
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
override func viewDidAppear(_ animated: Bool) {
let myDataArray = NSMutableArray()
var myDataDic = NSMutableDictionary()
myDataDic.setValue("Bijender", forKey: "name")
myDataDic.setValue("1516965600", forKey: "date")
myDataArray.add(myDataDic)
myDataDic = NSMutableDictionary()
myDataDic.setValue("ben", forKey: "name")
myDataDic.setValue("1516965540", forKey: "date")
myDataArray.add(myDataDic)
myDataDic = NSMutableDictionary()
myDataDic.setValue("Deke", forKey: "name")
myDataDic.setValue("1516842180", forKey: "date")
myDataArray.add(myDataDic)
myDataDic = NSMutableDictionary()
myDataDic.setValue("Veer", forKey: "name")
myDataDic.setValue("1516842000", forKey: "date")
myDataArray.add(myDataDic)
myDataDic = NSMutableDictionary()
myDataDic.setValue("Ashfaq", forKey: "name")
myDataDic.setValue("1515981900", forKey: "date")
myDataArray.add(myDataDic)
print(myDataArray)
let sortedArray = self.sortDataWithDate(arrayData: myDataArray)
// sortedArray contane array which contan same date array
// you can use it according to you
// sortedArray.count is total diffrent dates in your array
// and (sortedArray.count[i] as! NSArray).count give you count of data of that date (0 < i < sortedArray.count)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func sortDataWithDate(arrayData : NSArray) -> NSArray {
// var chat: [ChatMessage]!
let returnArray = NSMutableArray()
var subArray = NSMutableArray()
let arrayDate = NSMutableArray()
for i in 0 ..< arrayData.count {
let msgDate = self.timeStampToDate(_timestamp: ((arrayData[i] as! NSDictionary).object(forKey: "date") as! String), _dateFormat: "dd/MM/yyyy")
print("dddt \(msgDate)")
// print("date array \(arrayDate) $$ msgDate \(msgDate)")
if arrayDate.contains(msgDate) {
subArray.add(arrayData[i])
}
else{
arrayDate.add(msgDate)
if arrayDate.count > 1 {
returnArray.add(subArray)
}
subArray = NSMutableArray()
subArray.add(arrayData[i])
}
}
if subArray != nil {
returnArray.add(subArray)
}
print(returnArray)
return returnArray
}
func timeStampToDate(_timestamp : String, _dateFormat : String) -> String{
// _dateFormat = "yyyy-MM-dd HH:mm:ss.SSSS"
var date = Date(timeIntervalSince1970: TimeInterval(_timestamp)!)
date += TimeInterval(Int(TimeZone.current.secondsFromGMT()) as NSNumber)
let dateFormatter = DateFormatter()
dateFormatter.timeZone = TimeZone(abbreviation: "GMT") //Set timezone that you want
dateFormatter.locale = NSLocale.current
dateFormatter.dateFormat = _dateFormat
let strDate = dateFormatter.string(from: date)
return strDate
}
}
In this code I insert array as hard coded
(
{
date = 1516965600;
name = Bijender;
},
{
date = 1516965540;
name = ben;
},
{
date = 1516842180;
name = Deke;
},
{
date = 1516842000;
name = Veer;
},
{
date = 1515981900;
name = Ashfaq;
}
)
And out put array is
(
(
{
date = 1516965600;
name = Bijender;
},
{
date = 1516965540;
name = ben;
}
),
(
{
date = 1516842180;
name = Deke;
},
{
date = 1516842000;
name = Veer;
}
),
(
{
date = 1515981900;
name = Ashfaq;
}
)
)