Alphabetical sections in table table view in swift - ios

Question

I have a list of names sorted alphabetically, and now I want display these names in a table view. I'm struggling with grouping these names for each letter.
My code looks like this:
let sections:Array<AnyObject> = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"]
var usernames = [String]()
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell{
let cellID = "cell"
let cell: UITableViewCell = self.tv.dequeueReusableCellWithIdentifier(cellID) as UITableViewCell
cell.textLabel?.text = usernames[indexPath.row]
return cell
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int{
return usernames.count
}
func numberOfSectionsInTableView(tableView: UITableView) -> Int{
return 26
}
func sectionIndexTitlesForTableView(tableView: UITableView) -> [AnyObject]!{
return self.sections
}
func tableView(tableView: UITableView,
sectionForSectionIndexTitle title: String,
atIndex index: Int) -> Int{
return index
}
func tableView(tableView: UITableView,
titleForHeaderInSection section: Int) -> String?{
return self.sections[section] as? String
}
and it all works pretty good except for the grouping which makes my table view end up like this:
So I know you should be able to use the filtered function in an Array, but I did not understand how to implement it.
Any suggestions on how to proceed would be appreciated.

Answer 1

In Swift 4 Dictionary(grouping:by:) was introduced to group a sequence to a dictionary by an arbitrary predicate.
This example maps the grouped dictionary to a custom struct Section
struct Section {
let letter : String
let names : [String]
}
...
let usernames = ["John", "Nancy", "James", "Jenna", "Sue", "Eric", "Sam"]
var sections = [Section]()
override func viewDidLoad() {
super.viewDidLoad()
// group the array to ["N": ["Nancy"], "S": ["Sue", "Sam"], "J": ["John", "James", "Jenna"], "E": ["Eric"]]
let groupedDictionary = Dictionary(grouping: usernames, by: {String($0.prefix(1))})
// get the keys and sort them
let keys = groupedDictionary.keys.sorted()
// map the sorted keys to a struct
sections = keys.map{ Section(letter: $0, names: groupedDictionary[$0]!.sorted()) }
self.tableView.reloadData()
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cellID = "cell"
let cell = tableView.dequeueReusableCell(withIdentifier: cellID, for: indexPath)
let section = sections[indexPath.section]
let username = section.names[indexPath.row]
cell.textLabel?.text = username
return cell
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return sections[section].names.count
}
func numberOfSections(in tableView: UITableView) -> Int {
return sections.count
}
func sectionIndexTitles(for tableView: UITableView) -> [String]? {
return sections.map{$0.letter}
}
func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
return sections[section].letter
}

Answer 2

This is how I recently implemented sorted list in a tableView in Swift programmatically,
import UIKit
class BreedController: UITableViewController{
var breeds = ["A": ["Affenpoo", "Affenpug", "Affenshire", "Affenwich", "Afghan Collie", "Afghan Hound"], "B": ["Bagle Hound", "Boxer"]]
struct Objects {
var sectionName : String!
var sectionObjects : [String]!
}
var objectArray = [Objects]()
override func viewDidLoad() {
super.viewDidLoad()
tableView.delegate = self
tableView.dataSource = self
tableView.registerClass(UITableViewCell.classForCoder(), forCellReuseIdentifier: "Cell")
// SORTING [SINCE A DICTIONARY IS AN UNSORTED LIST]
var sortedBreeds = sorted(breeds) { $0.0 < $1.0 }
for (key, value) in sortedBreeds {
println("\(key) -> \(value)")
objectArray.append(Objects(sectionName: key, sectionObjects: value))
}
}
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return objectArray.count
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return objectArray[section].sectionObjects.count
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as! UITableViewCell
// SETTING UP YOUR CELL
cell.textLabel?.text = objectArray[indexPath.section].sectionObjects[indexPath.row]
return cell
}
override func tableView(tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
return objectArray[section].sectionName
}
}

Answer 3

Download CountryList Json file and put in side your project
https://gist.github.com/keeguon/2310008
var json = NSArray()
var arr_name = NSArray()
var arrIndexSection : NSArray = ["A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"]
override func viewDidLoad() {
let path = Bundle.main.path(forResource: "countries", ofType: "json")
let data = NSData(contentsOfFile: path! )
json = (try! JSONSerialization.jsonObject(with: data as! Data, options: JSONSerialization.ReadingOptions.mutableContainers)) as! NSArray
arr_name = json.value(forKey: "name") as! NSArray;
tableview.reloadData()
super.viewDidLoad()
}
// Side List in tableview
public func numberOfSections(in tableView: UITableView) -> Int {
return 26
}
public func sectionIndexTitles(for tableView: UITableView) -> [String]? {
return self.arrIndexSection as? [String] //Side Section title
}
public func tableView(_ tableView: UITableView, sectionForSectionIndexTitle title: String, at index: Int) -> Int
{
return index
}
public func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
return arrIndexSection.object(at: section) as? String
}
// number of rows in table view
public func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int
{
let predicate = NSPredicate(format: "SELF beginswith[c] %#", arrIndexSection.object(at: section) as! CVarArg)
let arrContacts = (arr_name as NSArray).filtered(using: predicate)
return arrContacts.count;
}
public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell
{
let cell : TableViewCell=self.tableview.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! TableViewCell
let predicate = NSPredicate(format: "SELF beginswith[c] %#", arrIndexSection.object(at: indexPath.section) as! CVarArg)
let arrContacts = (arr_name as NSArray).filtered(using: predicate) as NSArray
cell.textLabel?.text = arrContacts.object(at: indexPath.row) as? String
return cell
}

Answer 4

You can put your arrays with names into dictionary with letter keys.
For example
var names = ["a": ["and", "array"], "b": ["bit", "boring"]]; // dictionary with arrays setted for letter keys
then you need to access values in your dictionary in the next way
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int{
return names[usernames[section]].count; // maybe here is needed to convert result of names[...] to NSArray before you can access count property
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell{
let cellID = "cell"
let cell: UITableViewCell = self.tv.dequeueReusableCellWithIdentifier(cellID) as UITableViewCell
cell.textLabel?.text = names[usernames[indexPath.section]][indexPath.row]; // here you access elements in arrray which is stored in names dictionary for usernames[indexPath.section] key
return cell
}

Answer 5

In case, if your data array is not predefined, here's a way to achieve the same thing.
Let's say our class is ViewController.
class ViewController: UIViewController {
var contactDictionary = [String: [Contact]]() //Contact is a model, it has firstName and lastName properties
var keys = [String]()
var alphabets = (97...122).map { "\(Character(UnicodeScalar.init($0)))" }.map { $0.uppercased() } //Populating alphabets
... // other properties
override func viewDidLoad() {
super.viewDidLoad()
//set delegate and register cell for your tableView
self.setContacts()
}
private func setContacts() {
//Loop through your array, take the firstName, and the first character of that string.
//Check the uppercase value of that character, if it's an alphabet or not, otherwise, we'd place "#" for the names starting with a number in the header.
var temp = [String: [Contact]]() //A temporary dictionary
for contact in self.contacts {
if let firstName = contact.firstName, !firstName.isEmpty { //In my case, the firstName is an optional string
let firstChar = "\(firstName.first!)".uppercased()
if alphabets.contains(firstChar) {
var array = temp[firstChar] ?? []
array.append(contact)
temp[firstChar] = array
} else {
var array = temp["#"] ?? []
array.append(contact)
temp["#"] = array
}
}
}
self.keys = Array(temp.keys).sorted() //Populating and sorting all the keys alphabetically.
for key in self.keys { self.contactDictionary[key] = temp[key] }
//reload table
}
}
extension: ViewController: UITableViewDelegate, UITableViewDataSource {
func numberOfSections(in tableView: UITableView) -> Int {
return self.contactDictionary.count
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return self.contactDictionary[keys[section]]?.count ?? 0
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let key = self.keys[indexPath.section]
let cell: //dequeue your cell here.
if let row = self.contactDictionary[key]?[indexPath.row] {
cell.display(with: row) //Bind your cell's outlets with the properties
return cell
}
//handle error
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let key = self.keys[indexPath.section]
if let row = self.contactDictionary[key]?[indexPath.row] {
//handle selection.
}
}
func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? { //You can use viewForHeaderInSection either.
return self.keys[section]
}
}

Answer 6

var frndsName = ["Vanitha","Ilakkiya","Parveen","Divya","Seetha","Madhavi","Ashwini","Sangeetha","Swathi","Don","Priyanka","Tamilselvi","Premlatha","Prashanthi","Rekha","Ajitha","Praveena","Indhusree","Nisha","Priya","Lavanya","Sandhiya","Gejalakshmi","Pavithra","Abinaya"]
let sections = ["*","A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z","#"]
var dividedArray:NSMutableArray = []
override func viewDidLoad() {
super.viewDidLoad()
for i in sections{
let dummyArray:NSMutableArray = []
for j in frndsName{
if i.first! == j.first! {
dummyArray.add(j)
}
}
dividedArray.add(dummyArray)
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
func numberOfSections(in tableView: UITableView) -> Int {
return 26
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return (dividedArray[section] as! NSMutableArray).count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell")
let dummyArray = dividedArray[indexPath.section] as! NSMutableArray
cell?.textLabel?.text = dummyArray[indexPath.row] as? String
return cell!
}
func sectionIndexTitles(for tableView: UITableView) -> [String]? {
return self.sections
}
func tableView(_ tableView: UITableView, sectionForSectionIndexTitle title: String, at index: Int) -> Int {
return index
}
internal func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
return self.sections[section] as String
}
}

Answer 7

var nameList = ["Abc","Bbc","Cbc",......]//whatever it is
var arrNameList = [[nameList]]()
var str = String()
override func viewDidLoad() {
str = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
for i : Int in 0 ..< (str.count) {
var arr = [nameList]()
for j : Int in 0 ..< nameList.count {
let name = nameList[j]
let index = str.index(str.startIndex, offsetBy: i)
let char = str[index]
if name.first == char {
arr.append(name)
}
}
arrNameList.append(arr)
}
}
func numberOfSections(in tableView: UITableView) -> Int {
return arrNameList.count
}
func tableView(_ tableView: UITableView, titleForHeaderInSection
section: Int) -> String? {
let index = str.index(str.startIndex, offsetBy: section)
let char = str[index]
return char
}
func tableView(_ tableView: UITableView, numberOfRowsInSection
section: Int) -> Int {
return arrNameList[section].count
}
func tableView(_ tableView: UITableView, heightForHeaderInSection
section: Int) -> CGFloat {
return 40
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath:
IndexPath) -> CGFloat {
return 40
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath:
IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell",
for: indexPath) as! NameListTableViewCell
let name = arrNameList[indexPath.section][indexPath.row]
cell.nameLbl.text = name
cell.selectionStyle = .none
return cell
}