Now that I know that MVC can help do better code, I want to make my SettingsTableViewController class conform to it.
SettingsTableViewController is a subclass of UITableViewController. It is linked to a storyboard scene that contains a UITableView with two cells (grouped tableView style, prototype cells). The first cell has a right detail style (textLabel and detailTextLabel), the second cell has a custom style and displays a UIPickerView inside of its contentView.
When it appears on screen, SettingsTableViewController displays only the first cell. When I click on this cell, the second cell containing a UIPickerView appears. If I click again on the first cell, the second cell disappears.
The detailtextLabel of the first row displays an integer saved in NSUserDefaults. The pickerView of the second cell is linked to an array of integers. When I select a row in the pickerView, it saves the row's related integer in NSUserDefaults and updates the detailtextLabel of the first cell.
The image below may help understand the way it works:
Before knowing the concept of MVC, I was able to write the following code to make the previous explanation work:
class SettingsTableViewController: UITableViewController, UIPickerViewDelegate, UIPickerViewDataSource {
let itemsArray = [5, 10, 15]
var pickerIndexPath: NSIndexPath? //acts like a Bool and allows to hide or show cell with identifier "pickerCell"
var numberOfItems: Int {
get {
return NSUserDefaults.standardUserDefaults().integerForKey("NumberOfItems")
}
set {
NSUserDefaults.standardUserDefaults().setInteger(newValue, forKey: "NumberOfItems")
NSUserDefaults.standardUserDefaults().synchronize()
}
}
override func viewDidLoad() {
super.viewDidLoad()
title = "Settings"
//Init numberOfItems
if numberOfItems == 0 {
numberOfItems = 5
}
//Autoset cells height (iOS8)
tableView.rowHeight = UITableViewAutomaticDimension
tableView.estimatedRowHeight = 44
}
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 1
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
//If pickerIndexPath is nil, show only one cell
return pickerIndexPath == nil ? 1 : 2
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
var cell: UITableViewCell!
if indexPath.row == 0 {
cell = tableView.dequeueReusableCellWithIdentifier("RightDetailCell", forIndexPath: indexPath) as UITableViewCell
cell.textLabel?.text = "Items"
cell.detailTextLabel?.text = "\(numberOfItems)"
} else {
cell = tableView.dequeueReusableCellWithIdentifier("PickerCell", forIndexPath: indexPath) as UITableViewCell
cell.selectionStyle = .None
//Set pickerView inside cell
let picker = cell.viewWithTag(1) as UIPickerView
picker.delegate = self
picker.dataSource = self
//Set the middle row in picker according to numberOfItems
if let index = find(itemsArray, numberOfItems) {
picker.selectRow(index, inComponent: 0, animated: false)
}
}
return cell
}
override func tableView(tableView: UITableView, willSelectRowAtIndexPath indexPath: NSIndexPath) -> NSIndexPath? {
switch indexPath {
case NSIndexPath(forRow: 1, inSection: 0):
return nil
default:
return indexPath
}
}
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
tableView.deselectRowAtIndexPath(indexPath, animated: true)
if indexPath == NSIndexPath(forRow: 0, inSection: 0) {
//Show or hide pickerCell
if pickerIndexPath == nil {
tableView.beginUpdates()
pickerIndexPath = NSIndexPath(forRow: 1, inSection: 0)
tableView.insertRowsAtIndexPaths([pickerIndexPath!], withRowAnimation: .Fade)
tableView.endUpdates()
} else {
tableView.beginUpdates()
tableView.deleteRowsAtIndexPaths([pickerIndexPath!], withRowAnimation: .Fade)
pickerIndexPath = nil
tableView.endUpdates()
}
}
}
//MARK: UIPickerViewDataSource
func numberOfComponentsInPickerView(_: UIPickerView) -> Int {
return 1
}
func pickerView(_: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return itemsArray.count
}
//MARK: UIPickerViewDelegate
func pickerView(_: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String! {
return "\(itemsArray[row]) items"
}
func pickerView(_: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
if pickerIndexPath != nil {
//save new value in NSUserDefaults
numberOfItems = itemsArray[row]
//update first cell
let index = NSIndexPath(forRow: pickerIndexPath!.row - 1, inSection: 0)
tableView.reloadRowsAtIndexPaths([index], withRowAnimation: .Fade)
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
}
Then, in order to conform to MVC design pattern, I replaced the previous code with the following:
SettingsTableViewController:
class SettingsTableViewController: UITableViewController {
let dataSource = DataSource()
override func viewDidLoad() {
super.viewDidLoad()
title = "Settings"
//Autoset cells height (iOS8)
tableView.rowHeight = UITableViewAutomaticDimension
tableView.estimatedRowHeight = 44
}
override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 1
}
override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
//If pickerIndexPath is nil, show only one cell
return dataSource.pickerIndexPath == nil ? 1 : 2
}
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
if indexPath.row == 0 {
let cell = tableView.dequeueReusableCellWithIdentifier("LabelCell", forIndexPath: indexPath) as LabelCell
cell.dataSource = dataSource
return cell
} else {
let cell = tableView.dequeueReusableCellWithIdentifier("PickerCell", forIndexPath: indexPath) as PickerCell
cell.dataSource = dataSource
return cell
}
}
override func tableView(tableView: UITableView, willSelectRowAtIndexPath indexPath: NSIndexPath) -> NSIndexPath? {
switch indexPath {
case NSIndexPath(forRow: 1, inSection: 0):
return nil
default:
return indexPath
}
}
override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
tableView.deselectRowAtIndexPath(indexPath, animated: true)
if indexPath == NSIndexPath(forRow: 0, inSection: 0) {
//Show or hide pickerCell
tableView.beginUpdates()
if dataSource.pickerIndexPath == nil {
dataSource.pickerIndexPath = NSIndexPath(forRow: indexPath.row + 1, inSection: 0)
tableView.insertRowsAtIndexPaths([dataSource.pickerIndexPath!], withRowAnimation: .Fade)
} else {
tableView.deleteRowsAtIndexPaths([dataSource.pickerIndexPath!], withRowAnimation: .Fade)
dataSource.pickerIndexPath = nil
}
tableView.endUpdates()
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
}
LabelCell:
//Global context variable
private var observerContext = 0
class LabelCell: UITableViewCell {
var dataSource: DataSource? {
willSet {
disconnectFromModel()
}
didSet {
connectToModel()
update()
}
}
private func disconnectFromModel() {
dataSource?.removeObserver(self, forKeyPath: "numberOfItems", context: &observerContext)
}
private func connectToModel() {
dataSource?.addObserver(self, forKeyPath: "numberOfItems", options: NSKeyValueObservingOptions(), context: &observerContext)
}
override func observeValueForKeyPath(keyPath: String!, ofObject object: AnyObject!, change: [NSObject : AnyObject]!, context: UnsafeMutablePointer<Void>) {
if context == &observerContext {
update()
} else {
super.observeValueForKeyPath(keyPath, ofObject: object, change: change, context: context)
}
}
private func update() {
if let model = dataSource {
textLabel?.text = "Items"
detailTextLabel?.text = "\(model.numberOfItems)"
}
}
deinit {
disconnectFromModel()
}
}
PickerCell:
class PickerCell: UITableViewCell, UIPickerViewDelegate, UIPickerViewDataSource {
@IBOutlet weak var picker: UIPickerView!
var dataSource: DataSource? {
didSet {
update()
}
}
override func awakeFromNib() {
super.awakeFromNib()
selectionStyle = .None
picker.delegate = self
picker.dataSource = self
}
func update() {
if let dataSource = dataSource {
if let index = find(dataSource.itemsArray, dataSource.inspectionPref) {
picker.selectRow(index, inComponent: 0, animated: false)
}
}
}
//MARK: UIPickerViewDataSource
func numberOfComponentsInPickerView(_: UIPickerView) -> Int {
return 1
}
func pickerView(_: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return dataSource!.itemsArray.count
}
//MARK: UIPickerViewDelegate
func pickerView(_: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String! {
return "\(dataSource!.itemsArray[row]) items"
}
func pickerView(_: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
dataSource!.numberOfItems = dataSource!.itemsArray[row]
}
}
DataSource:
class DataSource: NSObject {
let itemsArray = [5, 10, 15]
var pickerIndexPath: NSIndexPath? //allows to hide or show cell with identifier "pickerCell"
dynamic var numberOfItems: Int {
get {
return NSUserDefaults.standardUserDefaults().integerForKey("NumberOfItems")
}
set {
NSUserDefaults.standardUserDefaults().setInteger(newValue, forKey: "NumberOfItems")
NSUserDefaults.standardUserDefaults().synchronize()
}
}
override init() {
super.init()
//Init numberOfItems at first launch
if numberOfItems == 0 {
numberOfItems = 5
}
}
}
I have several questions about this new code. As it is my first attempt with MVC, I wonder if it is a real MVC design pattern code. I also ask myself if it is a complete/correct MVC code: is there anything left to do/modify in order to fully conform to MVC? Furthermore, I've read that passing a model to a view (here, a cell) is not recommended. Thus, what would be the way to make a cell interact with the model without passing the model to it?
