Ttykuu

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?

Not familiar with Swift at all. but still want to add some comments.

the primary goal of design pattern of "MVC" is to separate the aspects involved, so that extension and modification can be done easily. so yes MVC definitely involves "MODEL" "VIEW" "CONTROLLER". but as you might know it has several mutations: MVVM,MTV(in the case of Django framework). The key is along the directions of separation you made something like that, but I myself don't get bureaucratic about that, as long as I think the refactoring made the whole process much clear, I am okay with my "MVC".

In the case of your refactoring, I am seeing a bit chunk of logic separated into controllers, views, models. which is good enough for me in terms of "MVC".