Creating completely dynamic forms

DynamicFormsTest.swift

/**
 Fixed identifiers for the Fields
 */
enum FieldID{
    case unknown
    case country
    case registration
    case condition
    case quantity
    case year
    case details
    case dateAdded
    case runs
    case image
}


/**
 The cell type used to display the field
 each having their own UITableViewCell subclass
 */
enum FieldCellType{
    case cellDisplayingText
    case cellDisplayingImage
}

/**
 Stores the configuration for a UIDatePicker
 */
struct FieldDateSelectorConfig{
    var minDate: Date
    var maxDate: Date
    var dataType: UIDatePicker.Mode
}

/**
 Describes the type and range of data displayed
 by a field
 */
enum FieldDataType{
    case unknown
    case textEntry
    case textListSelector(list: [String])
    case numberListSelector(list: [Int])
    case numberRangeSelector(start: Int, end: Int, interval: Int?)
    case dateSelector(config: FieldDateSelectorConfig)
    case imageSelector
    
    func cellType() -> FieldCellType{
        switch(self){
        case .imageSelector: return .cellDisplayingImage
        default: return .cellDisplayingText
        }
    }
}

/**
 Stores the ID, Type and current Value for the Field.
 */
class Field{
    var id: FieldID = .unknown
    var dataType: FieldDataType = .unknown
    
    // Two distinct data types for the two types of cells
    // defined at 'FieldCellType'
    
    var displayedValue: String? = nil
    var displayedImage: UIImage? = nil
    
    init() {}
}

/**
 A simple field with a text label
 */

class TextEntryField: Field{
    init(_ id: FieldID, defaultValue: String){
        super.init()
        self.id = id
        self.dataType = .textEntry
        setText(defaultValue)
    }
    
    func setText(_ newValue: String){
        self.displayedValue = newValue
    }
    
    func getText() -> String?{
        return displayedValue
    }
}

/**
 A string list that shows a UIPickerView
 */

class TextListField: Field{
    var defaultValueIndex: Int? = nil
    
    init(_ id: FieldID, values: [String], defaultIndex: Int){
        super.init()
        self.id = id
        self.dataType = .textListSelector(list: values)
        self.displayedValue = values[defaultIndex]
        self.defaultValueIndex = defaultIndex
    }
    
    func getList() -> [String]{
        switch(dataType){
        case .textListSelector(list: let l): return l
        default: return []
        }
    }
    
    func setList(_ list: [String]){
        self.dataType = .textListSelector(list: list)
    }
    
    func setSelectedIndex(_ index: Int){
        let list = getList()
        displayedValue = list[index]
        defaultValueIndex = index
    }
    
    func getSelectedIndex() -> Int{
        return defaultValueIndex ?? 0
    }
}

/**
 A number list that shows a UIPickerView
 */
class NumberListField: Field{
    var defaultValueIndex: Int? = nil
    
    init(_ id: FieldID, values: [Int], defaultIndex: Int){
        super.init()
        self.id = id
        self.dataType = .numberListSelector(list: values)
        self.displayedValue = values[defaultIndex].description
        self.defaultValueIndex = defaultIndex
    }
    
    func getList() -> [Int]{
        switch(dataType){
        case .numberListSelector(list: let l): return l
        default: return []
        }
    }
    
    func setList(_ list: [Int]){
        self.dataType = .numberListSelector(list: list)
    }
    
    func setSelectedIndex(_ index: Int){
        let list = getList()
        displayedValue = list[index].description
        defaultValueIndex = index
    }
    
    func getSelectedIndex() -> Int{
        return defaultValueIndex ?? 0
    }
}

/**
 A field that shows a UIPickerView using two numbers
 */
class NumberRangeField: Field{
    init(_ id: FieldID, start: Int, end: Int, interval: Int?){
        super.init()
        self.id = id
        self.dataType = .numberRangeSelector(start: start, end: end, interval: interval)
        self.displayedValue = ""
    }
}

/**
 A field that shows a UIDatePickerView
 */
class DateField: Field{
    var dateFormat: String{
        return "dd/MM/yyyy"
    }
    
    init(_ id: FieldID, config: FieldDateSelectorConfig, defaultValue: Date){
        super.init()
        self.id = id
        self.dataType = .dateSelector(config: config)
        setDate(defaultValue)
    }
    
    func setDate(_ newDate: Date){
        let df = DateFormatter()
        df.dateFormat = dateFormat
        displayedValue = df.string(from: newDate)
    }
    
    func getDate() -> Date?{
        guard let dv = displayedValue else { return nil }
        
        let df = DateFormatter()
        df.dateFormat = dateFormat
        return df.date(from: dv)
    }
}

/**
 A field that should show the photo gallery
 */
class ImageField: Field{
    
    init(_ id: FieldID, image: UIImage){
        super.init()
        self.id = id
        self.dataType = .imageSelector
        setImage(image)
    }
    
    func setDate(_ image: UIImage){
        displayedImage = image
    }
    
    func getImage() -> UIImage?{
        return di
    }
}

/**
 Describes the order in which the form fields are displayed
 */
class DataSource{
    var fields: [Field] = []
    
    func get(_ id: FieldID) -> Field?{
        return fields.first { return $0.id == id }
    }
    
    func remove(_ id: FieldID){
        fields.removeAll { $0.id == id }
    }
    
    func add(_ field: Field){
        fields.append(field)
    }
}

/*
 =====
 
 Initialization Example
 
 =====
 */

var dataSource = DataSource()

let conditionField = TextListField(.condition, values: ["Good", "Bad"], defaultIndex: 0)
let detailsField = TextEntryField(.details, defaultValue: "Hello")

dataSource.add(conditionField)
dataSource.add(detailsField)

/*
 =====
 
 Data modifying Example
 
 =====
 */

print("== Initial data ==")
print("1.condition = \(conditionField.getList()[conditionField.getSelectedIndex()])")
print("2.details = \(detailsField.getText() ?? "")")

conditionField.setSelectedIndex(1)
detailsField.setText("Hello World")

print("")

print("== Modified data ==")
print("1.condition = \(conditionField.getList()[conditionField.getSelectedIndex()])")
print("2.details = \(detailsField.getText() ?? "")")

/*
=====

UIPickerView-like Example

=====
*/

func showPickerWith(field: Field){
    var options: [String] = []
    
    switch(field.dataType){
    case .numberListSelector(list: let l): options = l.map{ $0.description }
    case .textListSelector(list: let l): options = l
    default: assertionFailure("Incompatible field type")
    }
    
    print("Show UIPickerView with options... \(options)")
}


print("")
print("== UIPickerView example ==")
showPickerWith(field: conditionField)