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Last active February 19, 2019 20:23
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Small abstraction to handle picker view elements with a custom object.
import Foundation
import ObjectiveC
import UIKit
protocol PickerViewItem: Equatable {
typealias TextProperty = KeyPath<Self, String>
typealias SelectProperty = KeyPath<Self, SelectItem>
associatedtype SelectItem
var textProperty: TextProperty { get }
var selectProperty: SelectProperty { get }
}
extension PickerViewItem {
var text: String {
return self[keyPath: textProperty]
}
var selectedItem: SelectItem {
return self[keyPath: selectProperty]
}
}
class PickerView<Element: PickerViewItem>: NSObject, UIPickerViewDataSource, UIPickerViewDelegate {
typealias Search = (Element) -> Bool
typealias ToolBarItemsConfiguration = (title: String, color: UIColor)
typealias SelectedItemEvent = (Element) -> Void
// MARK: Properties
private var elements: [Element]
private var defaultValue: Element?
private weak var textfield: UITextField?
// Index of item selected
private var indexSelected: Int = 0
var itemSelected: Element?
var textSelected: String {
return itemSelected?.text ?? ""
}
var selectedValue: Element.SelectItem? {
return itemSelected?.selectedItem
}
private weak var pickerView: UIPickerView?
// Property holds when a item is selected, also is triggered if a default value was selected
private var selectedItemEvent: SelectedItemEvent?
// Property to hold the search function for the default value
private var search: Search?
// MARK: Functions
init(elements: [Element],
textfield: UITextField,
pickerView: UIPickerView?,
defaultWhere search: Search? = nil) {
self.elements = elements
self.textfield = textfield
self.pickerView = pickerView
self.search = search
super.init()
pickerView?.delegate = self
pickerView?.dataSource = self
self.textfield?.inputView = pickerView
self.configureDefaultValue()
}
private func configureDefaultValue() {
guard let search = self.search else {
return
}
defaultValue = self.elements.first(where: search)
guard let defaultValue = self.defaultValue else {
return
}
self.itemSelected = defaultValue
selectedItemEvent?(defaultValue)
setDefaultValueTextField()
}
private func setDefaultValueTextField() {
guard let defaultValue = self.defaultValue else {
return
}
self.textfield?.text = defaultValue.text
guard let index = elements.firstIndex(where: {$0 == defaultValue}),
let pickerView = self.pickerView else {
return
}
self.pickerView?.selectRow(index, inComponent: 0, animated: true)
self.pickerView?.delegate?.pickerView?(pickerView, didSelectRow: index, inComponent: 0)
}
private func resetAll() {
textfield?.text = nil
itemSelected = nil
}
@objc private func doneButtonPressed() {
textfield?.resignFirstResponder()
guard !elements.isEmpty else {
return
}
let element = elements[indexSelected]
itemSelected = element
textfield?.text = element.text
guard let itemSelected = self.itemSelected else {
return
}
selectedItemEvent?(itemSelected)
}
@objc private func cancelButtonPressed() {
textfield?.resignFirstResponder()
}
func update(elements: [Element], setDefaultValue: Bool = true) {
self.elements = elements
pickerView?.reloadAllComponents()
if setDefaultValue {
self.configureDefaultValue()
}
}
@discardableResult
func addToolBar(tintColor: UIColor,
titleConfiguration: ToolBarItemsConfiguration,
doneButtonTintColor: UIColor,
cancelButton: ToolBarItemsConfiguration,
animated: Bool = false) -> Self {
let toolbar = UIToolbar()
toolbar.barTintColor = tintColor
toolbar.sizeToFit()
let cancelBarButton = UIBarButtonItem(title: cancelButton.title,
style: .plain,
target: self,
action: #selector(cancelButtonPressed))
cancelBarButton.tintColor = cancelButton.color
let titleBarButton = UIBarButtonItem(title: titleConfiguration.title, style: .plain, target: nil, action: nil)
titleBarButton.tintColor = titleConfiguration.color
let doneBarButton = UIBarButtonItem(barButtonSystemItem: .done, target: self, action: #selector(doneButtonPressed))
doneBarButton.tintColor = doneButtonTintColor
let buttons = [cancelBarButton,
// This item add more space between buttons
UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil),
titleBarButton,
// This item add more space between buttons
UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil),
doneBarButton]
toolbar.setItems(buttons, animated: animated)
textfield?.inputAccessoryView = toolbar
return self
}
@discardableResult
func selectedItem(_ selectedItemEvent: @escaping SelectedItemEvent) -> Self {
self.selectedItemEvent = selectedItemEvent
return self
}
// MARK: DataSource/Delegate
func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 1
}
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return elements.count
}
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
indexSelected = row
}
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
let element = elements[row]
return element.text
}
}
var associatedObjectHandle: UInt8 = 0
extension UITextField {
func pickerView<T: PickerViewItem>(itemType type: T.Type = T.self) -> PickerView<T>? {
return objc_getAssociatedObject(self, &associatedObjectHandle) as? PickerView<T>
}
func addPickerView<T: PickerViewItem>(_ pickerView: UIPickerView = .init(),
elements: [T],
defaultWhere predicate: PickerView<T>.Search? = nil) -> PickerView<T>? {
// Prevent reset a pre set element
if objc_getAssociatedObject(self, &associatedObjectHandle) == nil {
let pickerView = PickerView(elements: elements, textfield: self, pickerView: pickerView, defaultWhere: predicate)
objc_setAssociatedObject(self, &associatedObjectHandle, pickerView, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
return pickerView
} else {
return self.pickerView(itemType: T.self)
}
}
}
// USAGE
struct Document: PickerViewItem {
let name: String
let code: String
var selectProperty: KeyPath<Document, String> {
return \.code
}
var textProperty: KeyPath<Document, String> {
return \.name
}
}
let textfield = UITextField()
// creating picker
textfield.addPickerView(elements: [ Document(name: "License", code: "D"),
Document(name: "Id Number", code: "I"),
Document(name: "Passport", code: "P")])?
// adding toolbar if you needed
.addToolBar(tintColor: .black, titleConfiguration: (title: "Title", color: .red), doneButtonTintColor: .red, cancelButton: (title: "Cancel", color: .red))
// get object when a item is selected
.selectedItem { document in
print("document \(document)")
}
// updating elements
textfield.pickerView(itemType: Document.self)?.update(elements: [Document(name: "Passport", code: "P")])
// getting elements
let selectedValue = textfield.pickerView(itemType: Document.self)?.selectedValue
let textSelected = textfield.pickerView(itemType: Document.self)?.textSelected
let itemSelected = textfield.pickerView(itemType: Document.self)?.itemSelected
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