I am using a framework to provide custom UI elements in my main project. There are class properties for the UI element classes within the framework. Each of these classes extend common iOS classes, and have their own .xib files.
For instance:
open class BaseTableViewCell : UITableViewCell {
#IBOutlet public var title: UILabel!
open func setContentDimmed(_ dimmed:Bool) {
if dimmed {
self.title.alpha = 0.3 // < crashes with nil object
} else {
self.title.alpha = 1.0 // < crashes with nil object
}
}
The problem is that when I instantiate a BaseTableViewCell object and call the setContentDimmed(true) func, it crashes. The only way I can make it work is if I change
#IBOutlet public var title: UILabel!
to an optional like:
#IBOutlet public var title: UILabel?
then I MUST unwrap it or its nil (even though its NOT declared as un unwrapped optional in the framework)
open class BaseTableViewCell : UITableViewCell {
#IBOutlet public var title: UILabel?
open func setContentDimmed(_ dimmed:Bool) {
if let titleLabel = self.title {
if dimmed {
titleLabel.alpha = 0.3 // < doesn't crash, works
} else {
titleLabel.alpha = 1.0 // < doesn't crash, works
}
}
}
This was working before moving BaseTableViewCell into my framework. Now its always an optional that MUST be unwrapped or it's nil. Any idea whats going on here?
I've tried everything - Im out of ideas.
Why not do something like this?
#IBOutlet public var title: UILabel!{
didSet{
guard dimmed != nil { title.alpha = 1.0; return }
title.alpha = dimmed! ? 0.3 : 1.0
}
}
var dimmed: Bool? {
didSet{
guard title != nil else { return }
title.alpha = dimmed! ? 0.3 : 1.0
}
}
You are most likely just calling the setContentDimmed before the property is even set.
Related
I'm very new to ReactiveSwift and MVVM as a whole. I'm trying to validate phone numbers entered into a textfield and enable/disable a button depending on the validation result.
In the app, there is a textfield and a UIButton button called Submit. For phone number validating, I'm using an open source library called [PhoneNumberKit][1]. It also provides a UITextField subclass which formats the user input.
I mashed together a solution that looks like this.
class ViewController: UIViewController {
#IBOutlet weak var textField: PhoneNumberTextField!
#IBOutlet weak var submitButton: UIButton!
override func viewDidLoad() {
super.viewDidLoad()
textField.becomeFirstResponder()
submitButton.isEnabled = false
let textValuesSignal = textField.reactive.continuousTextValues
SignalProducer(textValuesSignal).start { result in
switch result {
case .value(let value):
print(value)
self.submitButton.isEnabled = self.isPhoneNumberValid(value)
case .failed(let error):
print(error)
self.submitButton.isEnabled = false
case .interrupted:
print("inturrupted")
self.submitButton.isEnabled = false
case .completed:
print("completed")
}
}
}
func isPhoneNumberValid(_ phoneNumberString: String) -> Bool {
do {
let phoneNumber = try PhoneNumberKit().parse(phoneNumberString)
let formattedPhoneNumber = PhoneNumberKit().format(phoneNumber, toType: .e164)
print("Phone number is valid: \(formattedPhoneNumber)")
return true
} catch let error {
print("Invalid phone number: \(error)")
return false
}
}
}
This does the job but not very elegantly. Also there is a significant lag between user input and the UI changing.
Another thing is my above solution doesn't conform to MVVM. I gave it another go.
class ViewController: UIViewController {
#IBOutlet weak var textField: PhoneNumberTextField!
#IBOutlet weak var submitButton: UIButton!
private let viewModel = ViewModel()
override func viewDidLoad() {
super.viewDidLoad()
textField.becomeFirstResponder()
submitButton.reactive.isEnabled <~ viewModel.isPhoneNumberValid
viewModel.phoneNumber <~ textField.reactive.continuousTextValues
}
}
class ViewModel {
let phoneNumber = MutableProperty("")
let isPhoneNumberValid = MutableProperty(false)
init() {
isPhoneNumberValid = phoneNumber.producer.map { self.validatePhoneNumber($0) } // Cannot assign value of type 'SignalProducer<Bool, NoError>' to type 'MutableProperty<Bool>'
}
private func validatePhoneNumber(_ phoneNumberString: String) -> Bool {
do {
let phoneNumber = try PhoneNumberKit().parse(phoneNumberString)
let formattedPhoneNumber = PhoneNumberKit().format(phoneNumber, toType: .e164)
print("Phone number is valid: \(formattedPhoneNumber)")
return true
} catch let error {
print("Invalid phone number: \(error)")
return false
}
}
}
I'm getting the below error in the initializer when I'm assigning the result from the validatePhoneNumber function's to the isPhoneNumberValid property.
Cannot assign value of type 'SignalProducer' to type 'MutableProperty'
I can't figure out how to hook up the phone number validation part with the submit button's isEnabled property and the tap action properly.
Demo project
Try setting the property in init and mapping the property itself rather than a producer:
let isPhoneNumberValid: Property<Bool>
init() {
isPhoneNumberValid = phoneNumber.map { ViewModel.validatePhoneNumber($0) }
}
You’ll have to make validatePhoneNumber a static method because self won’t be available yet.
This is a more typical reactive way of doing this because you define one property completely in terms of another one during the view model’s initialization.
I'm trying to pass data between viewControllers, but something seems wrong.
The first viewController I want to set the "Bool" to the protocol function to be able to recover in the other screen. What am I doing wrong, I always used protocols but at this time I got in trouble.
That's how I'm doing that:
//
// ComboBoxNode.swift
//
import Foundation
import SWXMLHash
protocol ComboBoxNodeDelegate {
func getCustomOption(data:Bool)
}
class ComboBoxNode: FormControlNode, IFormControlDataSource {
var listType: String?
var dataSource: String?
var dataSourceValue: String?
var dataSourceText: String?
var hasCustomOption:Bool?
var customOptionText: String?
var ctrlDataSourceType: String?
var parameters = [ParameterNode]()
var staticList: FormControlStaticListNode?
var delegate:ComboBoxNodeDelegate?
override init(indexer: XMLIndexer) {
super.init(indexer: indexer)
guard let element = indexer.element else {
preconditionFailure("Error")
}
let isCustomOption = element.bool(by: .hasCustomOption) ?? hasCustomOption
if isCustomOption == true {
self.delegate?.getCustomOption(data: hasCustomOption!)
}
self.readFormControlDataSource(indexer: indexer)
}
override func accept<T, E: IViewVisitor>(visitor: E) -> T where E.T == T {
return visitor.visit(node: self)
}
}
That's how I'm trying to recover on next screen:
// FormPickerViewDelegate.swift
import Foundation
import ViewLib
import RxSwift
class FormPickerViewDelegate: NSObject {
var items = Variable([(value: AnyHashable, text: String)]()) {
didSet {
PickerNodeDelegate = self
self.setDefaultValues()
}
}
private var controlViewModel: FormControlViewModel
private var customText:Bool?
private var PickerNodeDelegate:ComboBoxNodeDelegate?
init(controlViewModel: FormControlViewModel) {
self.controlViewModel = controlViewModel
}
func getItemByValue(_ value: Any) -> (AnyHashable, String)? {
if value is AnyHashable {
let found = items.value.filter {$0.value == value as! AnyHashable}
if found.count >= 1 {
return found[0]
}
}
return nil
}
}
extension FormPickerViewDelegate:ComboBoxNodeDelegate {
func getCustomOption(data: Bool) {
customText = data
}
}
Instead of setting PickerNodeDelegate = self in didSet {} closure
var items = Variable([(value: AnyHashable, text: String)]()) {
didSet {
PickerNodeDelegate = self
self.setDefaultValues()
}
}
Assign it in your init() function instead
init(controlViewModel: FormControlViewModel) {
self.controlViewModel = controlViewModel
PickerNodeDelegate = self
}
Note, your should declare your delegate to be weak also, since it's a delegate, your protocol should conform to be a class type in order to be weakified.
protocol ComboBoxNodeDelegate: class
...
weak var delegate: ComboBoxNodeDelegate?
Here is an example, hope it helps!
protocol ComboBoxNodeDelegate {
func getCustomOption(data:Bool) -> String
}
class ViewOne:ComboBoxNodeDelegate {
var foo:Bool = false
var bar:String = "it works!"
/** Return: String */
func getCustomOption(data:Bool) -> String { //conform here to protocol
// do whatever you wanna do here ...example
self.foo = data // you can set
return bar // even return what you want
}
//initialize
func initalizeViewTwo() {
let v2 = ViewTwo()
v2.delegate = self //since `self` conforms to the ComboBoxNodeDelegate protcol you are allowed to set
}
}
class ViewTwo {
var delegate:ComboBoxNodeDelegate?
func getCustomOption_forV1() {
let view2_foo = delegate.getCustomOption(data:true)
print(view2_foo) // should print "it works!"
}
}
All parameters passed around in Swift are constants -- so you cannot change them.
If you want to change them in a function, you must declare your protocol to pass by reference with inout:
protocol ComboBoxNodeDelegate {
func getCustomOption(data: inout Bool)
}
Note: you cannot pass a constant (let) to this function. It must be a variable -- which I see you are doing!
I have viewModel:
class EditFoodViewViewModel {
private var food: Food
var foodImage = Variable<NSData>(NSData())
init(food: Food) {
self.food = food
self.foodImage.value = food.image!
}
}
And ViewController:
class EditFoodViewController: UIViewController {
public var food: EditFoodViewViewModelType?
#IBOutlet weak var foodThumbnailImageView: UIImageView!
override func viewDidLoad() {
super.viewDidLoad()
guard let foodViewModel = food else { return }
foodViewModel.foodImage.asObservable().bind(to: foodThumbnailImageView.rx.image).disposed(by: disposeBag)
}
}
In the last line of viewController (where my UIImageView) a get error:
Generic parameter 'Self' could not be inferred
How to solve my problem? How to set image to imageView with rxSwift?
Almost invariably, when you see the error: "Generic parameter 'Self' could not be inferred", it means that the types are wrong. In this case you are trying to bind an Observable<NSData> to an Observable<Image?>.
There's a few other issues with your code as well.
it is very rare that a Subject type should be defined with the var keyword and this is not one of those rare times. Your foodImage should be a let not a var.
Variable has been deprecated; don't use it. In this case, you don't even need a subject at all.
NSData is also inappropriate in modern Swift. Use Data instead.
Based on what you have shown here, I would expect your code to look more like this:
class EditFoodViewViewModel: EditFoodViewViewModelType {
let foodImage: Observable<UIImage?>
init(food: Food) {
self.foodImage = Observable.just(UIImage(data: food.image))
}
}
class EditFoodViewController: UIViewController {
#IBOutlet weak var foodThumbnailImageView: UIImageView!
public var food: EditFoodViewViewModelType?
private let disposeBag = DisposeBag()
override func viewDidLoad() {
super.viewDidLoad()
guard let foodViewModel = food else { return }
foodViewModel.foodImage
.bind(to: foodThumbnailImageView.rx.image)
.disposed(by: disposeBag)
}
}
In my view controller:
class FoodAddViewController: UIViewController, UIPickerViewDataSource, UITextFieldDelegate, UIPickerViewDelegate {
let TAG = "FoodAddViewController"
// Retreive the managedObjectContext from AppDelegate
let managedObjectContext = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext
#IBOutlet weak var foodName: UITextField!
#IBOutlet weak var foodPortion: UITextField!
#IBOutlet weak var foodCalories: UITextField!
#IBOutlet weak var foodUnit: UILabel!
#IBOutlet weak var unitPicker: UIPickerView!
#IBOutlet weak var unitPickerViewContainer: UIVisualEffectView!
/*
unrelated code has been ommited
*/
func validateAllTextFields(textFields: [UITextField] = [foodName as UITextField, foodPortion, foodCalories]) -> Bool {
var result = true
for textField in textFields {
result = validateTextField(textField) && result
}
return result
}
func validateTextField(textField: UITextField) -> Bool{
let correctColor = UIColor.redColor().CGColor, normalColor = UIColor.blackColor().CGColor
var correct = true
if textField == foodPortion || textField == foodCalories{
if !Misc.isInteger(textField.text!){
correct = false
}
}
if textField.text!.isEmpty {
correct = false
}
textField.layer.borderColor = correct ? normalColor : correctColor
return correct
}
}
I have a few textfields, and in my validateTextField can verify one at a time, and I want my validateAllTextFields be able to verify a give list of textfield by checking them one by one, if the list is not given, I want to check a given default list that contains all three textfield.
The code I imagine to be something like:
func validateAllTextFields(textFields: [UITextField] = [foodName as UITextField, foodPortion, foodCalories]) -> Bool {
var result = true
for textField in textFields {
result = validateTextField(textField) && result
}
return result
}
However Xcode gives an error back:
instance member cannot be used on type viewcontroller
What's the cause and how to fix?
You cannot use instance variables in function declarations. Call the function with your textFields array and pass the parameters.
func validateAllTextFields(textFields: [UITextField] ) -> Bool {
var result = true
for textField in textFields {
result = validateTextField(textField) && result
}
return result
}
somehwere in your class:
validateAllTextFields(textFields: [foodName, foodPortion, foodCalories])
Or you check inside of your function if textFields is empty and than u use the instance variables
func validateAllTextFields(textFields: [UITextField] ) -> Bool {
if textFields.count == 0 {
textFields = [foodName, foodPortion, foodCalories]
}
var result = true
for textField in textFields {
result = validateTextField(textField) && result
}
return result
}
Let's say I have a weak var view: UIView? in my class Button {}. Is there any way to know when view loses its reference and becomes nil?
I tried using weak var view: UIView? {} (aka a computed property) in order to override set {}, but that didn't work because now it's a computed property and can't store a weak reference (how annoying!).
Edit:
#fqdn's answer didn't work with this code... Try it in an Xcode Playground
import UIKit
class Test {
weak var target: UIView? {
willSet {
if !newValue { println("target set to nil") }
else { println("target set to view") }
}
}
}
class Button {
var view: UIView? = UIView()
}
var t = Test()
var b = Button()
t.target = b.view
b.view = nil // t.target's willSet should be fired here
Your output console should display:
target set to view
target set to nil
My console displays
target set to view
b.view is the strong reference for the UIView instance. t.target is the weak reference. Therefore, if b.view is set to nil, the UIView instance is deallocated and t.target will be equal to nil.
If your button is holding a reference to another view, it should either be an owner of that view (i.e., it should hold a strong reference) or it should not care when that view goes away (i.e., its weak reference to it becomes nil.) There is no notification when weak references become nil, and that is by design.
In particular, Swift property observers are not called when weak references become nil, as the following code demonstrates:
class A : CustomStringConvertible {
var s: String?
init(s: String) {
self.s = s;
print("\(self) init")
}
deinit {
print("\(self) deinit")
}
var description: String {
get { return "[A s:\(s ?? "nil")]" }
}
}
class B : CustomStringConvertible {
weak var a:A? {
willSet {
print("\(self) willSet a")
}
didSet {
print("\(self) didSet a")
}
}
init(a: A?) {
self.a = a
print("\(self) init")
}
deinit {
print("\(self) deinit")
}
var description: String {
get { return "[B a:\(a == nil ? "nil" : String(describing: a!))]" }
}
}
func work() {
var a: A? = A(s: "Hello")
var b = B(a: a)
print("\(b)")
a = nil
print("\(b)")
b.a = A(s: "Goodbye")
}
work()
When work() is called, the console gives the following output:
[A s:Hello] init
[B a:[A s:Hello]] init
[B a:[A s:Hello]]
[A s:Hello] deinit
[B a:nil]
[A s:Goodbye] init
[B a:nil] willSet a
[B a:[A s:Goodbye]] didSet a
[A s:Goodbye] deinit
[B a:nil] deinit
Notice that in neither case of the instance of A deallocating and its weak reference in the instance of B becoming nil are the property observers called. Only in the direct case of assignment to B.a are they called.