9 Notes In February 2020

1. Hide Element on Select tableView cell

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {

    if indexPath.row == currentRow {
        if cellTapped == false {
            cell.image.hidden = false
        } else {
            cell.image.hidden = true
        }
    }

    return cell
}

func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
    //CODE TO BE RUN ON CELL TOUCH

    let selectedRowIndex = indexPath
    currentRow = selectedRowIndex.row
    tableView.reloadData()

}

source: https://stackoverflow.com/a/34603224/8366535

2. SwiftUI Basic Note

- Parent view just have 10 limits to make child views
example:

Text("Hello World") // 0
.
.
.

Text("Hello World") // 9

- Alternative use form and section split that views. If using multiple forms it doesn't work.
example:

Form {
    Section {
        Text("SwiftUI")
        Text("SwiftUI")
        Text("SwiftUI")
    }

   Section {
        Text("SwiftUI")
        Text("SwiftUI")
        Text("SwiftUI")
    }
}

-  NavigationView  : to add  navigation on the top controller
-  .navigationBarTitle(Text("SwiftUI APP"))  : for title navigation in swiftUI, displayMode
- displayMode: .large  : for change title size (default is .large), .large is big use big font and .inline is normal font
- .colorScheme(.dark)  : change theme .dark or .light mode theme
-  .foregroundColor(.blue) :  for text color in form

import SwiftUI

struct BasicContentView: View {
    var body: some View {
        NavigationView {
            Form {
                Section {
                    Text("SwiftUI")
                    Text("SwiftUI")
                    Text("SwiftUI")
                    Text("SwiftUI")
                }
                Section {
                    Text("Hi")
                    Text("My Name Is LF")
                    Text("I Know ")
                    Text("About SwiftUI")
                    Text("About SwiftUI")
                }
            }
            .navigationBarTitle(Text("SwiftUI APP"), displayMode: .large)
            .colorScheme(.dark) // For CHANGE DARK MODE / LIGHT MODE
            .foregroundColor(.blue)
        }
    }
}

- Create a new variable must be  use @State(property wrapper), if you did not use a that must be an error like this below
  Left side of mutating operator isn't mutable: 'self' is immutable
- In SwiftUI Segmented Control create with picker 

- Color is a View (Color.red), example :

.background(Color.red)

-  every time you write some View. This means “one specific type that conforms to the View protocol(source: https://www.hackingwithswift.com/books/ios-swiftui/why-does-swiftui-use-some-view-for-its-view-type)


3. Custom leftBarButton can still swipe left

Use extension UINavigationController

extension UINavigationController {
    open override func viewDidLoad() {
        super.viewDidLoad()
        interactivePopGestureRecognizer?.delegate = self as? UIGestureRecognizerDelegate
    }
}

Full code here:

import UIKit

class NavigateToAppsViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.backgroundColor = .blue
        let backButton = UIButton(type: .system)
        backButton.setImage(UIImage(named: "ic_Mystery"), for: .normal)
        backButton.frame.size = CGSize(width: 28, height: 34)
        backButton.addTarget(self, action: #selector(dismissSelf), for: .touchUpInside)
        navigationItem.leftBarButtonItems = [UIBarButtonItem(customView: backButton)]
    }
    
    @IBAction @objc func dismissSelf() {
        UIView.animate(withDuration: 0.3) {
            print("dismiss")
            self.navigationController?.popViewController(animated: true)
        }
    }
}

extension UINavigationController {
    open override func viewDidLoad() {
        super.viewDidLoad()
        interactivePopGestureRecognizer?.delegate = self as? UIGestureRecognizerDelegate
    }
}

4. Dismiss Keyboard and open picker/popup use text field

- This example to use two text field and one of the other for picker or popup, if this code
https://medium.com/@KaushElsewhere/how-to-dismiss-keyboard-in-a-view-controller-of-ios-3b1bfe973ad1
doesn't work

class ViewConrtoller: UIViewController {

    @IBOutlet weak var textFieldOne: UITextField!
    @IBOutlet weak var textFieldTwo: UITextField!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
    }
    
    //MARK: use editing did begin

    @IBAction func handleTextFieldAsButton(_ sender: UITextField) {

        DispatchQueue.main.asyncAfter(deadline: .now() + 0.3) {

            self.textField2.resignFirstResponder()
            print("open popup")

        }

    }
    
}

5. Integer rounding off (down) swift

- user this logic

   // MARK: Digits add

    func handleDigits(_ first: Int, _ count: Int) -> Int {
        var digits: [Int] = []
        digits.append(first)
        for _ in 1 ..< count {
            digits.append(0)
        }
        let intValue = digits.reduce(0) { $0 * 10 + $1 }

        return intValue
    }

- how to use

let numbers = "1234"

guard let _amount = numbers?.first else {
     return false
}


let digitsAdd = handleDigits(Int("\(_amount)") ?? 0, numbers?.count ?? 0)

print(numbers, "-->", digitsAdd) // 1234 --> 1000

or you can use this metthod

let digitsAdd = handleDigits(Int("\(_amount)") ?? 0, numbers?.count ?? 0)

print(numbers, "-->", digitsAdd) // 1234 --> 1000

https://stackoverflow.com/a/40951297/8366535

6. ScrollView can't scroll
ScrollView in swift 5.1 can't scroll, try this soluttion

- unchecklist content layoutt guides

 


7. Why UILabel get error "label Thread 1: Fatal error: Unexpectedly found nil while implicitly unwrapping an Optional value"

In condition to solve a problem is It is very common to define outlets as:

@IBOutlet weak var label: UILabel!

...instead of the safer:

@IBOutlet weak var label: UILabel?

https://stackoverflow.com/a/43404173/8366535

https://stackoverflow.com/questions/43404111/why-does-uilabel-text-result-in-fatal-error-unexpectedly-found-nil-while-unwra


8. Get row height size UITableViewCell 

How  to get the row height for each row in an UITableView in swift

var height: CGFloat = 0
for cell in tableView.visibleCells {
    height += cell.bounds.height // all row cell
    // or
    height = cell.bounds.height // for 1 row cell

}

print(height)

link: https://stackoverflow.com/a/48107136/8366535

// simple code use this

let height = tableView.contentSize.height

tableHeight.constant = height

9. Tuples with Array

Here example use tuple with an array:

import UIKit


class ViewController: UIViewController {
    
    
    var tuples = [(key: String, value: String)]()

    override func viewDidLoad() {
        super.viewDidLoad()
        let some = "email=me@gmaa.com&int=20&Id=hqr123id"

        let array = some.components(separatedBy: "&")
        for i in array {
            let arr = i.components(separatedBy: "=")
            tuples.append((arr[0], arr[1]))
            print(i.components(separatedBy: "="))
        }

        print("\n", tuples)        
        
    }
    
}