Swift 4: How to change font attributes of number in multiple UITextFields when .count > 3 and how to reverse calculation? - uitextfield

Question

I have three UITextFields that will only contain a whole number between 0 and either 13066 or 3915 maximum. It's presented with a special font where font1 at 50pt is larger than font2 at 50pt so I only need to play around with the font file, not the size.
1) I need help finding a way to have the hundreds presented with font2 but when the number >= 1000, the digits for thousands is presented with font1, while the hundreds still maintain font2. As this is a UITextField input, I need this to happen real-time.
Animated picture of how the end result eventually will be!
2) If you watch the animation, you'll see that each of the three fields totals to the field at the bottom. This is straight forward. However, I also want to reverse this, i.e filling in the total and the dials and digits should fill in as shown (half in each MAIN up to 3920 and remaining in CTR up to 13066). How do I code a functioning reversible calculation like that and avoid conflict?
This is what I got so far but it doesn't quite do what I want yet:
`class ViewController: UIViewController, UITextFieldDelegate {
#IBOutlet weak var centerField: UITextField!
#IBOutlet weak var main1Field: UITextField!
#IBOutlet weak var main2Field: UITextField!
#IBOutlet weak var totalField: UITextField!
override func viewDidLoad() {
super.viewDidLoad()
//UITextField delegation
centerField.delegate = self
main1Field.delegate = self
main2Field.delegate = self
totalField.delegate = self
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
//Change font when number input exceeds 3 digits
func getAttributedString(for number: Int) -> NSAttributedString {
let defaultAttributes = [
NSAttributedStringKey.font: UIFont(name: "PMDG_777_DU_A", size: UIFont.labelFontSize)!
]
let bigNumberAttributes = [
NSAttributedStringKey.font: UIFont(name: "PMDG_777_DU_B", size: UIFont.labelFontSize)!
]
let attributedString = NSMutableAttributedString(string: "\(number)", attributes: defaultAttributes)
if attributedString.length > 3 {
let substr = attributedString.string.dropLast(3)
let range = NSMakeRange(0, substr.utf16.count)
attributedString.setAttributes(bigNumberAttributes, range: range)
}
return attributedString
}
//Hide keyboard when hitting Return
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
textField.resignFirstResponder()
return true
}
//Hide keyboard when tapping outside of field
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
self.view.endEditing(true)
}
//Real-time calculation of entries made to the fields and output it live to the total
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
//Convert the String inserted into the fields into Int and create variables
let centerFuel = Int(centerField.text!) ?? 0
centerField.attributedText = getAttributedString(for: centerFuel)
let main1Fuel = Int(main1Field.text!) ?? 0
main1Field.attributedText = getAttributedString(for: main1Fuel)
let main2Fuel = Int(main2Field.text!) ?? 0
main2Field.attributedText = getAttributedString(for: main2Fuel)
let total: Int = centerFuel + main1Fuel + main2Fuel
totalField.attributedText = getAttributedString(for: total)
return true
}

Answer 1

Use NSMutableAttributedString:
func getAttributedString(for number: Int) -> NSAttributedString {
precondition(number >= 0)
let defaultAttributes = [
NSAttributedStringKey.font: UIFont.systemFont(ofSize: 18)
]
let bigNumberAttributes = [
NSAttributedStringKey.font: UIFont.systemFont(ofSize: 30)
]
let attributedString = NSMutableAttributedString(string: "\(number)", attributes: defaultAttributes)
if attributedString.length > 3 {
let range = NSMakeRange(0, attributedString.length - 3)
attributedString.setAttributes(bigNumberAttributes, range: range)
}
return attributedString
}
Then set the attributedText property on your label:
label.attributedText = getAttributedString(for: 13006)
And you can get result like this:
Adjust the styles to taste!

Answer 2

Here is a sample solution:
func attributedString(fromIntStr: String) -> NSAttributedString {
print("Working with: \(fromIntStr)")
let finalAttr = NSMutableAttributedString.init()
let length = fromIntStr.count
if length > 3 //we test this because we can't do dropLast(n) where n is negative
{
let start = String(fromIntStr.dropLast(3))
let firstPart = NSAttributedString.init(string: start,
attributes: [.font: UIFont.systemFont(ofSize: 20)])
finalAttr.append(firstPart)
}
var dropEnd = 0
if length > 3 //we test this because we can't do dropFirst(n) where n is negative
{
dropEnd = length - 3
}
else
{
dropEnd = 0 //That's just an explicit value but it was already set by default
}
let end = String(fromIntStr.dropFirst(dropEnd))
let lastPart = NSAttributedString.init(string: end,
attributes: [.font: UIFont.systemFont(ofSize: 15)])
finalAttr.append(lastPart)
//It seems that you want a right alignement and since we are using NSAttributedString we can do it by using ParagraphStyle
let paragraphStyle = NSMutableParagraphStyle.init()
paragraphStyle.alignment = .right
finalAttr.addAttribute(.paragraphStyle,
value: paragraphStyle,
range: NSRange(location: 0, length: finalAttr.length))
return finalAttr
}
It can be tested on Playground adding this at the end:
let values = ["", "9", "89", "789", "6789", "56789"]
let view = UIView.init(frame: CGRect(x: 0, y: 0, width: 800, height: 400))
for (i, str) in values.enumerated().reversed()
{
let label = UILabel.init(frame: CGRect(x: 0, y: i*50, width: 800, height: 50))
let attr = attributedString(fromIntStr: str)
label.attributedText = attr
view.addSubview(label)
}
view
There are various way to do this but here is the logic I used:
• Create a NSMutableAttributedString.
• Separate the string in two strings (one for 0-999, the other one for the rest)
• Create from them two NSAttributedString with the corresponding font
• Append them to the NSMutableAttributedString previously created.
Of course this could be improved:
Is dropFirst()/dropLast() the best solutions?
I supposed that you add already a String value from a Int (I didn't do the conversion).
Another solution more classic would have been:
• Create a NSMutableAttributedString from the whole String.
• Apply small font on range last from last-3
• Apply big font on range start to last -3
Last point be ommited if you apply the big font from the start on the whole string.