Adding NSMutableAttributedString into a TextField - ios

Question

I have a custom UITextfield which I want when the user finishes typing, a small "R$" must be added at the begging of the text with different size.
I call the method to add the "R$" like this:
self.addTarget(self, action: #selector(setCurrencyLabelPosition), for: .editingDidEnd)
and then I try to change the attributes and content like this:
func setCurrencyLabelPosition(){
let fullText:String = "R$\((self.text)!)"
self.text = fullText
var attribute:NSMutableAttributedString = NSMutableAttributedString(attributedString:self.attributedText!)
attribute.addAttribute(NSFontAttributeName, value:UIFont.systemFont(ofSize: 12), range: NSRange(location: 0, length: 2))
self.attributedText = attribute
}
the original text of this textfield is set for size 40.0, I want only the "R$" to be of size 12.0
The problem I'm facing is that the whole text gets the size 40.0
It prints the "R$" but the size of 40.
Is it possible to do what I'm trying to using NSMutableAttributedString?

Answer 1

I had been working on your question, I think there is a bug in UITextField because if you modify the font to bigger font it works but if you do so but for small font then don't work.
I have done a custom class and added some customizable Inspectable properties, hope this finally help you
This is how looks, Note: the glitch is because of my gif converter
import UIKit
#IBDesignable
class CustomTextField: UITextField {
#IBInspectable var prefix : String = ""
#IBInspectable var removePrefixOnEditing : Bool = true
override init(frame: CGRect) {
super.init(frame: frame)
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
override func awakeFromNib() {
super.awakeFromNib()
self.addTarget(self, action: #selector(setCurrencyLabelPosition), for: .editingDidEnd)
self.addTarget(self, action: #selector(removePrefix), for: .editingDidBegin)
}
func removePrefix(){
if self.attributedText != nil
{
if(self.removePrefixOnEditing)
{
self.defaultTextAttributes = [NSFontAttributeName : UIFont.systemFont(ofSize: 20)]
let prefixRange = NSString(string: (self.attributedText?.string)!).range(of: prefix)
if(prefixRange.location != NSNotFound)
{
self.attributedText = NSAttributedString(string: (self.attributedText?.string.replacingOccurrences(of: prefix, with: ""))!, attributes: self.defaultTextAttributes)
}
}
}
}
func setCurrencyLabelPosition(){
if self.attributedText != nil
{
var fullText:String = "\((self.attributedText?.string)!)"
if(NSString(string: (self.attributedText?.string)!).range(of: prefix).location == NSNotFound)
{
fullText = "\(prefix)\((self.attributedText?.string)!)"
}
//hacky part, seems to be a bug in UITextField
self.defaultTextAttributes = [NSFontAttributeName : UIFont.systemFont(ofSize: 10)]
self.attributedText = NSAttributedString(attributedString: self.changeFontForText(originalText: fullText, text: prefix, basicFont: UIFont.systemFont(ofSize: 20), newFont: UIFont.systemFont(ofSize: 12)))
}
}
func changeFontForText(originalText:String,text:String,basicFont:UIFont, newFont:UIFont) -> NSMutableAttributedString
{
let resultAttributedString = NSMutableAttributedString(string: originalText, attributes: [NSFontAttributeName : basicFont])
let range = NSString(string: originalText).range(of: text)
if(range.location != NSNotFound)
{
resultAttributedString.setAttributes([NSFontAttributeName:newFont], range: range)
}
return resultAttributedString
}
}
Hope this helps