In UITextfield, When applying color using NSMutableAttributedString the color is not applied correctly when unfocusing - xamarin

Question

Using NSMutableAttributedString, I applied color for a specific character in a string using UITextfield. My Code:
uITextField = new UITextField(); uITextField.BackgroundColor = UIColor.LightGray;
uITextField.Frame = new CGRect(10, 150, 350, 40);
uITextField.Text = "Hai i am ________________";
uITextField.TextColor = UIColor.Green;
uITextField.EditingChanged += UITextField_EditingChanged;
private void UITextField_EditingChanged(object sender, EventArgs e)
{
var promptStringAttributes = new UIStringAttributes
{
ForegroundColor = UIColor.Red
};
var promptString = new NSMutableAttributedString(uITextField.Text);
char[] mText = uITextField.Text.ToCharArray();
Char prchar = '_';
for (int i = 0; i < mText.Length; i++)
{
if (!string.IsNullOrEmpty(uITextField.Text) && prchar == mText[i])
{
promptString.SetAttributes(promptStringAttributes.Dictionary, new NSRange(i, 1));
}
}
uITextField.AttributedText = promptString;
}
Initially, the text will be in Green color. See the below image:
After deleting the last character in the UItextfield, I will change the color of some character to red
The problem which I am facing is after unfocusing the UITextfield, the Red color is applied to all the character in the UITextField and the text color is not displayed correctly. Only the set attribute color is applied for all the character in the string. See the below image:
Please give a possible solution to restrict of applying the set attribute color for all the string when unfocusing the UITextField in xamarin iOS.

Answer 1

Improve your method
var promptStringAttributes_Red = new UIStringAttributes
{
ForegroundColor = UIColor.Red
};
var promptStringAttributes_Green = new UIStringAttributes
{
ForegroundColor = UIColor.Green
};
var promptString = new NSMutableAttributedString(uITextField.Text);
char[] mText = uITextField.Text.ToCharArray();
Char prchar = '_';
for (int i = 0; i < mText.Length; i++)
{
if (!string.IsNullOrEmpty(uITextField.Text) && mText[i] ==prchar)
{
promptString.SetAttributes(promptStringAttributes_Red.Dictionary, new NSRange(i, 1));
}
else
{
promptString.SetAttributes(promptStringAttributes_Green.Dictionary, new NSRange(i, 1));
}
}
uITextField.AttributedText = promptString;