How to change the color of first letter of a textfields text

I have a textfield and starting letter of textfield's text is always a dollar sign.Now i need to change the color of dollar symbol so that dollar symbol and remaining text should be in different color. How can i do this??开发者_开发技巧 Any idea

Can't be done standard. Only one style is allowed in a UITextField.

Best idea: get rid of the $ in the UITextField, replace it with whitespace, then place a UILabel on top.

2nd best idea: subclass UITextField.

Edit:

UITextField has a drawTextInRect: method which is probably all you need to override. Documented here. If you need more help, try googling or searching SO for how to subclass different UI classes, and get a feel for how to override draw methods (e.g. drawRect: for UIView)

Here's the @implementation of my LinethruLabel, a subclass of UILabel. It indicates a "scratched" item with a red linedrawn thru the text. In my case I call [super drawRect:rect]; and UILabel draws the text and background etc., but I'm not sure if whether you'll want to, so take it out if it's not working the way you want. So I guess you'll need to use some of the variations of drawAtPoint:withFont: methods from NSString UIKit category.

@implementation LineThruUILabel

- (void)dealloc {
    [super dealloc];
}


- (id)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        // Initialization code
        drawLine = NO;
    }
    return self;
}


- (void) setDrawLine:(BOOL) newValue
{
    if( drawLine != newValue ){
        drawLine = newValue;        
        [self setNeedsDisplay];
    }
}


- (CGSize) calculateLineWidth
{
    NSString *newText = self.text;
    CGFloat actualFontSize;
    CGFloat width = self.frame.size.width;
    CGSize size =  [newText sizeWithFont: self.font minFontSize:self.minimumFontSize 
                          actualFontSize:&actualFontSize 
                                forWidth:width 
                           lineBreakMode:self.lineBreakMode ];
    return size;    
}

- (void)drawRect:(CGRect)rect {

    [super drawRect:rect];

    CGFloat horizOffset = 0.0;

    if( drawLine ){

        CGSize  lineSize = [self calculateLineWidth];

        CGFloat offset = 1.0;

        // Drawing code
        CGContextRef ctx = UIGraphicsGetCurrentContext();
        //CGFloat w = rect.size.width;
        CGFloat h = rect.size.height;

        // just match the color and size of the horizontal line
        CGContextSetRGBStrokeColor(ctx, 1.0, 0.0, 0.0, 1.0); 
        CGContextSetLineWidth(ctx, 2.0);

        CGContextMoveToPoint(ctx,  horizOffset , h/2 + offset );
        CGContextAddLineToPoint(ctx, lineSize.width + horizOffset + 1.0, h/2 + offset);

        CGContextStrokePath(ctx);
    }   


}