Drawing ruled lines on a UITextView for IPhone

Question

I would like to create a view like the notes app on iPhone and therefor need the view to have ruled lines as per the notes app, I have done this in windows where you need to get the font metrics and then draw the lines onto the device context, has anyone done this in the UITextView if so some help would be appriciated

Answer 1

You can try setting the backgroundColor of you textView using an image with ruled lines

textView.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"RuledLinesPage.png"]];

Color with pattern image creates a tiled image if the area to be filled with the color is larger than the image. So you will have to make sure that the image size is correct size/tileable (I don't think 'tileable' is a real word but i hope you get what i mean). Also you will have to create the image with ruled lines to best match you textView's font.

Good Luck.

Answer 2

@lukya, Your solution is bit messy as when we scroll the UITextView the text only scrolls leaving the lines (coming from the image) in its place.

Answer 3

I think this works OK but I feel it has been hacked and I do not fully undestand the mechanism of the UITextView class;

first you must add the following to your delegate to force a redraw on scrolling

• (void)scrollViewDidScroll:(UIScrollView *)scrollView {
  // NSLog(@"scrollViewDidScroll The scroll offset is ---%f",scrollView.contentOffset.y); [noteText setNeedsDisplay]; }

then implement drawRect in the subclass as so

• (void)drawRect:(CGRect)rect { // Drawing code // Get the graphics context CGContextRef ctx = UIGraphicsGetCurrentContext();

  [super drawRect:rect];

  // Get the height of a single text line NSString *alpha = @"ABCD"; CGSize textSize = [alpha sizeWithFont:self.font constrainedToSize:self.contentSize lineBreakMode:UILineBreakModeWordWrap]; NSUInteger height = textSize.height;

  // Get the height of the view or contents of the view whichever is bigger textSize = [self.text sizeWithFont:self.font constrainedToSize:self.contentSize lineBreakMode:UILineBreakModeWordWrap]; NSUInteger contentHeight = (rect.size.height > textSize.height) ? (NSUInteger)rect.size.height : textSize.height;

  NSUInteger offset = 6 + height; // MAGIC Number 6 to offset from 0 to get first line OK ??? contentHeight += offset; // Draw ruled lines CGContextSetRGBStrokeColor(ctx, .8, .8, .8, 1); for(int i=offset;i < contentHeight;i+=height) { CGPoint lpoints[2] = { CGPointMake(0, i), CGPointMake(rect.size.width, i) }; CGContextStrokeLineSegments(ctx, lpoints, 2); } }

Still worry about this Magic Number 6

Bob