Question

I am making a custom View where I am plotting a curve. Now I want the background of that curve to be like a graph paper.

shall I use a vertical and horizontal lines Or draw a series of rectangles Or use background image?

currently I am using vertical and horizontal lines but the problem is even when I am setting the thickness of the line to be 1 pixel, It still seems to be thicker and If I reduce the thickness to say 0.5 then the color becomes lighter than what I have set it to.

Answer 1

For this kind of thing, if you don’t expect to have to make many, many dynamic changes to the background image, you could just use a carefully-crafted .png. You can even make the thing a single square and then use

view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"template"]];

Although, if you’re doing plot work, then you may want to draw the lines manually as you are. The answer to your question then is to make the stroke width 1.0 but to draw the lines at the halves: so to draw a vertical line down the 100th x pixel column, move the cursor to (99.5, 0.0) and stroke to (99.5, 480.0). CoreGraphics drawing routines draw your stroke centered on the theoretical line you create, and will antialias to physical pixels as necessary.