Question

I am trying to write a program that graphs parabolas on the screen on my iPhone using iOS and objective C.

Towards this end, I must be able to toggle whether individual pixels on the screen of the iPhone are black or white.

How can I control individual pixels? I couldn’t find an appropriate UIView object to use.

Answer 1

You might want to read the code for Core Plot (or just use it)

http://code.google.com/p/core-plot/

Basically, it uses the Core Graphics library. Here’s the code to draw a bar graph

http://code.google.com/searchframe#yOGuvxPxbkc/framework/Source/CPBarPlot.m&l=330

which calls this

http://code.google.com/searchframe#yOGuvxPxbkc/framework/Source/CPBarPlot.m&l=390

for each bar.

Here are the docs for Core Graphics

http://developer.apple.com/library/ios/#DOCUMENTATION/CoreGraphics/Reference/CoreGraphics_Framework/_index.html

Here’s a place to start

http://developer.apple.com/library/ios/#DOCUMENTATION/GraphicsImaging/Conceptual/drawingwithquartz2d/dq_context/dq_context.html#//apple_ref/doc/uid/TP30001066-CH203-TPXREF101