Draw graph using accelerometer data in core-plot

Question

I'm new to this core-plot framework and trying to draw a line graph based on X and Y acceleration. I can already get my X and Y values and have successfully added core-plot in my project. I'm quite lost on how to start this, so basically, I will have X and Y values and how do I plot this using core-plot? any help is suggested. Thanks!

Answer 1

Maybe my answer is a little bit off topic, as it's not using core-plot, but did you look at the "AccelerometerGraph" sample app provided with Xcode? It provides a nice plot which is dynamically updated while new accelerometer events are registered. The great of this sample is the way CoreAnimation has been used to "speed-up" Quartz2D. And you get all of this using system framework only and no third party code (apart your adaptation of Apple's one).

Answer 2

Look at the Core Plot examples to see how to set up a basic graph. You'll want to use a scatter plot. Call -reloadData on the plot whenever you have new data to display. If only some of the data points change on each frame, you can use the following methods to do a partial update:

-(void)reloadDataInIndexRange:(NSRange)indexRange;
-(void)insertDataAtIndex:(NSUInteger)index
         numberOfRecords:(NSUInteger)numberOfRecords;
-(void)deleteDataInIndexRange:(NSRange)indexRange;

The Real Time Plot in the Plot Gallery example app shows one way to use these methods.