Implementing a Simple Line Graph in iOS - objective-c

Question

What would be the best way to implament a simple line graph inside my iPad app. Im only looking to plot 4-8 points and the graph does need to be fancy looking. HTML5 will be good enough to use for what I need.
How would I go about implementing HTML code to plot a line graph?
I have been looking at using Google Charting Tools, but any other suggestions that I could use?

Answer 1

Here is a very basic class that will give you the basic line. It takes an NSArray of NSNumbers for the Y axis. It should provide a good starting point for you as it is as simple as it gets. You might consider adding labels to the points and axis markers to give a sense of scale.
Header:
#import <UIKit/UIKit.h>
#interface SOGenericGraphView : UIView {
NSArray *yValues;
}
#property (strong, atomic) NSArray *yValues;
#end
Implementation:
#import "SOGenericGraphView.h"
#implementation SOGenericGraphView
#synthesize yValues;
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
self.backgroundColor = [UIColor whiteColor];
}
return self;
}
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
// Drawing code
[super drawRect:rect];
CGRect insetRect = CGRectInset(self.frame, 10, 15);
double maxSpeed = [[yValues valueForKeyPath:#"#max.doubleValue"] doubleValue];
CGFloat yRatio = insetRect.size.height/maxSpeed;
CGFloat xRatio = insetRect.size.width/(yValues.count-1);
UIBezierPath *sparkline = [UIBezierPath bezierPath];
for (int x = 0; x< yValues.count; x++) {
CGPoint newPoint = CGPointMake(x*xRatio + insetRect.origin.x, insetRect.size.height - (yRatio*[[yValues objectAtIndex:x] doubleValue] - insetRect.origin.y));
if (x == 0) {
[sparkline moveToPoint:newPoint];
}
else {
[sparkline addLineToPoint:newPoint];
}
}
[[UIColor redColor] set];
[sparkline stroke];
}
#end