Enhancements to ZFPlot

I found Francesco's ZFPlot class on CocoaControls while looking for a lightweight alternative to CorePlot. He had created a nice line-chart plotting custom UIView. While working with it, I realized that it could very easily be extended to basic bar plots and scatter plots. These features have been added. Additionally, some properties of the plots have been migrated to class properties rather than defined constants so that many different kinds of plots can easily be created in the same application. Future users may want to continue this migration so that plots are highly customizable, and such modification is a simple matter of a few find and replace operations.

This first screen shot shows the line plot, bar plot, and scatter plot.

You can also see the isMovement feature illustrated below. When the user touches the plot, the nearest point will be highlighted,
and more precise information given. This feature works for all three kinds of plots

Color, presence of grid lines, type of chart, type of x-axis labeling can all be set dynamically. In particular, a chart's x-axis can either be an index corresponding to the original data's ordering, an NSDate formatted to month/day, or (for scatter plots) the value of the xValue field. Other than scatter plots, the data is plotted with uniform intervals between each point on the x-axis, so for example if you plot dates that are not evenly spaced, this will not be reflected in the x-axis placement of your points.

Also the drawing of the graphs is by default animated, point by point for bar and line charts, and in random clusters for scatter charts. Whether to animate, and the pace of the animation can both be set by a public class property of ZFPlot.

These three plots were created with the following code, which first sets the aesthetic properties:

   CGRect frame = CGRectMake(0, self.height*.15, screenWidth, self.height*.25);
    
    // initialization
    // Line Plot
    self.distancePlot = [[ZFLine alloc] initWithFrame:frame];
    self.distancePlot.units = @"miles";
    self.distancePlot.xAxisLabelType = 1;
    self.distancePlot.stringOffsetHorizontal = 15.0;
    self.distancePlot.baseColorProperty = [UIColor blueColor];
    self.distancePlot.lowerGradientColorProperty = [UIColor redColor];
    self.distancePlot.gridLinesOn = YES;
    [self.view addSubview:self.distancePlot];
    
    // Bar Plot
    frame.origin.y += self.height*.05 + frame.size.height;
    self.timePlot = [[ZFBar alloc] initWithFrame:frame];
    self.timePlot.units = @"seconds";
    self.distancePlot.baseColorProperty = [UIColor blueColor];
    self.timePlot.xAxisLabelType = 0;
    self.timePlot.stringOffsetHorizontal = 5.0;
    self.timePlot.gridLinesOn = YES;
    [self.view addSubview:self.timePlot];
    
    // Scatter Plot
    frame.origin.y += self.height*.05 + frame.size.height;
    self.ratePlot = [[ZFScatter alloc] initWithFrame:frame];
    self.distancePlot.baseColorProperty = [UIColor blueColor];
    self.ratePlot.units = @"hr";
    self.ratePlot.xUnits = @"units";
    self.ratePlot.xAxisLabelType = 2;
    self.ratePlot.stringOffsetHorizontal = 15.0;
    self.ratePlot.gridLinesOn = YES;
    self.ratePlot.scatterRadiusProperty = 3;
    [self.view addSubview:self.ratePlot];

And then finally we generate the plots by providing data:

    // draw data
    [self.distancePlot createChartWith:[self withDatesGenerateDataForNumberPoints:100]]; //to use dates on your x-axis label call withDates...
    [self.timePlot createChartWith:[self generateDataForNumberPoints:20]]; // otherwise use generateData..
    [self.ratePlot createChartWith:[self generateDataForNumberPoints:255]];
    [UIView animateWithDuration:0.5 animations:^{
        self.distancePlot.alpha = 1.0;
        self.timePlot.alpha = 1.0;
        self.ratePlot.alpha = 1.0;
        distanceLabel.alpha = 1.0;
        timeLabel.alpha = 1.0;
        rateLabel.alpha = 1.0;
    }];