ios-linechart

Interactive linecharts for the simplicity-loving iOS developer.

You just want some linecharts, and Core Plot makes you think

Search no more! ios-linechart is here!

Features

Simple API. Lets you draw the first chart by the time you would need to find sample code for Core Plot.
Interactivity. Lets users look at single datapoints.
Support non-uniform steps on the x axis

Installation

CocoaPods

The best way to get ios-linechart is to use CocoaPods.

Without CocoaPods

If, for some reason, you don't want that, copy the following files into your project:

LegendView.h, LegendView.m
LineChartView.h, LineChartView.m
InfoView.h, InfoView.m

Additionally, you will need to get some dependencies from the objc-utils project:

UIKit+DrawingHelpers.{h,m} (found in UIKit/Drawing/)

Just copy these into you project as well.

ios-linechart uses Core Graphics, so you'll need to add CoreGraphics.framework to your project.

Usage

Basic usage can be seen in the demo app contained in the repository.

First, import the main header:

    #import "LineChartView.h"

Each chart line is contained in a LineChartData object, which specifies a range of its data on the x axis (xMin / xMax), a color, a title (which is displayed in the legend) and an itemCount, the number of data points:

    LineChartData *d = [LineChartData new];
    d.xMin = 1;
    d.xMax = 31;
    d.title = @"The title for the legend";
    d.color = [UIColor redColor];
    d.itemCount = 10;

Additionally, each LineChartData object also has a getData property. This is simply a block that takes the number of a data point as its argument and returns LineChartDataItem objects, which wrap the individual data points:

    NSMutableArray *vals = [NSMutableArray new];
    for(NSUInteger i = 0; i < d.itemCount; ++i)
        [vals addObject:@((rand() / (float)RAND_MAX) * (31 - 1) + 1)];
    [vals sortUsingComparator:^NSComparisonResult(id obj1, id obj2) {
        return [obj1 compare:obj2];
    }];
    d.getData = ^(NSUInteger item) {
        float x = [vals[item] floatValue];
        float y = powf(2, x / 7);
        NSString *label1 = [NSString stringWithFormat:@"%d", item];
        NSString *label2 = [NSString stringWithFormat:@"%f", y];
        return [LineChartDataItem dataItemWithX:x y:y xLabel:label1 dataLabel:label2];
    };

The x and y properties of LineChartDataItem are, obviously, the x and y values of the data point. xLabel is the text displayed on the x axis when the data point is selected, dataLabel is usually just a textual representation of the y value, and is displayed in a bubble directly next to the data point when the user touches it.

Note that, to get a coherent chart, the x values for the items should be sorted. This will be the case anyway for most real-world data.

Finally, everything is packed up into a LineChartView:

    LineChartView *chartView = [[LineChartView alloc] initWithFrame:CGRectMake(20, 700, 500, 300)];
    chartView.yMin = 0;
    chartView.yMax = powf(2, 31 / 7) + 0.5;
    chartView.ySteps = @[@"0.0",
                         [NSString stringWithFormat:@"%.02f", chartView.yMax / 2],
                         [NSString stringWithFormat:@"%.02f", chartView.yMax]];
    chartView.data = @[d];

    [self.view addSubview:chartView];

The yMin and yMax properties should be self-evident. ySteps is an array of labels which are placed along the y axis. data is an array of all LineChartData objects to use. drawsDataPointOrnaments is a switch that determines whether circles are drawn around the actual data points.

Screenshots

Contact

Bug reports and pull requests are welcome! Contact me via e-mail or just by opening an issue on GitHub.

code4app/ios-linechart