Bert McDowell

This is a custom line graph written in Objective-C using a standard UIView as a base class. The Graph is rendered inside an overloaded drawRect function using CGContext to render the graph and all it’s components.

Features:
• Positive Graph Rendering.
• Positive / Negative Graph Rendering.
• Basic line rendering.
• Background Image support.
• Font selection.
• Label support.
• Title support.
• Hide / Show Scale.

Improvements and Additions:
• The drawRect function needs to be tidied up, but it’s fine if you just want to use the class.
• The graph code needs to be improved to support totally negative graph values.
• I would like to extend the line rendering to be a bit more flexibility.
• Support for key graph points would be nice addition.

Warning’s :
• Watch the length of your string’s and font size’s as the current implementation does not re-size fonts and these may overlap.
• I don’t recommend this implementation if you wish to animate the graph, I’ve found that causing the view to redraw is expensive.

Source:

//
//  LineGraph.h
//
//  Created by Robert on 04/10/2009.
//

#import <UIKit/UIKit.h>

typedef enum
{
LineGraphOrientationUnknown,
LineGraphOrientationPortrait,            // Device oriented vertically, home button on the bottom
LineGraphOrientationPortraitUpsideDown,  // Device oriented vertically, home button on the top
LineGraphOrientationLandscapeLeft,       // Device oriented horizontally, home button on the right
LineGraphOrientationLandscapeRight,      // Device oriented horizontally, home button on the left
} LineGraphOrientation;

// --------------------------------------------------------
// The Line Object
// --------------------------------------------------------
@interface Line : NSObject
{
@private
NSString *			name;
NSMutableArray *	values;
UIColor *			color;
float				width;
Boolean				dashed;
}

@property (nonatomic, readonly) NSString *			name;
@property (nonatomic, readonly) NSMutableArray *	values;
@property (nonatomic, retain)   UIColor *			color;
@property (nonatomic)			float				width;
@property (nonatomic)			Boolean				dashed;

- (id) initWithName:(NSString*)_name AndColor:(UIColor*)_color AndWidth:(float)_width;
- (id) initWithName:(NSString*)_name AndColor:(UIColor*)_color AndWidth:(float)_width SetDashed:(Boolean)_dashed;

- (void) add:(float)_value;
- (void) clear;

@end

@interface LineGraph : UIView
{
@private

// --------------------------------
// Background Image :
// will be rendered if not nil.
// --------------------------------
UIImage *		 backgroundImage;
// --------------------------------

// --------------------------------
// Work out the Graph Values
// --------------------------------
NSInteger		 minNumEntries;
NSInteger		 peakEntries;
float			 maxValue;
float			 minValue;
NSInteger		 totalEntries;
float			 totalValue;
// --------------------------------

// --------------------------------
// Data Array :
// Contains the bar objects.
// --------------------------------
NSMutableArray * values;

NSString *		 title;
NSString *		 verticalAxisName;
NSString *		 horizontalAxisName;

LineGraphOrientation orientation;
// --------------------------------

// --------------------------------
// Graph Indent :
// How much away from the edges
// does the graph get rendered.
// --------------------------------
CGSize			indent;
UIFont *		font;
UIFont *		fontSmall;
UIColor	*		fontColor;
// --------------------------------

// --------------------------------
// line settings :
// --------------------------------
NSInteger		lineWidth;
UIColor *		lineColor;
// --------------------------------

// --------------------------------
// grid data
// --------------------------------
NSInteger		gridLineWidth;
UIColor *		gridLineColor;
// --------------------------------

// --------------------------------
// Fill data
// --------------------------------
UIColor *		fillColor;
// --------------------------------

// --------------------------------
// line values
// --------------------------------
float			lineHighlightPercentage;
UIColor *		lineHighlightColor;

CGPoint			lineShadowOffset;
UIColor *		lineShadowColor;
// --------------------------------

// --------------------------------
// Render Flags :
// Indicate the parts of the line
// to render.
// --------------------------------
Boolean			drawGrid;
Boolean			drawEdge;
Boolean			drawLine;
Boolean			drawFill;
Boolean			drawScale;
Boolean			drawKey;
// -------------------------------

}
@property (nonatomic, readonly)	NSInteger count;

@property (nonatomic, retain)	UIImage * backgroundImage;
@property (nonatomic, copy)		NSString * title;
@property (nonatomic, copy)		NSString * verticalAxisName;
@property (nonatomic, copy)		NSString * horizontalAxisName;
@property (nonatomic) LineGraphOrientation orientation;

@property (nonatomic)			CGSize indent;
@property (nonatomic, retain)	UIFont * font;
@property (nonatomic, retain)	UIFont * fontSmall;
@property (nonatomic, retain)	UIColor	* fontColor;
@property (nonatomic)			NSInteger lineWidth;
@property (nonatomic, retain)	UIColor * lineColor;
@property (nonatomic)			NSInteger gridLineWidth;
@property (nonatomic, retain)	UIColor * gridLineColor;
@property (nonatomic, retain)	UIColor * fillColor;
@property (nonatomic)			float lineHighlightPercentage; // 0 - 1 value;
@property (nonatomic, retain)	UIColor * lineHighlightColor;
@property (nonatomic)			CGPoint lineShadowOffset;
@property (nonatomic, retain)	UIColor * lineShadowColor;

@property (nonatomic)			Boolean drawGrid;
@property (nonatomic)			Boolean drawEdge;
@property (nonatomic)			Boolean drawLine;
@property (nonatomic)			Boolean	drawFill;
@property (nonatomic)			Boolean drawScale;
@property (nonatomic)			Boolean drawKey;

// remove all the current lines
- (void) removeAllLines;
- (void) removeLineAtIndex:(NSInteger)_index;
- (void) removeLineWithName:(NSString*)_name;
- (void) removeLine:(Line*)_line;

// add a line
- (Line*) addLineWithName:(NSString*)_name WithColor:(UIColor*)_color AndWidth:(float)_width;
- (Line*) addLineWithName:(NSString*)_name WithColor:(UIColor*)_color AndWidth:(float)_width SetDashed:(Boolean)_dashed;

// retrieve the line
- (Line*) lineAtIndex:(NSInteger)_index;
- (Line*) lineWithName:(NSString*)_name;

@end

The code is provided as is, use at your own risk.

Source Code : LineGraph.h, LineGraph.m

Sample Project : LineGraphSample