Data Source

Description: creating a data source for line chart.

The DataSource.h File

#import <Charting/ChartDataSource.h>
@interface DataSource : NSObject<ChartDataSource>
{
    NSArray *_timestampTitles;
    NSArray *_timestampArray;
    double _yMin;
    double _yMax;
    double _xMin;
    double _xMax;
    double _secondaryYMin;
    double _secondaryYMax;
    double _accumulatedMin;
    double _accumulatedMax;
    double _accumulatedSecondaryMin;
    double _accumulatedSecondaryMax;
    NSMutableArray *data;
}
- (id) init;
- (void) prepare;
@end

The DataSource.m File

#import "DataSource.h"
@implementation DataSource
@synthesize accumulatedMax = _accumulatedMax;
@synthesize accumulatedMin = _accumulatedMin;
@synthesize accumulatedSecondaryMax = _accumulatedSecondaryMax;
@synthesize accumulatedSecondaryMin = _accumulatedSecondaryMin;
@synthesize yMax = _yMax;
@synthesize xMax = _xMax;
@synthesize yMin = _yMin;
@synthesize xMin = _xMin;
@synthesize availableSeriesKeys = _availableSerKey;
@synthesize secondaryYMax = _secondaryYMax;
@synthesize secondaryYMin = _secondaryYMin;
@synthesize timestampArray = _timestampArray;
@synthesize timestampTitles = _timestampTitles;
- (id) init
{
    self = [super init];
    if(self)
    {
        _yMin = 0.0;
        _yMax = 0.0;
        _xMin = 0.0;
        _xMax = 0.0;
        _secondaryYMin = 0.0;
        _secondaryYMax = 0.0;
        _accumulatedMin = 0.0;
        _accumulatedMax = 0.0;
        _accumulatedSecondaryMin = 0.0;
        _accumulatedSecondaryMax = 0.0;
        // Determine data array
        data = [NSMutableArray new];
        // Determine array with X axis labels
        NSMutableArray *tmp = [NSMutableArray new];
        // Generate labels
        for(int i=0;i < 15;i++)
        {
            [tmp addObject:[NSString stringWithFormat:@"%d",i]];
        }
        _timestampTitles = [[NSArray arrayWithArray:tmp] retain];
        _timestampArray = [[NSArray arrayWithArray:tmp] retain];
        // Generate values for data array
        int val;
        for (int i=0; i < 4; i++)
        {
            NSMutableArray *line = [[NSMutableArray new] autorelease];
            for (int j=0;j < 15;j++)
            {
                val = sinf(M_PI * j * 45 / 180)*5*(i+1)+i;
                [line addObject:[NSNumber numberWithInt:val]];
            }
            [data addObject:line];
        }
        return self;
    }
    return nil;
}
// Determine series data
- (NSArray *) seriesDataWithIndex:(int)seriesIndex
{
    return [data objectAtIndex:seriesIndex];
}
// Determine series name displayed in legend
- (NSString *)seriesNameWithIndex:(int)seriesIndex
{
    return [NSString stringWithFormat:@"a%d",seriesIndex];
}
// Calculate maximum and minimum data values
- (void)prepare
{
    for (int i=0; i < data.count; i++)
    {
        for (int j = 0; j < [[data objectAtIndex:0] count]; j++)
        {
            double value = [[[data objectAtIndex:i] objectAtIndex:j] doubleValue];
            if (_yMax < value)
            {
                _yMax = value;
            }
            if (_yMin > value)
            {
                _yMin = value;
            }
        }
        _xMin = 0;
        _xMax = [[data objectAtIndex:0] count];
    }
}
// Determine series headers
- (NSDictionary *) availableSeriesHeaders
{
    return nil;
}
// Determine label for X axis
- (NSString *)xAxisNameForMask:(NSString *)mask
{
    return NSLocalizedString(@"X_AXIS_CAPTION", nil);
}
// Determine label for Y axis
- (NSString *)yAxisNameForMask:(NSString *)mask
{
    return NSLocalizedString(@"Y_AXIS_CAPTION", nil);
}
// Determine label for secondary axis
- (NSString *)secondaryAxisNameForMask:(NSString *)mask
{
    return @"";
}
// Determine minimum and maximum values for all axes
- (double)xMax
{
    return _xMax;
}
- (double) xMin
{
    return _xMin;
}
- (double) yMax
{
    return _yMax;
}
- (double) yMin
{
    return _yMin;
}
- (double)secondaryYMin
{
    return 0.0;
}
- (double)secondaryYMax
{
    return 0.0;
}
- (double)accumulatedSecondaryMin
{
    return 0.0;
}
- (double)accumulatedSecondaryMax
{
    return 0.0;
}
- (int)minTimestamp
{
    return 0;
}
- (int)maxTimestamp
{
    return 0;
}
- (void)setMaxTimestamp:(int)mt{}
- (void)setMinTimestamp:(int)mt{}
- (void)setStartDataIndexOffset:(int)startOffset andEndDataIndexOffset:(int)endOffset{}
-(Brush *)brushForSeries:(int)seriesIndex forTimestamp:(int)ts
{
    return nil;
}
- (NSArray *) availableSeriesKeys
{
    return data;
}
// Determine whether data series is empty
- (BOOL)isEmptySerieWithIndex:(int)index {
    BOOL empty = YES;
    NSArray *seriesData = [self seriesDataWithIndex:index];
    for(NSObject *value in seriesData) {
        if ([value isKindOfClass:[NSNumber class]]) {
            empty = NO;
            break;
        }
    }
    return empty;
}
// Determine whether data series is empty
- (BOOL)isEmptySerieWithIndex:(int)index {
    BOOL empty = YES;
    NSArray *seriesData = [self seriesDataWithIndex:index];
    for(NSObject *value in seriesData) {
        if ([value isKindOfClass:[NSNumber class]]) {
            empty = NO;
            break;
        }
    }
    return empty;
}
@end

See also:

Creating a Line Chart