The main plot with a month on the x axis (iphone)

Question

I would like to draw an XY plot using coreplot on an iphone with a date on the x axis and some values ​​on the y axis. Referring to the DatePlot example sent with the coreplot SDK, I was able to draw a graph with a date along the x axis on a monthly scale (i.e., X varies from 1 date of the month to the last date). Now I want the annual scale, that is, I want to show all the monthly names (January, February, March, etc.) along the x axis, and my tick is one month.

I used the following code to display the values ​​in the monthly scale

oneXUnit        =   60 * 60 * 24;
x.majorIntervalLength    =  CPDecimalFromFloat((float) oneXUnit);
NSDateFormatter *dateFormatter   =   [[[NSDateFormatter alloc] init]autorelease];
NSString *dateString        =   @"0";
[dateFormatter setDateFormat:@"MM"];
CPTimeFormatter *timeFormatter  =   [[CPTimeFormatter alloc]initWithDateFormatter:dateFormatter];
timeFormatter.referenceDate =   [dateFormatter dateFromString:dateString];
x.labelFormatter    =   timeFormatter;

Now for annual mode x tick inteval should be one month. I tried the code below but didn't work

oneXUnit        =   60 * 60 * 24 * 30;
x.majorIntervalLength    =  CPDecimalFromFloat((float) oneXUnit);
NSDateFormatter *dateFormatter   =   [[[NSDateFormatter alloc] init]autorelease];
NSString *dateString        =   @"Jan";
[dateFormatter setDateFormat:@"MMM"];
CPTimeFormatter *timeFormatter  =   [[CPTimeFormatter alloc]initWithDateFormatter:dateFormatter];
timeFormatter.referenceDate =   [dateFormatter dateFromString:dateString];
x.labelFormatter    =   timeFormatter;   

I think this logic fails because the number of days for each month is different. Now the months are displayed on the x axis, but it is displayed as

Jan, , , , , , , , , , ,

, , 2 . . ? ,

Answer 1

. , , .

x.labelingPolicy = CPAxisLabelingPolicyNone;

NSMutableArray *customLabels = [NSMutableArray arrayWithCapacity:12];
NSMutableArray *customMajorTickLocations = [NSMutableArray arrayWithCapacity:12];
NSMutableArray *customMinorTickLocations = [NSMutableArray arrayWithCapacity:12];
NSDate* dateCurrentMonth = [[NSDate date] dateAtStartOfYear];

for (NSUInteger iMonth = 0; iMonth < 12; iMonth++)
{
    NSNumber* numMajorTickLocation = [NSNumber numberWithDouble:[dateCurrentMonth timestampAtMidnight]];
    NSNumber* numMinorTickLocation = [NSNumber numberWithDouble:[dateCurrentMonth timestampAtMidnight]+14*oneDay];

CPAxisLabel *newLabel = [[CPAxisLabel alloc] initWithText:[dateFormatter stringFromDate:dateCurrentMonth] textStyle:x.labelTextStyle];
newLabel.tickLocation = [numMinorTickLocation decimalValue];
newLabel.offset = x.labelOffset + x.majorTickLength;

dateCurrentMonth = [[dateCurrentMonth dateByAddingDays:32] dateAtStartOfMonth];

[customLabels addObject:newLabel];
[customMajorTickLocations addObject:numMajorTickLocation];
[customMinorTickLocations addObject:numMinorTickLocation];
[newLabel release];

}

// add a last major tick to close the range
[customMajorTickLocations addObject:[NSNumber numberWithDouble:[dateCurrentMonth timestampAtMidnight]]];

x.axisLabels = [NSSet setWithArray:customLabels];
x.majorTickLocations = [NSSet setWithArray:customMajorTickLocations];
x.minorTickLocations = [NSSet setWithArray:customMinorTickLocations];

Answer 2

. CPTCalendarFormatter CPTTimeFormatter, , (, = 60 * 60, = 24 * 60 * 60), / (30 * 24 * 60 * 60 31 * 24 * 60 * 60, 28, ..). CPTCalendarFormatter . , , , .

, .

DidLoad :

[...]

// Graph host view
CPTGraphHostingView* hostView = [[CPTGraphHostingView alloc] initWithFrame:self.view.frame];
[self.view addSubview: hostView];

// Your graph
CPTGraph* graph = [[CPTXYGraph alloc] initWithFrame:hostView.bounds];
hostView.hostedGraph = graph;
CPTXYAxisSet *axisSet = (CPTXYAxisSet *)[graph axisSet];    

// xAxis configuration
CPTXYAxis *xAxis = [axisSet xAxis];
[xAxis setLabelingPolicy:CPTAxisLabelingPolicyFixedInterval];
// Prepare dateFormat for current Locale, we want "JAN 2014" "FEB 2014" and so on
NSString *dateComponents = @"MMMYY";
NSString *localDateFormat = [NSDateFormatter dateFormatFromTemplate:dateComponents options:0 locale:[NSLocale currentLocale]];
NSDateFormatter *labelDateFormatter=[[NSDateFormatter alloc] init];
labelDateFormatter.dateFormat=localDateFormat;    
// Set xAxis date Formatter
CPTCalendarFormatter *xDateYearFormatter = [[CPTCalendarFormatter alloc] initWithDateFormatter:labelDateFormatter];
//Keep in mind this reference date, it will be used to calculate NSNumber in dataSource method
xDateYearFormatter.referenceDate = [NSDate dateWithTimeIntervalSince1970:0];
xDateYearFormatter.referenceCalendarUnit=NSMonthCalendarUnit;    
[xAxis setLabelFormatter:xDateYearFormatter];

// yAxis configuration
CPTXYAxis *yAxis = [axisSet yAxis];
[yAxis setMajorIntervalLength:CPTDecimalFromFloat(_YOURYINTERVAL_)];
[yAxis setLabelingPolicy:CPTAxisLabelingPolicyFixedInterval];
[yAxis setLabelFormatter:_YOURYFORMATTER_];
[yAxis setAxisConstraints:[CPTConstraints constraintWithLowerOffset:0.0]]

// Get the (default) plotspace from the graph so we can set its x/y ranges
CPTXYPlotSpace *plotSpace = (CPTXYPlotSpace *) graph.defaultPlotSpace;
NSDate *startDate=_YOURSTARTINGDATE_
//Number of months since the reference date
NSInteger xStart=[[[NSCalendar currentCalendar] components: NSCalendarUnitMonth
                                 fromDate: xDateYearFormatter.referenceDate
                                   toDate: _YOURSTARTINGDATE_
                                  options: 0] month];    
[plotSpace setXRange: [CPTPlotRange plotRangeWithLocation:CPTDecimalFromInteger(xStart)     length:CPTDecimalFromInteger(_YOURDATESARRAY_.count-1)]];
[plotSpace setYRange: [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(0.0) length:CPTDecimalFromFloat(_YOURMAXYVALUE_)]];

[...]

:

 -(NSNumber *)numberForPlot:(CPTPlot *)plot field:(NSUInteger)fieldEnum recordIndex:(NSUInteger)index
{
    switch (fieldEnum) {

        case CPTScatterPlotFieldX: {

            NSInteger monthsOffset=[[[NSCalendar currentCalendar] components: NSCalendarUnitMonth  fromDate: [NSDate dateWithTimeIntervalSince1970:0] toDate: [_YOURDATESARRAY_ objectAtIndex:index] options: 0] month];                
            NSNumber *val = [NSNumber numberWithInteger:monthsOffset];    
            return val;
            break;
        }
        case CPTScatterPlotFieldY: {
            NSNumber *val=_YOURVALUEFORYAXIS_;
            return val;
            break;
        }
        default:
            break;
    }

    return nil;
}