core-plot - coreplot 饼图示例

Question

我正在尝试遵循http://www.raywenderlich.com/13269/how-to-draw-graphs-with-core-plot-part-1上的教程

我正在开发 ios 7 和最新的核心图表库 (1.3)

我正在尝试绘制饼图。我的示例编译得很好，我得到了标题，但我没有绘制任何饼图。我看到的如下所示：

下面给出了包含逻辑的主要源代码。请帮助

//
//  CPDFirstViewController.m
//  CorePlotDemo
//
//  Created by R Menon on 9/19/13.
//  Copyright (c) 2013 4stepfinance Inc. All rights reserved.
//

#import "CPDPieChartViewController.h"

@interface CPDPieChartViewController ()
@property (weak, nonatomic) IBOutlet UIToolbar *toolbar;
@property (weak, nonatomic) IBOutlet UIBarButtonItem *themeButton;

@property (strong, nonatomic) CPTGraphHostingView *hostView;
@property (strong, nonatomic) CPTTheme *selectedTheme;
- (void)initPlot;
-(void)configureHost;
-(void)configureGraph;
-(void)configureChart;
-(void)configureLegend;
@end

@implementation CPDPieChartViewController
#pragma mark - Chart behavior

- (void)initPlot {
    [self configureHost];
    [self configureChart];
    [self configureGraph];
    [self configureLegend];
}

-(void)configureHost {
    // Set up view frame
    CGRect parentRect = self.view.bounds;
    CGSize toolbarSize = self.toolbar.bounds.size;
    parentRect = CGRectMake(parentRect.origin.x, (parentRect.origin.y + toolbarSize.height), parentRect.size.width, (parentRect.size.height - toolbarSize.height));

    // Create host view
    self.hostView = [(CPTGraphHostingView *) [CPTGraphHostingView alloc] initWithFrame:parentRect];
    self.hostView.allowPinchScaling = NO;
    [self.view addSubview:self.hostView];
}

-(void)configureGraph {
    //Create and initialize graph
    CPTGraph *graph = [[CPTXYGraph alloc] initWithFrame:self.hostView.bounds];
    self.hostView.hostedGraph = graph;
    graph.paddingLeft = 0.0f;
    graph.paddingTop = 0.0f;
    graph.paddingRight = 0.0f;
    graph.paddingBottom = 0.0f;
    graph.axisSet = nil;
    // Set up text stile
    CPTMutableTextStyle *textStyle = [CPTMutableTextStyle textStyle];
    textStyle.color = [CPTColor grayColor];
    textStyle.fontName = @"Helvetica-Bold";
    textStyle.fontSize = 16.0f;

    // Configure title
    NSString *title = @"Portfolio Prices: May 1, 2012";
    graph.title = title;
    graph.titleTextStyle = textStyle;
    graph.titlePlotAreaFrameAnchor = CPTRectAnchorTop;
    graph.titleDisplacement = CGPointMake(0.0f, -12.0f);
    // Set theme
    self.selectedTheme = [CPTTheme themeNamed:kCPTPlainWhiteTheme];
    [graph applyTheme:self.selectedTheme];
}

-(void)configureChart {
    // 1 - Get reference to graph
    CPTGraph *graph = self.hostView.hostedGraph;
    // 2 - Create chart
    CPTPieChart *pieChart = [[CPTPieChart alloc] init];
    pieChart.dataSource = self;
    pieChart.delegate = self;
    pieChart.pieRadius = (self.hostView.bounds.size.height * 0.7) / 2;
    pieChart.identifier = graph.title;
    pieChart.startAngle = M_PI_4;
    pieChart.sliceDirection = CPTPieDirectionClockwise;
    // 3 - Create gradient
    CPTGradient *overlayGradient = [[CPTGradient alloc] init];
    overlayGradient.gradientType = CPTGradientTypeRadial;
    overlayGradient = [overlayGradient addColorStop:[[CPTColor blackColor] colorWithAlphaComponent:0.0] atPosition:0.9];
    overlayGradient = [overlayGradient addColorStop:[[CPTColor blackColor] colorWithAlphaComponent:0.4] atPosition:1.0];
    pieChart.overlayFill = [CPTFill fillWithGradient:overlayGradient];
    // 4 - Add chart to graph    
    [graph addPlot:pieChart];
}

-(void)configureLegend {
}

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:YES];
    [self initPlot];
}

- (IBAction)themeTapped:(id)sender {
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#pragma mark - CPTPlotDataSource methods
- (NSUInteger)numberOfRecordsForPlot:(CPTPlot *)plot
{
    return [[[CPDStockPriceStore sharedInstance] tickerSymbols] count];
}

- (NSNumber *)numberForPlot:(CPTPlot *)plot field:(NSUInteger)fieldEnum recordIndex:(NSUInteger)idx
{
    if (CPTPieChartFieldSliceWidth == fieldEnum)
    {
        return [[[CPDStockPriceStore sharedInstance] dailyPortfolioPrices] objectAtIndex:idx];
    }
    return [NSDecimalNumber zero];
}

- (CPTLayer *)dataLabelForPlot:(CPTPlot *)plot recordIndex:(NSUInteger)idx {
    static CPTMutableTextStyle *labelText = nil;
    if (!labelText) {
        labelText= [[CPTMutableTextStyle alloc] init];
        labelText.color = [CPTColor grayColor];
    }
    // 2 - Calculate portfolio total value
    NSDecimalNumber *portfolioSum = [NSDecimalNumber zero];
    for (NSDecimalNumber *price in [[CPDStockPriceStore sharedInstance] dailyPortfolioPrices]) {
        portfolioSum = [portfolioSum decimalNumberByAdding:price];
    }
    // 3 - Calculate percentage value
    NSDecimalNumber *price = [[[CPDStockPriceStore sharedInstance] dailyPortfolioPrices] objectAtIndex:idx];
    NSDecimalNumber *percent = [price decimalNumberByDividingBy:portfolioSum];
    // 4 - Set up display label
    NSString *labelValue = [NSString stringWithFormat:@"$%0.2f USD (%0.1f %%)", [price floatValue], ([percent floatValue] * 100.0f)];
    // 5 - Create and return layer with label text
    return [[CPTTextLayer alloc] initWithText:labelValue style:labelText];
}

-(NSString *)legendTitleForPieChart:(CPTPieChart *)pieChart recordIndex:(NSUInteger)index {
    return @"";
}

#pragma mark - UIActionSheetDelegate methods
- (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex {

}

@end

Answer 1

没关系。我有一个错字：

遵循方法定义

- (void)initPlot {
    [self configureHost];
    [self configureChart];
    [self configureGraph];
    [self configureLegend];
}

应该改为

- (void)initPlot {
    [self configureHost];
    [self configureGraph];
    [self configureChart];
    [self configureLegend];
}

换句话说，我应该在 configureChart 方法之前调用 configureGraph。