过分拥挤的标签在饼图和条形图中是不可读的(Overcrowded labels are unreadable in piechart and barcharts)

 对于PieCharts，通常有几个“切片”只包含很小一部分数据（例如<2％），结果是标签相互重叠并且不可读，显示如下。 有谁知道这个解决方案？ 我看到一些图表显示了饼图之外的标签，并指向了相应的部分，但我不确定ios图表是否有类似的可能。 
 
  
 
 对于条形图也会出现类似的问题，其中所有值彼此重叠并且变得不可读，如下所示。 我能想到的解决方案是仅显示一部分条形图，并在用户平移时显示其他条形图。 
 
  
 
 如果有人处理了这两个问题，我会很高兴看到你如何解决问题，或者如果最好使用不同的库。 我在下面发布了一些代码，但不知道它是否会有帮助，因为这可能不是真正的实现错误。 
 
 条形图 
 
    //...init view...
    _chartView.delegate = self;
    _chartView.descriptionText = @"";
    _chartView.noDataTextDescription = @"No data";
    _chartView.drawHighlightArrowEnabled = true;
    _chartView.drawValueAboveBarEnabled = YES;
    _chartView.drawMarkers = true;
    _chartView.dragEnabled = true;


    ChartXAxis *xAxis = _chartView.xAxis;
    xAxis.labelPosition = XAxisLabelPositionBottom;
    xAxis.labelFont = [UIFont systemFontOfSize:10.f];
    xAxis.drawGridLinesEnabled = NO;
    xAxis.spaceBetweenLabels = 2.0;

    ChartYAxis *rightAxis = _chartView.rightAxis;
    rightAxis.enabled = NO;

    NSMutableArray *yVals = [[NSMutableArray alloc] init];
    NSMutableArray *xVals = [[NSMutableArray alloc] init];

    //populate xVals and yVals with data..

    BarChartDataSet *set1 = [[BarChartDataSet alloc] initWithYVals:yVals label:@"Occurences"];
    set1.colors = ChartColorTemplates.vordiplom;
    set1.drawValuesEnabled = YES;

    NSMutableArray *dataSets = [[NSMutableArray alloc] init];
    [dataSets addObject:set1];
    BarChartData *bdata = [[BarChartData alloc] initWithXVals:xVals dataSets:dataSets];
    [bdata setValueFont:[UIFont fontWithName:@"HelveticaNeue-Light" size:10.f]];

    _chartView.data = bdata;

    [self.view addSubview:_chartView];
 
 饼形图 
 
 // init饼图.. _pieChart.delegate = self; 
 
_pieChart.usePercentValuesEnabled = YES;
_pieChart.descriptionText = @"";
_pieChart.drawCenterTextEnabled = YES;

NSMutableArray *yVals = [[NSMutableArray alloc] init];
NSMutableArray *xVals = [[NSMutableArray alloc] init];

//...populate xVals and yVals with data 

PieChartDataSet *dataSet = [[PieChartDataSet alloc] initWithYVals:yVals label:@"Locations"];
dataSet.sliceSpace = 2.0;

dataSet.colors = ChartColorTemplates.joyful;
PieChartData *data1 = [[PieChartData alloc] initWithXVals:xVals dataSet:dataSet];
NSNumberFormatter *pFormatter = [[NSNumberFormatter alloc] init];
pFormatter.numberStyle = NSNumberFormatterPercentStyle;
pFormatter.maximumFractionDigits = 1;
pFormatter.multiplier = @1.f;
pFormatter.percentSymbol = @" %";
[data1 setValueFormatter:pFormatter];
_pieChart.data = data1;
[self.view addSubview:_pieChart];

For PieCharts, there are often several "slices" with a very small portion of the data (< 2%, for example), and as a result, the labels overlap each other and are unreadable, displayed below. Does anyone know solutions to this? I've seen some charts that show the label outside the pie and point to the respective piece, but I'm not sure if something similar is possible for ios-charts.
 
 
A similar issue occurs for bar charts, in which all the values overlap with each other and become unreadable, shown below. The solution I can think of, would be to show only a subset of the bars, and show the other bars if the user pans.
 
 
If anyone has dealt with either issue, I'd appreciate seeing how you solved it, or if it's better to use a different library. I posted some code below, but not sure if it''ll help, since this presumably isn't really an implementation bug.
 
Bar Chart
 
    //...init view...
    _chartView.delegate = self;
    _chartView.descriptionText = @"";
    _chartView.noDataTextDescription = @"No data";
    _chartView.drawHighlightArrowEnabled = true;
    _chartView.drawValueAboveBarEnabled = YES;
    _chartView.drawMarkers = true;
    _chartView.dragEnabled = true;


    ChartXAxis *xAxis = _chartView.xAxis;
    xAxis.labelPosition = XAxisLabelPositionBottom;
    xAxis.labelFont = [UIFont systemFontOfSize:10.f];
    xAxis.drawGridLinesEnabled = NO;
    xAxis.spaceBetweenLabels = 2.0;

    ChartYAxis *rightAxis = _chartView.rightAxis;
    rightAxis.enabled = NO;

    NSMutableArray *yVals = [[NSMutableArray alloc] init];
    NSMutableArray *xVals = [[NSMutableArray alloc] init];

    //populate xVals and yVals with data..

    BarChartDataSet *set1 = [[BarChartDataSet alloc] initWithYVals:yVals label:@"Occurences"];
    set1.colors = ChartColorTemplates.vordiplom;
    set1.drawValuesEnabled = YES;

    NSMutableArray *dataSets = [[NSMutableArray alloc] init];
    [dataSets addObject:set1];
    BarChartData *bdata = [[BarChartData alloc] initWithXVals:xVals dataSets:dataSets];
    [bdata setValueFont:[UIFont fontWithName:@"HelveticaNeue-Light" size:10.f]];

    _chartView.data = bdata;

    [self.view addSubview:_chartView];
 
Pie Chart
 
//init pie chart.. _pieChart.delegate = self;
 
_pieChart.usePercentValuesEnabled = YES;
_pieChart.descriptionText = @"";
_pieChart.drawCenterTextEnabled = YES;

NSMutableArray *yVals = [[NSMutableArray alloc] init];
NSMutableArray *xVals = [[NSMutableArray alloc] init];

//...populate xVals and yVals with data 

PieChartDataSet *dataSet = [[PieChartDataSet alloc] initWithYVals:yVals label:@"Locations"];
dataSet.sliceSpace = 2.0;

dataSet.colors = ChartColorTemplates.joyful;
PieChartData *data1 = [[PieChartData alloc] initWithXVals:xVals dataSet:dataSet];
NSNumberFormatter *pFormatter = [[NSNumberFormatter alloc] init];
pFormatter.numberStyle = NSNumberFormatterPercentStyle;
pFormatter.maximumFractionDigits = 1;
pFormatter.multiplier = @1.f;
pFormatter.percentSymbol = @" %";
[data1 setValueFormatter:pFormatter];
_pieChart.data = data1;
[self.view addSubview:_pieChart];

原文：https://stackoverflow.com/questions/34881917