ios - 使用 danielgindi/ios-charts 库创建折线图

Question

我正在尝试使用 danielgindi/ios-charts library 创建折线图通过在 X 轴上传递时间值和在 Y 轴上传递表示货币金额的整数值。

时间值，因为它在一个有限的区间内，因为我试图将它限制为 7 个元素，我首先将它转换为 unix 并检查其中一个是最旧的，然后我用较新的替换旧的所以我得到了 NSNumbers 数组。

这里是我的代码和数组数据:

- (void)addChartWithArray:(NSArray *)dataArray{

    NSMutableArray *xVals = [[NSMutableArray alloc] init];
    NSMutableArray *yVals = [[NSMutableArray alloc] init];
    int maxNumberOfValuesInGraph;
    if(dataArray.count >= 7){
        maxNumberOfValuesInGraph = (int)dataArray.count - 7;
    }else{
        maxNumberOfValuesInGraph = 0;
    }

    for (int cout = maxNumberOfValuesInGraph; cout < dataArray.count; cout++){
        TRTargetEstimation *targetEstimation = [dataArray objectAtIndex: cout];
        [xVals addObject:[targetEstimation dateCreated]];
    }

    xVals = [self calculateTimeValues: xVals];
    int secondCounter = 0;
    for (int cout = maxNumberOfValuesInGraph; cout < dataArray.count; cout++) {
        TRTargetEstimation *targetEstimation = [dataArray objectAtIndex: cout];
        [yVals addObject:[[ChartDataEntry alloc] initWithValue:[targetEstimation.estimationValue floatValue] xIndex:secondCounter]];
        secondCounter++;
    }

    LineChartDataSet *set1 = [[LineChartDataSet alloc] initWithYVals:yVals label:@"DataSet 1"];

    set1.lineWidth = 2.f;
    set1.circleRadius = 6.0;
    [set1 setColor: [UIColor orangeColor]];
    [set1 setCircleColor:[UIColor orangeColor]];
    set1.highlightColor = [UIColor orangeColor];
    set1.drawValuesEnabled = YES;

    LineChartData *data = [[LineChartData alloc] initWithXVals:xVals dataSet:set1];
    [data setValueFont:[UIFont fontWithName:@"HelveticaNeue-Light" size:7.f]];


    self.lineChartView.minOffset = 0;
    self.lineChartView.delegate = self;
    self.lineChartView.backgroundColor = [UIColor clearColor];

    self.lineChartView.descriptionText = @"";
    self.lineChartView.noDataTextDescription = @"No history available.";

    self.lineChartView.drawGridBackgroundEnabled = NO;
    self.lineChartView.dragEnabled = NO;
    [self.lineChartView setScaleEnabled:NO];
    self.lineChartView.pinchZoomEnabled = NO;
    [self.lineChartView setViewPortOffsetsWithLeft:10.0 top:0.0 right:10.0 bottom:0.0];

    self.lineChartView.legend.enabled = NO;

    self.lineChartView.leftAxis.enabled = NO;
    self.lineChartView.rightAxis.enabled = NO;
    self.lineChartView.xAxis.enabled = NO;

    self.lineChartView.data = data;

    self.lineChartView.hidden = YES;
    self.leftLineView.hidden = YES;
    self.bottomLineView.hidden = YES;

}

- (NSMutableArray *)calculateTimeValues:(NSMutableArray *)passedArray {
    NSMutableArray *returnedArray = [[NSMutableArray alloc] init];

    for (int count = 0; count < passedArray.count; count++) {

        NSDate *date = [TRUtils getDateOutOfString:[passedArray objectAtIndex:count]
                                     andDateFormat:@"yyyy-MM-dd HH:mm:ss"];
        [returnedArray addObject:[NSNumber numberWithInt:[TRUtils getUNIXTimeFromDate:date]]];

    }

    [returnedArray sortUsingDescriptors:[NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"self" ascending:YES]]];

    int minValue = [[returnedArray firstObject] intValue];
    for (int count = 0; count < passedArray.count; count++) {
        [returnedArray replaceObjectAtIndex:count
                               withObject:[NSString stringWithFormat:@"%d",[[returnedArray objectAtIndex:count] intValue] - minValue]];
    }

    return returnedArray;
}

这是我的辅助方法:

+ (NSDate *)getDateOutOfString:(NSString *)passedString andDateFormat:(NSString *)dateFormat{

    NSString *dateString = passedString;
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:dateFormat];
    NSDate *dateFromString = [[NSDate alloc] init];
    dateFromString = [dateFormatter dateFromString:dateString];
    return dateFromString;

}

+ (int)getUNIXTimeFromDate:(NSDate *) datePassed{

    return (int)[datePassed timeIntervalSince1970];

}

xVals 数据是:

<__NSArrayM 0x7fca4b775dd0>(
0,
213,
298,
435,
524,
591,
664
)

yVals 数组是:

[234234,
123123,
2223355,
22222222,
2342,
121212,
121212]

图形显示为:

现在，Y 轴看起来符合预期，但 Y 轴不正确，因为点之间的间距相等，知道我做错了什么吗？

我已经尝试更改下一行:

[yVals addObject:[[ChartDataEntry alloc] initWithValue:[targetEstimation.estimationValue floatValue] xIndex:secondCounter]];

通过提供不同的 xIndex，但图表完全停止显示在屏幕上。

提前感谢所有建设性的回答:)

Answer 1

我假设您的意思是“X 轴不正确，因为点之间的间距相等，知道我做错了什么吗？”

这是设计使然。要解决此问题，您需要为 x 轴插入中间日期值，但不为特定 xIndex 插入任何数据条目。这已经在 github 页面上被问到了。

您必须为 [self hasDataAtIndex:cout] 编写自己的逻辑

for (int cout = maxNumberOfValuesInGraph; cout < dataArray.count; cout++){
    TRTargetEstimation *targetEstimation = [dataArray objectAtIndex: cout];
    [xVals addObject:[targetEstimation dateCreated]];

    if ([self hasDataAtIndex:cout]) {
        [yVals addObject:[[ChartDataEntry alloc] initWithValue:[targetEstimation.estimationValue floatValue] xIndex:cout]];
    }
}