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，方法是在X轴上传递时间值，在Y轴上传递表示货币金额的整数值。

因为时间值在一个有限的时间间隔内，所以我试图将它限制为7个元素，我首先将其转换为unix，并检查其中是否有一个是最旧的，然后从较新的元素中替换较旧的元素，因此我得到NSNumbers的数组。

下面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;
}

下面是我的助手方法：

+ (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数据为：

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

yVals数组是：

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

该图显示为：

​

​

现在，Y轴看起来和预期的一样，但是Y轴不正确，因为点之间的间距是相等的，你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]];

通过给出一个不同的xIndex，但图形完全停止在屏幕上显示。

提前感谢您的所有建设性回答:)

Answer 1

我假设你的意思是"X轴不正确，因为点之间的间距是相等的，你知道我做错了什么吗？“

这是设计好的。要解决此问题，您需要插入x轴的中间日期值，而不是为指定的xIndex插入任何数据条目。这个问题已经在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]];
    }
}