# Lesson2 Chart Data

範例：<https://github.com/cmmobile/WWChartsDemo>

要建立Chart圖上的資料，此範例以建構出K線圖為目標來介紹。

### 1.建立Entry

```
ChartDataEntry(x: 0, y: 1)
```

一般的線圖、Bar圖在圖面上皆是一個x一個y而k線圖則有開高低收這四個數字

```
CandleChartDataEntry(x: 0, shadowH: 10, shadowL: 0, open: 0, close: 0)
```

建立模擬資料

```swift
private func setData() {
    var enties: [CandleChartDataEntry] = []
    for (i, data) in kDatas.enumerated() {
        let e = CandleChartDataEntry(x: Double(i), shadowH: data.high, shadowL: data.low, open: data.open, close: data.close)
        enties.append(e)
    }
    let set1 = CandleChartDataSet(entries: enties, label: nil)
    let data = CandleChartData(dataSet: set1)
    
    chart.data = data
}
```

一般大部分在公司的Chart X軸代表的都是日期

所以會拿index值直接放入x內再使用限制線去顯示日期

![](https://122733512-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M8xIXKbNapLDOH4MMyQ%2F-MBDt1eYVeSBGR-cuHU5%2F-MBDyHH2RitZqrM_tS-5%2F%E6%88%AA%E5%9C%96%202020-07-02%20%E4%B8%8B%E5%8D%886.00.59.png?alt=media\&token=b6627b6a-f173-4f22-9b0f-c83b845f763d)

### 2.Entry轉換成DataSet

設定資料的樣式讓他有K線的樣子

```swift
private func setDataSet(enties: [CandleChartDataEntry]) -> CandleChartDataSet {
    let dataset = CandleChartDataSet(entries: enties, label: nil)
    dataset.decreasingColor = .green
    dataset.increasingColor = .red
    dataset.decreasingFilled = true
    dataset.increasingFilled = true
    dataset.shadowColorSameAsCandle = true
    return dataset
}
```

![](https://122733512-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M8xIXKbNapLDOH4MMyQ%2F-MBHn_Mb2vBqjC_xkAos%2F-MBHquQsYrFPLm8Fyf9r%2F%E6%88%AA%E5%9C%96%202020-07-03%20%E4%B8%8B%E5%8D%8812.07.15.png?alt=media\&token=50b9af48-e4e3-4b53-af4b-de6279284119)

### 3.DataSet轉換成ChartData

這個步驟主要是有些Charts Data會放好幾個Dataset (例如:多線圖)

K線圖通常就一個Dataset就行了

```swift
let set1 = setDataSet(enties: enties)
let data = CandleChartData(dataSet: set1)
```

### 4.ChartData放入 Charts

```
chart.data = data
```

### 5.補上日期

以同樣的資料源(kDatas)確保index(ChartData x)會對應到相同的kData，再從data裡面的時間字串去加上限制線

```swift
private func setDateLine() {
    for (i, info) in kDatas.enumerated() {
        addDateLimitLine(month: info.time, index: i)
    }
}

///增加限制線(月線)
private func addDateLimitLine(month: String, index: Int) {
    let monthLimitLine = ChartLimitLine(limit: Double(index), label: month)
    monthLimitLine.labelPosition = .bottomLeft
    monthLimitLine.lineWidth = 1
    monthLimitLine.lineColor = .white
    monthLimitLine.valueTextColor = .white
    chart.xAxis.addLimitLine(monthLimitLine)
}
```

![](https://122733512-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M8xIXKbNapLDOH4MMyQ%2F-MBIrtfK39P_YQWNSfk6%2F-MBIs5ZhZX7CZGSsZcpt%2F%E6%88%AA%E5%9C%96%202020-07-03%20%E4%B8%8B%E5%8D%884.51.51.png?alt=media\&token=03a38799-6c14-4526-a23c-e876f97865aa)