如何在swift3中datePicker索引领域和绘制图表

Question

Swift 3，领域，图表

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一个屏幕有一个 DatePicker 和 BarChart

我想要

1) 选择一个日期 2）索引我的领域数据库 3) 绘制条形图

已经有一个领域数据库

---

为了精确索引，我将日期分隔为 YYYY~mm

class ChartsDatas: Object {
dynamic var date: Date = Date()

let dateYYYYFormat = DateFormatter()
let dateMMFormat = DateFormatter()
let dateddFormat = DateFormatter()
let datehhFormat = DateFormatter()
let datemmFormat = DateFormatter()
dynamic var dateYYYY: String = "2000"
dynamic var dateMM: String = "01"
dynamic var datedd: String = "01"
dynamic var datehh: String = "00"
dynamic var datemm: String = "00"

dynamic var count: Double = Double(0.0)

func dateLongToShort(orgDate:Date!){
    dateYYYYFormat.dateFormat = "YYYY"
    dateYYYY = dateYYYYFormat.string(from: orgDate)

    dateMMFormat.dateFormat = "MM"
    dateMM = dateMMFormat.string(from: orgDate)

    dateddFormat.dateFormat = "dd"
    datedd = dateddFormat.string(from: orgDate)

    datehhFormat.dateFormat = "hh"
    datehh = datehhFormat.string(from: orgDate)

    datemmFormat.dateFormat = "mm"
    datemm = datemmFormat.string(from: orgDate)
}

并绘制（此方法是绘制最新的十个数据）

    var dataEntries: [BarChartDataEntry] = []
    let visitorCounts = getVisitorCountsFromDatabase() //read realm DB here

    var xAxisCount = visitorCounts.count 
    if xAxisCount > 10{
        xAxisCount = visitorCounts.count - 10
    }
    for i in xAxisCount..<visitorCounts.count {
        let timeIntervalForDate: TimeInterval = visitorCounts[i].date.timeIntervalSince1970
        let dataEntry = BarChartDataEntry(x: Double(timeIntervalForDate), y: Double(visitorCounts[i].count))
        dataEntries.append(dataEntry)
    }

如何根据我选择的日期修改为绘制十个数据

谢谢

Answer 1

我不确定getVisitorCountsFromDatabase() 中发生了什么，但您可以通过指定日期间隔来过滤带有谓词的查询结果，请参阅此处的文档：https://realm.io/docs/swift/latest/#filtering