ios - 如何在swift3中datePicker索引 Realm 并绘制图表

Question

Swift 3、 Realm 、图表

<小时/>

屏幕上有 DatePicker 和 BarChart

我想要

1) 选择日期 2)索引我的 Realm 数据库 3)绘制条形图

已经有一个 Realm 数据库

<小时/>

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)
}

并绘图(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)
    }

如何修改为根据我选择的日期绘制十个数据

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使用谓词过滤查询结果，请在此处的文档中查看更多信息:https://realm.io/docs/swift/latest/#filtering