Question

我正在尝试设计一个ios应用程序以在折线图中显示json数据。

首先，这是我的json数据。

{
TH_5min: [
{
Data: "2019-02-23T00:00:00",
Time: "11:00:00",
XTP_A: 10.5, //temperature 1
XHP_A: 11.5, //humidity 1
XTP_B: 33.5,
XHP_B: 44.6,
XTP_C: 88.9,
XHP_C: 66.6,
XTP_D: 77.9,
XHP_D: 99.6,
XTP_E: 87.87,
XHP_E: 66.66
},
{
Data: "2019-02-23T00:00:00",
Time: "11:05:00",
XTP_A: 55.2,  //temperature 1
XHP_A: 44.3,  //humidity 1
XTP_B: 66.6,
XHP_B: 77.87,
XTP_C: 87.77,
XHP_C: 87.87,
XTP_D: 8.87,
XHP_D: 78.78,
XTP_E: 87.78,
XHP_E: 87.87
}
]
}

这是我对显示json数据的快速代码的实现。

override func viewDidLoad() {
        super.viewDidLoad()
      apiip = APIip
        getlatestTh_5min()
    @objc func getlatestTh_5min(){
        guard let th_5minUrl = URL(string: "http://" + apiip + "/api/Th_5min") else{
            return
        }
        let request = URLRequest(url: th_5minUrl)
        let task = URLSession.shared.dataTask(with: request, completionHandler: {(data,response,error) -> Void in
            if let error = error {
                print(error)
                return
            }
            if let data = data {
                self.th_5mins = self.pardrJsonData(data: data)
                self.getchat()
            }
        })
        task.resume()
        //getchat()
    }
    func pardrJsonData(data: Data) -> [Th_5min]{
        var th_5mins = [Th_5min]()
        do {
            let jsonResult = try JSONSerialization.jsonObject(with: data, options: JSONSerialization.ReadingOptions.mutableContainers) as? NSDictionary
            let jsonTh_5mins = jsonResult?["TH_5min"] as! [AnyObject]
            print(jsonTh_5mins)
            print(th_5mins.count)
            for jsonTh_5min in jsonTh_5mins{
                var th_5min = Th_5min()
                th_5min.Data = jsonTh_5min["Data"] as! String
                th_5min.Time = jsonTh_5min["Time"] as! String
                th_5min.XTP_A = jsonTh_5min["XTP_A"] as! Double
                th_5min.XHP_A = jsonTh_5min["XHP_A"] as! Double
                print(th_5min)
                th_5mins.append(th_5min)
                //getchat()
            }        }catch{
                print(error)
        }
        //getchat()
        return th_5mins

    }

这就是我使用快速代码绘制折线图的方式。

@objc func getchat(){

        chartView = LineChartView()  
        chartView.frame = CGRect(x: 20, y: 80, width: self.view.bounds.width-20,height: self.view.bounds.height-100)
        self.view.addSubview(chartView)
        var dataEntries1 = [ChartDataEntry]()
        for i in 0..<th_5mins.count {
            chartView.xAxis.valueFormatter = IndexAxisValueFormatter(values: [th_5mins[i].Time])
            let y = th_5mins[i].XTP_A
            let entry = ChartDataEntry.init(x: Double(i), y: Double(y))
            dataEntries1.append(entry)
        }
        let chartDataSet1 = LineChartDataSet(entries: dataEntries1, label: "temperature")

        chartDataSet1.colors = [NSUIColor.red]

        var dataEntries2 = [ChartDataEntry]()
        for i in 0..<th_5mins.count {
            chartView.xAxis.valueFormatter = IndexAxisValueFormatter(values: [th_5mins[i].Time])
            let y = th_5mins[i].XHP_A
            let entry = ChartDataEntry.init(x: Double(i), y: Double(y))
            dataEntries2.append(entry)

        }
        let chartDataSet2 = LineChartDataSet(entries: dataEntries2, label: "humidity")
        chartDataSet2.colors = [NSUIColor.black]

        let chartData = LineChartData(dataSets: [chartDataSet1, chartDataSet2])

        chartView.data = chartData
    }
}

这是我工作的结果。

enter image description here

尽管成功显示了json数据，但我不知道为什么加载时间很长，我希望json数据中的“时间”可以显示在上方的X轴上，标有我的温度和湿度，并且无法成功。我也希望可以将折线图视图实现为布局。

Answer 1

“我不知道为什么它要长时间加载”。您是说图形在打开视图后不会立即加载吗？这是因为数据正在从远程源异步加载（现在正确，做得很好）。通过网络下载JSON可能需要花费几秒钟的时间。那没问题。您可以在浏览器中测试端点，并查看响应需要多长时间。
“我希望json数据中的'时间'可以显示在上方的X轴上”。是。您可以在循环外进行//store/index.js export const actions = { nuxtClientInit({ commit }, { req }) { const autho = localStorage.getItem('auth._token.local') //or whatever yours is called commit('SET_AUTHO', autho) console.log('From nuxtClientInit - '+autho) } }的分配，并且应将所有标签作为class MyTileView: UIView { var drawBounds = CGRect(x: 0, y: 0, width: 0, height: 0) let drawBarrierQueue = DispatchQueue(label: "com.example.app", qos: .userInteractive, // draw operations require the highest priority threading available attributes: .concurrent, target: nil) override func layoutSubviews() { drawBarrierQueue.sync(flags: .barrier) { // a barrier operation waits for active operations to finish before starting, and prevents other operations from starting until this one has finished super.layoutSubviews(); self.drawBounds = self.bounds // do other stuff that should hold up drawing } } override func draw(_ layer: CALayer, in ctx: CGContext) { drawBarrierQueue.sync { // do all of your drawing ctx.setFillColor(red: 1.0, green: 0, blue: 0, alpha: 1.0) ctx.fill(drawBounds) } } }传递到构造函数中。尝试以下代码，替换等效循环：-
```
IndexAxisValueFormatter
```

请注意，根据时间进行绘图的方法将产生均匀分布的图形，而与您的时间间隔无关（例如，如果前两个之间的读数相隔5分钟，而下两个之间的相隔5年，则它们将它们之间仍然出现均匀的缝隙。

如何使用swift

1 个答案: