Hi!
I'm building an app that uses Swift Charts to visualize stock market data, and I'm encountering a couple of issues.
The stock API I’m using provides data only for the trading days when the market is open. The problem is that I need to skip over the missing dates (non-trading days) in the chart, but still keep the x-axis formatted correctly (e.g., group ticks by month). If I convert the dates to String to handle missing data, I lose the correct x-axis formatting, and the date labels become inaccurate among with its data.
Here’s som of the code I’m using for parsing the dates and structuring the data:
struct StockDataPoint: Identifiable, Decodable {
var id: String { datetime }
let datetime: String
let close: String
var date: Date {
datetime.toDate() ?? Date()
}
var closePrice: Double {
Double(close) ?? 0.0
}
}
extension String {
func toDate() -> Date? {
let formatter = DateFormatter()
formatter.locale = Locale(identifier: "en_US_POSIX")
formatter.timeZone = TimeZone(abbreviation: "UTC")
formatter.dateFormat = self.count == 10 ? "yyyy-MM-dd" : "yyyy-MM-dd HH:mm:ss"
return formatter.date(from: self)
}
}
And:
LineMark(
x: .value("Datum", point.date),
y: .value("Pris", point.closePrice)
)
.interpolationMethod(.cardinal)
.lineStyle(StrokeStyle(lineWidth: 0.7))
.foregroundStyle(.linearGradient(colors: [.blue, .yellow, .orange], startPoint: .bottomTrailing, endPoint: .topLeading))
.frame(height: 300)
.background(Color.black.opacity(0.6))
.chartYScale(
domain: (
(stockAPI.stockData.map { $0.closePrice }.min() ?? 0) * 0.98
...
(stockAPI.stockData.map { $0.closePrice }.max() ?? 100) * 1.02
)
)
.chartXAxis {
AxisMarks(values: .automatic(desiredCount: 5)) { value in
AxisGridLine().foregroundStyle(Color.gray.opacity(0.5))
AxisTick().foregroundStyle(Color.gray)
AxisValueLabel().foregroundStyle(Color.gray)
}
}
.chartYAxis {
AxisMarks(values: .automatic(desiredCount: 5)) { value in
AxisGridLine().foregroundStyle(Color.gray.opacity(0.5))
AxisTick().foregroundStyle(Color.gray)
AxisValueLabel().foregroundStyle(Color.gray)
}
}
What I need help with:
Skipping missing dates on the x-axis and show correct data for corresponding days.
Keeping the x-axis well formatted (grouped by month, accurate labels).
Thanks in advance for any suggestions!
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