Dark Mode: Primary Labels

[jjatie]

Added system dark mode support for primary label colors in the frameworkMoved Color to its own Platform file

Issue Link 🔗

#4133
#3742

Goals ⚽

Introduce dark mode for label and gracefully degrade to black for the older operating systems

Implementation Details 🚧

Introduced NSUIColor.label to match modern (UI/App)Kit semantic colors for earlier versions of the respective OSes.

Testing Details 🔍

N/A

[jjatie]

@liuxuan30 Let me know if there are any issues.

[jjatie]

#3766
#4171

[liuxuan30]

@jjatie I searched NSUIColor.black and shows below, I assume you already checked?

There is some colors like
@objc open var borderColor = NSUIColor.black

                attrString = NSMutableAttributedString(string: newValue!)
                attrString?.setAttributes([
                    .foregroundColor: NSUIColor.black,
                    .font: NSUIFont.systemFont(ofSize: 12.0),
                    .paragraphStyle: paragraphStyle
                    ], range: NSMakeRange(0, attrString!.length))

    /// the color drawing borders around the bars.
    open var barBorderColor = NSUIColor.black

open class BarChartDataSet: BarLineScatterCandleBubbleChartDataSet, IBarChartDataSet
{
    private func initialize()
    {
        self.highlightColor = NSUIColor.black

do you think we should also change them?

For the border+highlight colors, I think it may be user's duty to do it, so we should leave it there;
but for the attributed string, I think it's ours?

[codecov-io]

Codecov Report

Merging #4175 into master will increase coverage by <.01%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master    #4175      +/-   ##
==========================================
+ Coverage   41.47%   41.48%   +<.01%     
==========================================
  Files         119      120       +1     
  Lines       14034    14035       +1     
==========================================
+ Hits         5821     5822       +1     
  Misses       8213     8213

Impacted Files	Coverage Δ
Source/Charts/Components/ChartLimitLine.swift	0% <ø> (ø)	⬆️
Source/Charts/Components/AxisBase.swift	64.48% <ø> (ø)	⬆️
Source/Charts/Charts/ChartViewBase.swift	30.22% <ø> (ø)	⬆️
Source/Charts/Utils/Platform.swift	13.33% <ø> (ø)	⬆️
Source/Charts/Components/Description.swift	100% <ø> (ø)	⬆️
Source/Charts/Components/Legend.swift	65.09% <ø> (ø)	⬆️
Source/Charts/Utils/Platform+Color.swift	100% <100%> (ø)
...Charts/Data/Implementations/ChartBaseDataSet.swift	25.82% <50%> (ø)	⬆️

---

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[jjatie]

@jjatie I searched NSUIColor.black and shows below, I assume you already checked?

There is some colors like
@objc open var borderColor = NSUIColor.black

                attrString = NSMutableAttributedString(string: newValue!)
                attrString?.setAttributes([
                    .foregroundColor: NSUIColor.black,
                    .font: NSUIFont.systemFont(ofSize: 12.0),
                    .paragraphStyle: paragraphStyle
                    ], range: NSMakeRange(0, attrString!.length))

    /// the color drawing borders around the bars.
    open var barBorderColor = NSUIColor.black

open class BarChartDataSet: BarLineScatterCandleBubbleChartDataSet, IBarChartDataSet
{
    private func initialize()
    {
        self.highlightColor = NSUIColor.black

do you think we should also change them?

For the border+highlight colors, I think it may be user's duty to do it, so we should leave it there;
but for the attributed string, I think it's ours?

I think it's unclear whether or not we should change border and highlight colors, and users have a way to change it themselves. If we decided we should, we can do it in a later PR. Perhaps a separate Color.border and Color.highlight semantic color extensions.

I think you might have an older copy checked out, because I only found one text element I missed.

[liuxuan30]

let's ignore line color and border colors.
seems @available(tvOS, introduced: 9.0, obsoleted: 13.0) is not working as expected, always return .black color on iOS 13 simulators

[liuxuan30]

API not working

[liuxuan30]

reply from Apple

Apple
Nov 7, 2019 at 8:58 AM
Thanks for your report. `obsoleted` is not designed to work the way you want it to work here—it’s supposed to indicate that the symbol may have been removed by iOS 13, but it will still be used if it’s there. We don’t currently have a “polyfill” feature like the one you’re looking for, but a Swift Evolution pitch adding one might be well-received.

Given the language we have today, the original `labelOrBlack` approach discussed in the PR is probably the cleanest solution. If you’re dead-set on using the name “label”, my best idea is to redeclare the property in an Objective-C category and use the Objective-C runtime from a +load method to conditionally install the implementation if it’s not already present.