Hey,
I used SunKit and MoonKit in my upcoming application. I like them and it's great that the classes are still alive and that you keep improving them.

In practical implementation, I've encountered difficulties when working with time zones and would have a tip for an improvement that would greatly simplify their use.

My difficulties:
When I want to use a Sun class for a time zone other than the current time zone, I have to work very carefully with the time zone.
For example: the facility is located in Prague and I need the position of the sun during the day in Cupertino.

• Before initializing, I need to calculate the time zone offset in Cupertino and pass it to the Sun class as a Double
• pre-shift each date set via setDate() to the Cupertino time zone
• in addition, I have to recalculate and set setTimeZone() before setDate() because the previous date could have a different DST

This is not a safe and convenient solution.

That's why I propose to initialize the Sun class with the TimeZone class.
The Sun class can then do all the necessary conversions for time zones by itself:

• calculate the time zone offset itself
• adjust the time passed via setDate by itself
• calculate the DST itself

Michal Kus

Hello,

I have downloaded SunKit and installed in via the Swift Package Manager in Xcode.

I want to show in a view (example the ContentView) for example the sunrise time.

Is it possible to provide me the code to do this. As I am relatively new to SwiftUI (You have to start somewhere I guess), I am a little bit lost 'in the moment' :)

Is it possible to help me and show me how I can show these time in a Xcode View?

Your help would be appreciated.

WIth the introduction of the new way to handle timezones backwards compatibility may be compromised.
Implement a way to guarantee backwards compatibility.

If you delete private in getDateFrom, it will be possible to calculate the time for any elevation, e.g. nautical twilight (-12°).

Hello,

thank you for your awesome work.

As the sun moves from sunrise to sunset in a given location you provide the azimuth of the sun on sunrise and sunset.
I have a question: is it possible to have the data of the current position of the sun. For example if it is 10h30 to see the position of the sun on the map between sunrise and sunset, and if the time evolves you see the sun on a map moving?

is this possible?

It would be practical if Sun and Moon had a common ancestor that had properties that both classes have the same (date, altitude, rise, set ....).

Right now I have two almost identical methods, although one would be enough.

Thanks, Michal Kůs

I tested how the package works after plugging in TimeZone. Unfortunately, I found a bug in working with daylight saving time.
Example: sunrise in Los Angeles
March 11: calculates 07:08, (this is an error, should be 06:08)
March 12th is the end of daylight saving time
March 13: calculates 07:06 (this is correct)

This error is not in the MoonKit package.

func testSun() throws {
    //https://gml.noaa.gov/grad/solcalc/sunrise.html
    //https://www.timeanddate.com/sun/usa/los-angeles?month=3&year=2023
    
    guard let pst = TimeZone(abbreviation: "PST") else {
        abort()
    }
    
    guard let utc = TimeZone(abbreviation: "UTC") else {
        abort()
    }
    
    let location: CLLocation = .init(latitude: 34.052235, longitude: -118.243683)

    let sun = Sun.init(location: location, timeZone: pst)
    
    sun.setDate(SunKit.createDateCustomTimeZone(day: 11, month: 3, year: 2023, hour: 22, minute: 00, seconds: 00, timeZone: pst))
    XCTAssertEqual(sun.sunrise.toString(pst), "03/11, 06:08") //XCTAssertEqual failed: ("03/11, 07:08") is not equal to ("03/11, 06:08")
    XCTAssertEqual(sun.sunset.toString(pst), "03/11, 17:58")  //XCTAssertEqual failed: ("03/11, 18:58") is not equal to ("03/11, 17:58")
    XCTAssertEqual(sun.sunrise.toString(utc), "03/11, 14:08") //XCTAssertEqual failed: ("03/11, 15:08") is not equal to ("03/11, 14:08")
    XCTAssertEqual(sun.sunset.toString(utc), "03/12, 01:58")  //XCTAssertEqual failed: ("03/12, 02:58") is not equal to ("03/12, 01:58")

    sun.setDate(SunKit.createDateCustomTimeZone(day: 13, month: 3, year: 2023, hour: 22, minute: 00, seconds: 00, timeZone: pst))
    XCTAssertEqual(sun.sunrise.toString(pst), "03/13, 07:06")
    XCTAssertEqual(sun.sunset.toString(pst), "03/13, 18:59")
    XCTAssertEqual(sun.sunrise.toString(utc), "03/13, 14:06")
    XCTAssertEqual(sun.sunset.toString(utc), "03/14, 01:59")
}




extension Date {

func toString(_ timeZone: TimeZone) -> String {
    let df = DateFormatter()
    df.timeZone = timeZone
    let custom = DateFormatter.dateFormat(fromTemplate: "MMdd HH:mm",
                                          options: 0,
                                          locale: Locale(identifier: "en"))
    df.dateFormat = custom
    return df.string(from: self)
}

}

extension TimeZone {

func offset(_ date: Date) -> Double {
    let res =
        Int(self.secondsFromGMT(for: date))
        + Int(self.daylightSavingTimeOffset(for: date))
        - Int(Calendar.current.timeZone.secondsFromGMT(for: date))
        - Int(Calendar.current.timeZone.daylightSavingTimeOffset(for: date))
    print("\(date.toString())  \(Int(self.secondsFromGMT(for: date)/3600)), \(Int(self.daylightSavingTimeOffset(for: date)/3600)), \(Int(Calendar.current.timeZone.secondsFromGMT(for: date)/3600)), \(Int(Calendar.current.timeZone.daylightSavingTimeOffset(for: date)/3600))")
    return Double(res)/3600.0
    
}

}

Hello I am a little bit confused.
I want to see the sunset time of tomorrow. I am a little bit stuck with the date.
How can I modify tthe code to retrieve the sunset time of tomorrow?

When setting a date any day before 1AM, solar midnight time points to the previous day. This leads to wrong timings in specific situations, with up to 36 hours of distance between the current solar noon and midnight timings.

Based on the issue opened on MoonKit, SunKit need to be updated with the same fix.
For more info -> Sunlitt/MoonKit#1

When testing SunKit, the dumpDateInfos function includes the following:

Civil dusk          -> Tuesday, May 2, 2023 at 5:31:09 AM Mountain Daylight Time
Civil Dawn           -> Tuesday, May 2, 2023 at 8:21:42 PM Mountain Daylight Time
Nautical Dusk     -> Tuesday, May 2, 2023 at 4:56:05 AM Mountain Daylight Time
Nautical Dawn      -> Tuesday, May 2, 2023 at 8:56:46 PM Mountain Daylight Time
Astronomical Dusk -> Tuesday, May 2, 2023 at 4:18:26 AM Mountain Daylight Time
Astronomical Dawn  -> Tuesday, May 2, 2023 at 9:34:25 PM Mountain Daylight Time

In each case, dawn is shown as being in the evening, while dusk is in the morning.

I thought at first that the dawn times were for tomorrow, i.e. the next time dawn arrived, but they all show the same date. Printing their UTC values shows the same issue, dusk occurs before dawn:

Civil dawn: 2023-05-03 02:21:42 +0000
Civil dusk: 2023-05-02 11:31:09 +0000

Nautical dawn: 2023-05-03 02:56:46 +0000
Nautical dusk: 2023-05-02 10:56:05 +0000

Astronomical dawn: 2023-05-03 03:34:25 +0000
Astronomical dusk: 2023-05-02 10:18:26 +0000

I don’t know if this means dawn and dusk times are reversed or if there’s some other problem.

My Package.resolved shows that I’m using tag 2.6.3, so I should be up to date.