Check if date or date containing string has 12h (am pm) or 24h format

[DimaZava]

I've faced a necessity of checking current device's time display settings, exactly 12/24h format.
What about having such kind of extensions both for Date and String types?

extension Date {

    var is12HourFormat: Bool {
        let dateFormatter = DateFormatter()
        let dateString = dateFormatter.string(from: self)
        return dateString.contains(dateFormatter.amSymbol) || dateString.contains(dateFormatter.pmSymbol)
    }
}

extension String {

    /// Check if string can be formatted as date and if it has 12 hour format.
    /// Returns nil if string isn't a date, and true or false if it has 12 hour format or not.
    var is12HourFormat: Bool? {
        let dateFormatter = DateFormatter()
        let date = dateFormatter.date(from: self)
        return (contains(dateFormatter.amSymbol) || contains(dateFormatter.pmSymbol)) && date != nil
    }
}

[omaralbeik]

@DimaZava Thanks for bringing this :)
The AM or PM time is coming from the DateFormatter and not from Date, if we have the same date on different devices with different Locale we will get both is12HourFormat and is12HourFormat true for the same date 🤔

[guykogus]

I think it makes more sense for this to be a Locale extension. Something like

extension Locale {
    var is12HourTimeFormat: Bool {
        let dateFormatter = DateFormatter()
        dateFormatter.timeStyle = .short
        dateFormatter.dateStyle = .none
        dateFormatter.locale = self
        let dateString = dateFormatter.string(from: Date())
        return dateString.contains(dateFormatter.amSymbol) || dateString.contains(dateFormatter.pmSymbol)
    }
}

[DimaZava]

@guykogus I think it's better idea than mine. If you don't mind I can create PR for it