Flutter, Swift and Kotlin - Date(Time)型 同日判定

flutter

bool isSameDay(DateTime a, DateTime b) {
    return a.year == b.year && a.month == b.month && a.day == b.day;
}

swift

func isSameDay(a: Date, b: Date) -> Bool {
    return Calendar.current.isDate(a, equalTo: b, toGranularity: .day)
}

kotlin

// 文字列で比較するパターン
@SuppressLint("SimpleDateFormat")
fun isSameDay(a: Date, b: Date): Boolean {
    val sdf = SimpleDateFormat("yyyyMMdd")
    return sdf.format(a) == sdf.format(b)
}
// LocalDateに変換するパターン
fun isSameDay(a: Date, b: Date): Boolean {
    val ald = a.toInstant().atZone(ZoneId.systemDefault()).toLocalDate()
    val bld = b.toInstant().atZone(ZoneId.systemDefault()).toLocalDate()
    return ald.year == bld.year && ald.dayOfYear == bld.dayOfYear
}