从特定年份的给定月份获取每一天

Question

是否可以从日历组件（Swift 3）中获取给定月份和年份的每一天的日期数组

目前我只是找到一种方法来计算天数，仅此而已。

目的是开发我的自定义日历，但我被困在这个阶段......

我正在尝试编写的扩展将如下所示：

extension Date 
{
    func getAllDays() -> [Date]
}

或者类似的方法：

func getAllDays(month: Int, year: Int) -> [Date]

Answer 1

终于找到了办法：

extension Date
{    
    mutating func addDays(n: Int)
    {
        let cal = Calendar.current
        self = cal.date(byAdding: .day, value: n, to: self)!
    }

    func firstDayOfTheMonth() -> Date {
        return Calendar.current.date(from:
            Calendar.current.dateComponents([.year,.month], from: self))!
    }

    func getAllDays() -> [Date]
    {
        var days = [Date]()

        let calendar = Calendar.current

        let range = calendar.range(of: .day, in: .month, for: self)!

        var day = firstDayOfTheMonth()

        for _ in 1...range.count
        {
            days.append(day)
            day.addDays(n: 1)
        }

        return days
    }
}

使用示例：

let allDays = Date().getAllDays()

输出：

2017-06-01 22:00:00 +0000

2017-06-02 22:00:00 +0000

2017-06-03 22:00:00 +0000

2017-06-04 22:00:00 +0000

...

...

2017-06-30 22:00:00 +0000

Answer 2

这里有更好的代码来做同样的事情

extension Date {

    var startOfMonth: Date {
            return Calendar.iso8601.date(from: Calendar.iso8601.dateComponents([.year, .month], from: self))!
        }

    var daysOfMonth: [Date] {
        let startOfMonth = self.startOfMonth
        let calendar = Calendar.current
        let range = calendar.range(of: .day, in: .month, for: self)!
        return range.compactMap{ calendar.date(byAdding: .day, value: $0, to: startOfMonth)}
    }
}


extension Calendar {
    static let iso8601 = Calendar(identifier: .iso8601)
}