本月的第一天和最后一天迅速

本月的第一天和最后一天迅速

您只需使用以下命令即可获得每月的第一天

let components = calendar.components([.Year, .Month], fromDate: date)let startOfMonth = calendar.dateFromComponents(components)!print(dateFormatter.stringFromDate(startOfMonth)) // 2015-11-01

要获得该月的最后一天，请添加一个月并减去一天：

let comps2 = NSDateComponents()comps2.month = 1comps2.day = -1let endOfMonth = calendar.dateByAddingComponents(comps2, toDate: startOfMonth, options: [])!print(dateFormatter.stringFromDate(endOfMonth)) // 2015-11-30

或者，使用

rangeOfUnit

为您提供开始时间和月份长度的方法：

var startOfMonth : NSDate?var lengthOfMonth : NSTimeInterval = 0calendar.rangeOfUnit(.Month, startDate: &startOfMonth, interval: &lengthOfMonth, forDate: date)

对于月份的最后一天的日期，请加上月份的长度减去一秒：

let endOfMonth = startOfMonth!.dateByAddingTimeInterval(lengthOfMonth - 1)

为Swift5更新：

extension Date {    var startOfDay: Date {        return Calendar.current.startOfDay(for: self)    }    var startOfMonth: Date {        let calendar = Calendar(identifier: .gregorian)        let components = calendar.dateComponents([.year, .month], from: self)        return  calendar.date(from: components)!    }    var endOfDay: Date {        var components = DateComponents()        components.day = 1        components.second = -1        return Calendar.current.date(byAdding: components, to: startOfDay)!    }    var endOfMonth: Date {        var components = DateComponents()        components.month = 1        components.second = -1        return Calendar(identifier: .gregorian).date(byAdding: components, to: startOfMonth)!    }    func isMonday() -> Bool {        let calendar = Calendar(identifier: .gregorian)        let components = calendar.dateComponents([.weekday], from: self)        return components.weekday == 2    }}