时间日期
NSDate
在OC中，可以使用如下的代码创建一个UTC的时间：
NSDate *currentUTCDate = [NSDate date]
但在Swift中，使用 let date = NSDate()
获取到的则是本地时间。
UTC时间与本地化时间
let date = NSDate();
// "Apr 1, 2015, 8:53 AM" <-- local without seconds
var formatter = NSDateFormatter();
formatter.dateFormat = "yyyy-MM-dd HH:mm:ss ZZZ";
let defaultTimeZoneStr = formatter.stringFromDate(date);
// "2015-04-01 08:52:00 -0400" <-- same date, local, but with seconds
formatter.timeZone = NSTimeZone(abbreviation: "UTC");
let utcTimeZoneStr = formatter.stringFromDate(date);
// "2015-04-01 12:52:00 +0000" <-- same date, now in UTC
时间比较
如果需要比较两个日期，可以使用如下方法，在如下代码中已经展示了如何处理不同的返回结果：
// Date comparision to compare current date and end date.
var dateComparisionResult:NSComparisonResult = NSDate().compare(endDate)
if dateComparisionResult == NSComparisonResult.OrderedAscending
{
// Current date is smaller than end date.
}
else if dateComparisionResult == NSComparisonResult.OrderedDescending
{
// Current date is greater than end date.
}
else if dateComparisionResult == NSComparisonResult.OrderedSame
{
// Current date and end date are same.
}
TimeStamp
如果需要将某个TimeStamp("/Date(1427909016000-0800)”)转化为NSDate对象，那么可以使用如下的扩展工具，该扩展将会把TimeStamp转化为本地化时间。其中1427909016000表示从Unix计时以来的毫秒数，而-0800表示时区：
/// Swift3的写法
extension NSDate {
convenience init?(jsonDate: String) {
let prefix = "/Date("
let suffix = ")/"
let scanner = Scanner(string: jsonDate)
// Check prefix:
if scanner.scanString(prefix, into: nil) {
// Read milliseconds part:
var milliseconds : Int64 = 0
if scanner.scanInt64(&milliseconds) {
// Milliseconds to seconds:
var timeStamp = TimeInterval(milliseconds)/1000.0
// Read optional timezone part:
var timeZoneOffset : Int = 0
if scanner.scanInt(&timeZoneOffset) {
let hours = timeZoneOffset / 100
let minutes = timeZoneOffset % 100
// Adjust timestamp according to timezone:
timeStamp += TimeInterval(3600 * hours + 60 * minutes)
}
// Check suffix:
if scanner.scanString(suffix, into: nil) {
// Success! Create NSDate and return.
self.init(timeIntervalSince1970: timeStamp)
return
}
}
}
// Wrong format, return nil. (The compiler requires us to
// do an initialization first.)
self.init(timeIntervalSince1970: 0)
return nil
}
}
使用的例子如下：
if let theDate = NSDate(jsonDate: "/Date(1427909016000-0800)/") {
println(theDate)
} else {
print("错误的格式")
}
NSDateFormatter：格式化时间
var dataString = "April 1, 2015" as String
var dateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "MM-dd-yyyy"
dateFormatter.timeZone = NSTimeZone.localTimeZone()
// convert string into date
let dateValue = dateFormatter.dateFromString(dataString) as NSDate!
print(dateValue)
NSCalendar 日历
// Setup the calendar object
let calendar = NSCalendar.currentCalendar()
// Set up date object
let date = NSDate()
// Create an NSDate for the first and last day of the month
//let components = calendar.components(NSCalendarUnit.CalendarUnitYear |
// NSCalendarUnit.CalendarUnitMonth |
// NSCalendarUnit.WeekdayCalendarUnit |
// NSCalendarUnit.WeekCalendarUnit |
// NSCalendarUnit.CalendarUnitDay,
// fromDate: date)
// Create an NSDate for the first and last day of the month
let components = NSCalendar.currentCalendar().components(NSCalendarUnit.CalendarUnitMonth, fromDate: date)
components.month
// Getting the First and Last date of the month
components.day = 1
let firstDateOfMonth: NSDate = calendar.dateFromComponents(components)!
components.month += 1
components.day = 0
let lastDateOfMonth: NSDate = calendar.dateFromComponents(components)!
var unitFlags = NSCalendarUnit.WeekOfMonthCalendarUnit |
NSCalendarUnit.WeekdayCalendarUnit |
NSCalendarUnit.CalendarUnitDay
let firstDateComponents = calendar.components(unitFlags, fromDate: firstDateOfMonth)
let lastDateComponents = calendar.components(unitFlags, fromDate: lastDateOfMonth)
// Sun = 1, Sat = 7
let firstWeek = firstDateComponents.weekOfMonth
let lastWeek = lastDateComponents.weekOfMonth
let numOfDatesToPrepend = firstDateComponents.weekday - 1
let numOfDatesToAppend = 7 - lastDateComponents.weekday + (6 - lastDateComponents.weekOfMonth) * 7
let startDate: NSDate = calendar.dateByAddingUnit(NSCalendarUnit.CalendarUnitDay, value: -numOfDatesToPrepend, toDate: firstDateOfMonth, options: nil)!
let endDate: NSDate = calendar.dateByAddingUnit(NSCalendarUnit.CalendarUnitDay, value: numOfDatesToAppend, toDate: lastDateOfMonth, options: nil)!
Array(map(0..<42) {
calendar.dateByAddingUnit(NSCalendarUnit.CalendarUnitDay, value: $0, toDate: startDate, options: nil)!
})
"\(components.year)"
var dateString = "2014-10-3" // change to your date format
var dateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "YYYY-MM-dd"
var someDate = dateFormatter.dateFromString(dateString)
print(someDate)
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