从操场开始。我正在尝试创建一个简单的应用程序。
我创建了一个date对象，就像这样:
var date = NSDate()
我怎样才能得到当前的时间?在其他语言中，我可以这样做:
var hour = date.hour
但我找不到任何这样的属性/方法。我找到了一个方法，dateWithCalendarFormat。我应该用这个吗?如果是，怎么做?
当前回答
在Swift 3中，
let date = Date()
let calendar = Calendar.current()
let hour = calendar.component(.hour, from: date)
其他回答
Swift 3更新:
let date = Date()
let calendar = Calendar.current
let hour = calendar.component(.hour, from: date)
let minutes = calendar.component(.minute, from: date)
我是这样做的:
let date = NSDate()
let calendar = NSCalendar.currentCalendar()
let components = calendar.components(.CalendarUnitHour | .CalendarUnitMinute, fromDate: date)
let hour = components.hour
let minutes = components.minute
在objective-c中看到同样的问题，我如何从NSDate中获得小时和分钟?
和Nate的答案相比，你得到的是数字，而不是字符串……
你可以用swift 4或5像bellow
let date = Date()
let df = DateFormatter()
df.dateFormat = "yyyy-MM-dd HH:mm:ss"
let dateString = df.string(from: date)
输出将像波纹管
2019-12-20 09:40:08
迅速回答:
let date = NSDate()
let calendar = NSCalendar.currentCalendar()
let components = calendar.components([.Hour, .Minute], fromDate: date)
let hour = components.hour
let minutes = components.minute
你也可以使用NSDateFormatter的方便方法，例如:
func printTimestamp() {
let timestamp = NSDateFormatter.localizedStringFromDate(NSDate(), dateStyle: .MediumStyle, timeStyle: .ShortStyle)
print(timestamp)
}
printTimestamp() // Prints "Sep 9, 2014, 4:30 AM"
Swift让创建和使用扩展变得非常容易。我创建了一个sharedCode.swift文件，并在其中放入枚举、扩展名和其他有趣的东西。我创建了一个NSDate扩展来添加一些典型的功能，这是费力和丑陋的输入一遍又一遍:
extension NSDate
{
func hour() -> Int
{
//Get Hour
let calendar = NSCalendar.currentCalendar()
let components = calendar.components(.Hour, fromDate: self)
let hour = components.hour
//Return Hour
return hour
}
func minute() -> Int
{
//Get Minute
let calendar = NSCalendar.currentCalendar()
let components = calendar.components(.Minute, fromDate: self)
let minute = components.minute
//Return Minute
return minute
}
func toShortTimeString() -> String
{
//Get Short Time String
let formatter = NSDateFormatter()
formatter.timeStyle = .ShortStyle
let timeString = formatter.stringFromDate(self)
//Return Short Time String
return timeString
}
}
使用这个扩展，你现在可以做一些事情，如:
//Get Current Date
let currentDate = NSDate()
//Test Extensions in Log
NSLog("(Current Hour = \(currentDate.hour())) (Current Minute = \(currentDate.minute())) (Current Short Time String = \(currentDate.toShortTimeString()))")
在上午11:51会写出来:
(当前小时= 11)(当前分钟= 51)(当前短时间字符串= 11:51 AM)
