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
我知道有很多答案，但我认为我的答案对许多人来说可能更方便
extension String {
init(epoch: Double) {
let date = Date(timeIntervalSince1970: epoch)
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "dd/MM/yyyy HH:mm:ssZZZ"
self = dateFormatter.string(from: date)
}
}
其他回答
我知道有很多答案，但我认为我的答案对许多人来说可能更方便
extension String {
init(epoch: Double) {
let date = Date(timeIntervalSince1970: epoch)
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "dd/MM/yyyy HH:mm:ssZZZ"
self = dateFormatter.string(from: date)
}
}
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)
在Swift 3中，
let date = Date()
let calendar = Calendar.current()
let hour = calendar.component(.hour, from: date)
扩展noiiv的史诗般的简洁解决方案，这里是更简洁的Swift 3/4实现:
斯威夫特3/4
let components = Calendar.current.dateComponents([.hour, .minute], from: Date())
let (hour, minute) = (components.hour, components.minute)
同时，扩展Leo Dabus的扩展，我们可以有:
extension Date {
func components(_ components: Set<Calendar.Component>) -> DateComponents {
return Calendar.current.dateComponents(components, from: self)
}
func component(_ component: Calendar.Component) -> Int {
return Calendar.current.component(component, from: self)
}
var era: Int { return component(.era) }
var year: Int { return component(.year) }
var month: Int { return component(.month) }
var day: Int { return component(.day) }
var hour: Int { return component(.hour) }
var minute: Int { return component(.minute) }
var second: Int { return component(.second) }
var weekday: Int { return component(.weekday) }
var weekdayOrdinal: Int { return component(.weekdayOrdinal) }
var quarter: Int { return component(.quarter) }
var weekOfMonth: Int { return component(.weekOfMonth) }
var weekOfYear: Int { return component(.weekOfYear) }
var yearForWeekOfYear: Int { return component(.yearForWeekOfYear) }
var nanosecond: Int { return component(.nanosecond) }
var calendar: Calendar? { return components([.calendar]).calendar }
var timeZone: TimeZone? { return components([.timeZone]).timeZone }
}
像这样使用它:
let date = Date()
let (hour, minute) = (date.hour, date.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"
