NSDATE在一个月的第一天
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03-10-2019 - |
题
这是一个非常简单的概念,但是到目前为止,我一直找不到优雅(和日历区域独立)解决方案。我需要找到本月的第一天进行任意 NSDate
. 。例如,给定任意 NSDate
(arbitraryDate
)将返回另一个NSDATE对象(让我们打电话给 firstDayOfMonthDate
)代表一个月的第一天 arbitraryDate
. 。时间组件无关紧要,因为我只需要一个月的第一天的NSDATE对象(尽管整洁,如果时间刚好零,这将很有用)。
事先感谢您的任何帮助。
解决方案
一个可能的解决方案:
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDate *arbitraryDate = [NSDate date];
NSDateComponents *comp = [gregorian components:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit) fromDate:arbitraryDate];
[comp setDay:1];
NSDate *firstDayOfMonthDate = [gregorian dateFromComponents:comp];
其他提示
NSDateComponents *components = [[NSCalendar currentCalendar] components:NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear
fromDate:[NSDate date]];
components.day = 1;
NSDate *firstDayOfMonthDate = [[NSCalendar currentCalendar] dateFromComponents: components];
NSLog(@"First day of month: %@", [firstDayOfMonthDate descriptionWithLocale:[NSLocale currentLocale]]);
Swift 3
我包括在一个月的最后一天,以防万一对任何人都有用。
extension Date {
func lastDayOfMonth() -> Date {
let calendar = Calendar.current
let dayRange = calendar.range(of: .day, in: .month, for: self)
let dayCount = dayRange!.count
var comp = calendar.dateComponents([.year, .month, .day], from: self)
comp.day = dayCount
return calendar.date(from: comp)!
}
func firstDayOfMonth() -> Date {
let calendar: Calendar = Calendar.current
var components: DateComponents = calendar.dateComponents([.year, .month, .day], from: self)
components.setValue(1, for: .day)
return calendar.date(from: components)!
}
}
Swift版本
let arbitraryDate:NSDate = NSDate()
let calendar:NSCalendar = NSCalendar.currentCalendar()
let components:NSDateComponents = calendar.components([.Year, .Month, .Day], fromDate: arbitraryDate)
components.setValue(1, forComponent: .Day)
let firstDayOfMonthDate = calendar.dateFromComponents(components)
Swift 3:
let calendar = Calendar.current
var comps = calendar.dateComponents([.year, .month], from: date)
comps.setValue(1, for: .day)
let firstDayOfMonth = calendar.date(from: comps)!
// I tried this, but it doesn't work, why?
// let firstDayOfMonth = calendar.date(bySetting: .day, value: 1, of: date)!
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