我怎么能得到一个NSDate对象的年/月/日，没有其他信息?我意识到我可以用类似这样的东西来做这件事:
NSCalendar *cal = [[NSCalendar alloc] init];
NSDateComponents *components = [cal components:0 fromDate:date];
int year = [components year];
int month = [components month];
int day = [components day];
但是对于像获取NSDate的年/月/日这样简单的事情来说，这似乎是一大堆麻烦。还有其他解决办法吗?
当前回答
试试下面的方法:
NSString *birthday = @"06/15/1977";
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"MM/dd/yyyy"];
NSDate *date = [formatter dateFromString:birthday];
if(date!=nil) {
NSInteger age = [date timeIntervalSinceNow]/31556926;
NSDateComponents *components = [[NSCalendar currentCalendar] components:NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear fromDate:date];
NSInteger day = [components day];
NSInteger month = [components month];
NSInteger year = [components year];
NSLog(@"Day:%d Month:%d Year:%d Age:%d",day,month,year,age);
}
[formatter release];
其他回答
只是重新描述一下Itai的优秀(并且工作!)代码，下面是一个示例助手类，它返回给定NSDate变量的年份值。
如您所见，修改这段代码以获得月或日是很容易的。
+(int)getYear:(NSDate*)date
{
NSDateComponents *components = [[NSCalendar currentCalendar] components:NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit fromDate:date];
int year = [components year];
int month = [components month];
int day = [components day];
return year;
}
(我真不敢相信，在2013年，我们还得自己编写这样的基本iOS日期函数……)
还有一件事:永远不要使用<和>来比较两个NSDate值。
XCode很乐意接受这样的代码(没有任何错误或警告)，但其结果是一个彩票。你必须使用"compare"函数来比较nsdate:
if ([date1 compare:date2] == NSOrderedDescending) {
// date1 is greater than date2
}
在Swift 2.0中:
let date = NSDate()
let calendar = NSCalendar(identifier: NSCalendarIdentifierGregorian)!
let components = calendar.components([.Month, .Day], fromDate: date)
let (month, day) = (components.month, components.day)
斯威夫特
更简单的方法获得date的任何元素作为可选String。
extension Date {
// Year
var currentYear: String? {
return getDateComponent(dateFormat: "yy")
//return getDateComponent(dateFormat: "yyyy")
}
// Month
var currentMonth: String? {
return getDateComponent(dateFormat: "M")
//return getDateComponent(dateFormat: "MM")
//return getDateComponent(dateFormat: "MMM")
//return getDateComponent(dateFormat: "MMMM")
}
// Day
var currentDay: String? {
return getDateComponent(dateFormat: "dd")
//return getDateComponent(dateFormat: "d")
}
func getDateComponent(dateFormat: String) -> String? {
let format = DateFormatter()
format.dateFormat = dateFormat
return format.string(from: self)
}
}
let today = Date()
print("Current Year - \(today.currentYear)") // result Current Year - Optional("2017")
print("Current Month - \(today.currentMonth)") // result Current Month - Optional("7")
print("Current Day - \(today.currentDay)") // result Current Day - Optional("10")
你可以使用NSDateFormatter获取NSDate的独立组件:
NSDateFormatter *df = [[NSDateFormatter alloc] init];
[df setDateFormat:@"dd"];
myDayString = [df stringFromDate:[NSDate date]];
[df setDateFormat:@"MMM"];
myMonthString = [df stringFromDate:[NSDate date]];
[df setDateFormat:@"yy"];
myYearString = [df stringFromDate:[NSDate date]];
如果你想要得到月份的数字而不是缩写，请使用“MM”。如果你想获取整数，使用[myDayString intValue];
试试下面的方法:
NSString *birthday = @"06/15/1977";
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"MM/dd/yyyy"];
NSDate *date = [formatter dateFromString:birthday];
if(date!=nil) {
NSInteger age = [date timeIntervalSinceNow]/31556926;
NSDateComponents *components = [[NSCalendar currentCalendar] components:NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear fromDate:date];
NSInteger day = [components day];
NSInteger month = [components month];
NSInteger year = [components year];
NSLog(@"Day:%d Month:%d Year:%d Age:%d",day,month,year,age);
}
[formatter release];
