从NSCalendar获得一个月的第一天

Question

我有一个方法的子集,需要获得当月的第一天.

NSDate *today = [NSDate date];  // returns correctly 28 february 2013
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *components = [[NSDateComponents alloc] init];
components.day = 1;
NSDate *dayOneInCurrentMonth = [gregorian dateByAddingComponents:components toDate:today options:0];

dayOneInCurrentMonth然后打印出来2013-03-01 09:53:49 +0000,下个月的第一天.

我如何获得当月的第一天？

Answer 1

你的逻辑是错误的:你没有将日期设置为1,而是在当前日期添加一天.

尝试类似的东西:

NSDate *today = [NSDate date];
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];

NSDateComponents *components = [gregorian components:(NSEraCalendarUnit | NSYearCalendarUnit | NSMonthCalendarUnit) fromDate:today];
components.day = 1;

NSDate *dayOneInCurrentMonth = [gregorian dateFromComponents:components];