一:通過時間戳除以每天的秒數,得到當前的天數,主要用來比較天數,用來製作不帶時分秒的Date。
NSTimeInterval interval = [[NSDate date] timeIntervalSince1970];
int daySeconds = 24 * 60 * 60;
NSInteger theDays = interval / daySeconds;
//theDays: 16658
NSDate *theDate = [NSDate dateWithTimeIntervalSince1970:allDays * daySeconds];
//theDate: 2015-08-11 00:00:00 +0000
二:可以獲得當前日期的幾乎所有日期相關
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc]init];
[dateFormatter setDateFormat:@"'公元前/後:'G '年份:'u'='yyyy'='yy '季度:'q'='qqq'='qqqq '月份:'M'='MMM'='MMMM '今天是今年第幾周:'w '今天是本月第幾周:'W '今天是今年第幾天:'D '今天是本月第幾天:'d '星期:'c'='ccc'='cccc '上午/下午:'a '小時:'h'='H '分鐘:'m '秒:'s '毫秒:'SSS '這一天已過多少毫秒:'A '時區名稱:'zzzz'='vvvv '時區編號:'Z "];
NSLog(@"%@", [dateFormatter stringFromDate:[NSDate date]]);
三:獲得當前日期的年,月,日,(時,分,秒)
NSDate *currentDate = [NSDate date];
NSCalendar* calendar = [NSCalendar currentCalendar];
NSDateComponents* components = [calendar components:NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit fromDate:currentDate];
NSInteger m = [components month]; // month
NSInteger d = [components day]; // day
NSInteger y = [components year]; // year