NSDate *date = [NSDate date];NSLog(@"%@",date);

2016-07-01 17:31:02.410 OCString[907:402963] 2016-07-01 09:31:02 +0000    //因为时区不一样，需要格式化为本地时间
Program ended with exit code: 0

        //日前格式化NSDateFormatter *formatter = [[NSDateFormatter alloc]init];//设置日期格式化对象的两个属性formatter.dateStyle = NSDateFormatterShortStyle;formatter.timeStyle = NSDateFormatterShortStyle;NSString *result = [formatter stringFromDate:date];NSLog(@"%@",result);

2016-07-01 17:36:20.719 OCString[917:424185] 16/7/1 17:36
Program ended with exit code: 0

NSDate *date = [NSDate date];

        //获取系统提供的日历对象NSCalendar *calender = [NSCalendar currentCalendar];

        NSRange range = [calender rangeOfUnit:NSCalendarUnitDay inUnit:NSCalendarUnitMonth forDate:date];NSLog(@"%@",NSStringFromRange(range));

2016-07-01 17:46:21.526 OCString[947:466115] {1, 31}
Program ended with exit code: 0

NSDate *date = [NSDate date];

  NSCalendar *calender = [NSCalendar currentCalendar];　

NSRange range = [calender rangeOfUnit:NSCalendarUnitDay inUnit:NSCalendarUnitMonth forDate:date];

NSDateComponents *todayComp = [calender components:NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear fromDate:date];

        NSDateComponents *startComp = [todayComp copy];startComp.day = range.location;　

        NSDateComponents *endComp = [todayComp copy];endComp.day = range.length;

        NSDate *startDate = [calender dateFromComponents:startComp];NSDate *endDate = [calender dateFromComponents:endComp];

        NSInteger start_week = [calender ordinalityOfUnit:NSCalendarUnitWeekday inUnit:NSCalendarUnitWeekOfYear forDate:startDate];NSInteger end_week = [calender ordinalityOfUnit:NSCalendarUnitWeekday inUnit:NSCalendarUnitWeekOfYear forDate:endDate];