iOS开发：NSDate

1:根据输入的时间的到星期几（2017-2-22）－（星期三）

-(NSString *)getTheDayOfTheWeekByDateString:(NSString *)dateString{

NSDateFormatter *inputFormatter=[[NSDateFormatter alloc]init];

[inputFormatter setDateFormat:@"yyyy-MM-dd"];

NSDate *formatterDate=[inputFormatter dateFromString:dateString];

NSDateFormatter *outputFormatter=[[NSDateFormatter alloc]init];

outputFormatter.locale = [[NSLocale alloc]initWithLocaleIdentifier:@"zh"];//中文（星期三）

//    outputFormatter.locale = [[NSLocale alloc]initWithLocaleIdentifier:@"en_US"];//默认：英文（Wednesday）

[outputFormatter setDateFormat:@"EEEE-MMMM-d"];

NSString *outputDateStr=[outputFormatter stringFromDate:formatterDate];

NSArray *weekArray=[outputDateStr componentsSeparatedByString:@"-"];

return [weekArray objectAtIndex:0];

}

NSLog(@"今天是－ %@", [self getTheDayOfTheWeekByDateString:@"2017-2-22"]);

输出：今天是－星期三。

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2判断时间

//根据字符串的到一个时间-->调用判断时间方法。

NSDateFormatter *fmt = [[NSDateFormatter alloc] init];

fmt.dateFormat = @"yyyy-MM-dd";

NSDate  *dd = [fmt dateFromString:@"2016-2-22"];

NSLog(@"%d",[dd isThisYear]);

/** 比较from和self的时间差值*/

- (NSDateComponents *)deltaFrom:(NSDate *)from {

NSCalendar *calendar = [NSCalendar currentCalendar];// 日历

// 比较时间

NSCalendarUnit unit = NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond;

return [calendar components:unit fromDate:from toDate:self options:0];

}

/**是否为今年*/

- (BOOL)isThisYear {

NSCalendar *calendar = [NSCalendar currentCalendar];// 日历

NSInteger nowYear = [calendar component:NSCalendarUnitYear fromDate:[NSDate date]];

NSInteger selfYear = [calendar component:NSCalendarUnitYear fromDate:self];

return nowYear == selfYear;

}

/**是否为今天*/

- (BOOL)isToday {

NSDateFormatter *fmt = [[NSDateFormatter alloc] init];

fmt.dateFormat = @"yyyy-MM-dd";

NSString *nowString = [fmt stringFromDate:[NSDate date]];

NSString *selfString = [fmt stringFromDate:self];

return [nowString isEqualToString:selfString];

}

/**是否为昨天*/

- (BOOL)isYesterday {

// 2016-12-31 23:59:59 -> 2016-12-31

// 2017-01-01 00:00:01 -> 2017-01-01

// 日期格式化类

NSDateFormatter *fmt = [[NSDateFormatter alloc] init];

fmt.dateFormat = @"yyyy-MM-dd";

NSDate *nowDate = [fmt dateFromString:[fmt stringFromDate:[NSDate date]]];

NSDate *selfDate = [fmt dateFromString:[fmt stringFromDate:self]];

NSCalendar *calendar = [NSCalendar currentCalendar];

NSDateComponents *cmps = [calendar components:NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear fromDate:selfDate toDate:nowDate options:0];

return cmps.year == 0

&& cmps.month == 0

&& cmps.day == 1;

}

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常用的时间格式有iOS NSDateFormatter日期时间格式处理的用法

yyyy-MM-dd HH:mm:ss.SSS

yyyy-MM-dd HH:mm:ss

yyyy-MM-dd

MM dd yyyy

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待补充：

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