iOS 时间操作

今天整理了下iOS中时间的一些操作：

1. 获得当前时间

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

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

NSString * timeStr = [dateFormatter stringFromDate:[NSDate date]];

NSLog(@"timeStr = %@",timeStr);

2. 两个时间比较大小

NSDate *dateA = [dateFormatter dateFromString:timeStr];

NSDate *dateB = [dateFormatter dateFromString:@"2015-11-11"];

NSComparisonResult result = [dateA compare:dateB];

if (result == NSOrderedDescending)

{

//
前面的跟后面的比
大于

NSLog(@"前面的时间大于");

}

else if (result == NSOrderedAscending)

{

//
前面的跟后面的比
小于

NSLog(@"前面的时间小于");

}

else if (result == NSOrderedSame)

{

//
相等

}

3. 计算两个时间中间差几天

NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];

unsigned int unitFlags = NSDayCalendarUnit;

NSDateComponents *comps = [gregorian components:unitFlags fromDate:dateA toDate:dateB options:0];

NSLog(@"days = %ld",(long)[comps day]);