Question

我正在计算两个NSDates之间的时间差，它总是返回0.0000。我使用相同的逻辑来计算时间戳并且格式正确。当我尝试单独记录日期时，它会被正确打印当我打印差异时，它打印0.0000 ...这里是计算日期的代码..

-(NSDate *) toLocalTime
{
NSTimeZone *tz = [NSTimeZone defaultTimeZone];
NSInteger seconds = [tz secondsFromGMTForDate: [NSDate date]];
return [NSDate dateWithTimeInterval: seconds sinceDate: [NSDate date]];
}

这里是我发现差异的代码..

NSLog(@"the time when the location was updated is %@",timeWhenTheLocationWasUpdated);
NSLog(@"the time when the server was contacted last time was %@",timeWhenLastLocationPosted);

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"dd-MM-yyyy HH:mm:ss ZZZ"];
NSDate *timeofUpdatingLocation = [[NSDate alloc] init];
NSDate *timeofPostingToTheServer = [[NSDate alloc]init];
timeofUpdatingLocation = [dateFormatter dateFromString:timeWhenTheLocationWasUpdated];
timeofPostingToTheServer = [dateFormatter dateFromString:timeWhenLastLocationPosted];
NSTimeInterval difference = [timeofPostingToTheServer timeIntervalSinceDate:timeofUpdatingLocation];
NSLog(@"the difference between posting the location to the server and updating the location is %f",difference);

代码开头的两个NSlog都以日期格式化程序中提到的格式正确打印日期。

Answer 1

在Objective-C中，向nil对象发送消息是完全合法的。你回来0 /零/假。

如果字符串与格式不匹配，则

$one = $two = 0; // empty variables foreach($Seq as $key => $value) { foreach ($value as $val) { if ($val == 1) { $one++; }else { $two++; } } } echo "total number of one's ". $one ."<br>"; echo "total number of two's ". $two ."<br>";个对象从NSdateFormatter的调用返回nil。

我的猜测是，您对dateFromString的调用失败且dateFromString为零，因此您将返回0。

（作为一个脚注，正如rmaddy在他的评论中所暗示的那样，对于你正试图解决的问题，本地时间似乎没有意义）

两个日期之间的时间间隔返回nil

1 个答案: