更改24小时后，dateFromString返回nil [英] dateFromString return nil after change 24 hour

问题描述

NSDateFormatter *timeFormat = [[NSDateFormatter alloc] init];
[timeFormat setDateFormat:@"hh:mm a"];

NSDate* sourceDate = [timeFormat dateFromString:@"19/11/2010 12:00 am"];
if(sourceDate==nil)
{
    NSLog(@"source date nil");
}

我在iPhone中使用24小时设置。更改为24小时设置后，datefromstring始终返回nil。我改为12小时格式，它再次运行。为什么？

I'm using 24 hour setting in iPhone. After I change to 24 hour setting, datefromstring always return nil. I rechange to 12 hour format, it's working again. Why ?

推荐答案

需要设置区域设置以避免受到24小时设置更改的影响。

格式还必须匹配输入字符串（在您的示例中包含日期）：

The locale needs to be set to avoid being affected by the 24-hour setting change.
The format also has to match the input string (which in your example includes the date):

NSDateFormatter *timeFormat = [[NSDateFormatter alloc] init];
NSLocale *locale = [[[NSLocale alloc] 
                    initWithLocaleIdentifier:@"en_US_POSIX"] autorelease];  
[timeFormat setLocale:locale];
[timeFormat setDateFormat:@"dd/MM/yyyy hh:mm a"];

NSDate* sourceDate = [timeFormat dateFromString:@"19/11/2010 12:00 am"];
if(sourceDate==nil)
{
    NSLog(@"source date nil");
}

参见 QA1480 了解更多信息。

这篇关于更改24小时后，dateFromString返回nil的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！