iPhone如何确定是否设置了12小时或24小时的时间显示？ [英] How can I determine if iPhone is set for 12 hour or 24 hour time display?

问题描述

我以为我最近看到了很多东西在回答这个问题，但现在我找不到了。以下是我现在使用的代码来确定24小时时间显示的设置。它适用于我在美国，但我不知道它是否会在所有地区工作。这是否足够或有更好的方法来找出目前的设置？

I thought I saw something answering this on SO recently but now I can't find it. Here is the code I am using now to determine if settings are for 24 hour time display. It works for me in the US, but I don't know if it will work in all locales. Is this sufficient or is there a better way to find out the current setting for this?

+(BOOL) use24HourClock
{
    BOOL using24HourClock = NO;

    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];    
    [dateFormatter setLocale: [NSLocale currentLocale]];    
    [dateFormatter setDateStyle:kCFDateFormatterNoStyle];
    [dateFormatter setTimeStyle:kCFDateFormatterShortStyle];    
    // get date/time (1Jan2001 0000UTC)
    NSDate* midnight = [[NSDate alloc] initWithTimeIntervalSinceReferenceDate:0];   
    NSString* dateString = [dateFormatter stringFromDate: midnight];
    // dateString will either be "15:00" or "16:00" (depending on DST) or
    // it will be "4:00 PM" or "3:00 PM" (depending on DST)
    using24HourClock = ([dateString length] == 5);
    [midnight release];
    [dateFormatter release];    

    return using24HourClock;
}

推荐答案

这是最好的方法它：

NSString *formatStringForHours = [NSDateFormatter dateFormatFromTemplate:@"j" options:0 locale:[NSLocale currentLocale]];

NSRange containsA = [formatStringForHours rangeOfString:@"a"];
BOOL hasAMPM = containsA.location != NSNotFound;

in Swift：

let formatString: NSString = NSDateFormatter.dateFormatFromTemplate("j", options: 0, locale: NSLocale.currentLocale())!
let hasAMPM = formatString.containsString("a")

这使用一个特殊的日期模板字符串叫做j。根据 ICU规格，j...

This uses a special date template string called "j". According to the ICU Spec, "j"...

请求用于区域设置（h，H，K或k）的首选小时格式，由h，H，K或k是否以标准短时间格式使用区域设置在这种API的实现中，在开始与可用格式数据的匹配之前，'j'必须由h，H，K或k代替。请注意，传递给API的框架中使用'j'是让框架请求具有语言环境首选时间周期类型（12小时或24小时）的唯一方法。

requests the preferred hour format for the locale (h, H, K, or k), as determined by whether h, H, K, or k is used in the standard short time format for the locale. In the implementation of such an API, 'j' must be replaced by h, H, K, or k before beginning a match against availableFormats data. Note that use of 'j' in a skeleton passed to an API is the only way to have a skeleton request a locale's preferred time cycle type (12-hour or 24-hour).

最后一句很重要。它是使框架请求语言环境首选时间周期类型的唯一方法。由于 NSDateFormatter 和 NSCalendar 建立在ICU库中，同样适用于此。

That last sentence is important. It "is the only way to have a skeleton request a locale's preferred time cycle type". Since NSDateFormatter and NSCalendar are built on the ICU library, the same holds true here.

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