ios - NSDateFormatter を使用した NSString から NSDate への変換は null を返します

Question

NSString を NSDate に変換しようとすると、dateFromString から null が返されます。コードは次のとおりです。

    NSString *dateString = @"Wed 16 Oct 2013";
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setLocale:[NSLocale systemLocale]];
    [dateFormatter setTimeZone:[NSTimeZone systemTimeZone]];
    [dateFormatter setDateFormat:@"EEE dd MMM yyyy"];
    [dateFormatter setFormatterBehavior:NSDateFormatterBehaviorDefault];
    NSDate *myDate = [dateFormatter dateFromString: dateString];

これについて何か提案があれば教えてください。

Answer 1

It's a locale issue and it's sort of the same of NSDateFormatter Strings in iOS 7, just the other way around.

Probably in your system locale Wed or/and Oct are not valid valid literals for a weekday or/and a month.

Try setting the locale to en_US or to currentLocale

NSLocale *locale = [[NSLocale alloc] initWithLocaleIdentifier:@"en_US"];

or

NSLocale *locale = [NSLocale currentLocale];

Answer 2

フォーマット スタイルの詳細については、http://cybersam.com/ios-dev/quick-guide-to-ios-dateformatting

NSString *dateString = @"Wed 16 Oct 2013";
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
// this is imporant - we set our input date format to match our input string
// if format doesn't match you'll get nil from your string, so be careful
[dateFormatter setDateFormat:@"EEE dd MMM yyy"];
NSDate *dateFromString = [[NSDate alloc] init];
dateFromString = [dateFormatter dateFromString:dateString];
NSLog(@"%@", dateFromString);