如何将Swift enum：String转换为Objective-C枚举：NSString？

我有一个问题将此快速枚举转换为Objective-C：

public enum ISO8601Format: String { case Year = "yyyy" // 1997 case YearMonth = "yyyy-MM" // 1997-07 case Date = "yyyy-MM-dd" // 1997-07-16 case DateTime = "yyyy-MM-dd'T'HH:mmZ" // 1997-07-16T19:20+01:00 case DateTimeSec = "yyyy-MM-dd'T'HH:mm:ssZ" // 1997-07-16T19:20:30+01:00 case DateTimeMilliSec = "yyyy-MM-dd'T'HH:mm:ss.SSSZ" // 1997-07-16T19:20:30.45+01:00 init(dateString:String) { switch dateString.characters.count { case 4: self = ISO8601Format(rawValue: ISO8601Format.Year.rawValue)! case 7: self = ISO8601Format(rawValue: ISO8601Format.YearMonth.rawValue)! case 10: self = ISO8601Format(rawValue: ISO8601Format.Date.rawValue)! case 22: self = ISO8601Format(rawValue: ISO8601Format.DateTime.rawValue)! case 25: self = ISO8601Format(rawValue: ISO8601Format.DateTimeSec.rawValue)! default:// 28: self = ISO8601Format(rawValue: ISO8601Format.DateTimeMilliSec.rawValue)! } } } public enum DateFormat { case ISO8601(ISO8601Format?), DotNet, RSS, AltRSS, Custom(String) } 

我已经研究过这个地方，发现这个和这个：

枚举NSString的最佳方法

枚举值为NSString（iOS）

不太明白这些答案。我正在寻找更现代的Objective-C语法更优雅的解决scheme（如果有的话）或更好地解释这些答案。

谢谢 ！

Answer 1

 NSString * const ISO8601DateFormatType = @"ISO8601"; NSString * const DotNetDateFormatType = @"DotNet"; NSString * const RSSDateFormatType = @"RSS"; NSString * const AltRSSDateFormatType = @"AltRSS"; NSString * const CustomDateFormatType = @"Custom"; NSString * const ISOFormatYear = @"yyyy"; NSString * const ISOFormatYearMonth = @"yyyy-MM"; // 1997-07 NSString * const ISOFormatDate = @"yyyy-MM-dd"; // 1997-07-16 NSString * const ISOFormatDateTime = @"yyyy-MM-dd'T'HH:mmZ"; // 1997-07-16T19:20+01:00 NSString * const ISOFormatDateTimeSec = @"yyyy-MM-dd'T'HH:mm:ssZ"; // 1997-07-16T19:20:30+01:00 NSString * const ISOFormatDateTimeMilliSec = @"yyyy-MM-dd'T'HH:mm:ss.SSSZ"; // 1997-07-16T19:20:30.45+01:00 @interface DateFormat : NSObject + (instancetype) ISODateFormat: (NSString *) isoFormat; + (instancetype) DotNetDateFormat; + (instancetype) RSSDateFormat; + (instancetype) AltRSSDateFormat; + (instancetype) CustomDateFormat: (NSString *) formatString; @property (readonly) NSString *dateFormatType; @property (readonly) NSString *formatDetails; @end @implementation DateFormat - (instancetype) initWithType: (NSString *) formatType details: (NSString *) details { if(self = [super init]) { _dateFormatType = formatType; _formatDetails = details; } return self; } + (instancetype) ISODateFormat: (NSString *) isoFormat { return [[DateFormat alloc] initWithType: ISO8601DateFormatType details: isoFormat]; } + (instancetype) DotNetDateFormat { return [[DateFormat alloc] initWithType: DotNetDateFormatType details: nil]; } + (instancetype) RSSDateFormat { return [[DateFormat alloc] initWithType: RSSDateFormatType details: nil]; } + (instancetype) AltRSSDateFormat { return [[DateFormat alloc] initWithType: AltRSSDateFormatType details: nil]; } + (instancetype) CustomDateFormat: (NSString *) formatString { return [[DateFormat alloc] initWithType: CustomDateFormatType details: formatString]; } @end