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

Question

我在将这个快速枚举转换为Objective-C时遇到问题：

 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)
}

我已经到处研究了这个，发现了这个：

枚举NSString的最佳方法

将值枚举为NSString（iOS）

我对这些答案不太了解，我正在寻找更优雅的解决方案（如果有的话）或使用现代Objective-C语法对这些答案进行更好的解释。

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