首字母大写，下划线和回用Objective-C

10

Chris对RegexKitLite的建议很好。这是一个很好的工具包，但这可以通过NSScanner轻松完成。在+uppercaseLetterCharacterSet和+lowercaseLetterCharacterSet之间交替使用-scanCharactersFromSet:intoString:。返回时，您可以使用-scanUpToCharactersFromSet:来代替，只需使用一个字符集，其中只有一个下划线。

来源

2009-12-17 02:32:09

+1

感谢罗布 - 我缺乏使用NSScanner的经验，这让我忽略了这个解决方案，但它比我拥有的要干净得多。 – 2009-12-17 13:10:49

4

如果您的问题只是您的代码的可见性，那么您可以使用您设计的方法为NSString设置一个类别。那样，你只能看到一次丑陋的混乱。 ;）

例如：

@interface NSString(Conversions) { 
    - (NSString *)asCamelCase; 
    - (NSString *)asUnderscored; 
} 

@implementation NSString(Conversions) { 
    - (NSString *)asCamelCase { 
      // whatever you came up with 
    } 
    - (NSString *)asUnderscored { 
      // whatever you came up with 
    } 
}

编辑：一个快速谷歌搜索后，我找不到这样做的任何方式，即使在平原。然而，我没有找到一个框架，可能是有用的。它被称为RegexKitLite。它使用内置的ICU库，因此它只为最终的二进制文件增加了大约20K。

来源

2009-12-17 01:50:48

+1

克里斯，感谢多的RegexKitLite指针。我一定会在未来的项目中使用它！ – 2009-12-17 13:11:20

+0

它比在iOS开发条款中发布这个答案迟了约10万年;应该有其他人在这里绊倒：不要使用RegexKitLite。在发布这个答案约六个月后，iOS 4中出现了“NSRegularExpression”，将相同的ICU库引入标准框架。 – Tommy 2015-11-10 21:03:03

9

这些怎么样：

NSString *MyCamelCaseToUnderscores(NSString *input) { 
    NSMutableString *output = [NSMutableString string]; 
    NSCharacterSet *uppercase = [NSCharacterSet uppercaseLetterCharacterSet]; 
    for (NSInteger idx = 0; idx < [input length]; idx += 1) { 
     unichar c = [input characterAtIndex:idx]; 
     if ([uppercase characterIsMember:c]) { 
      [output appendFormat:@"_%@", [[NSString stringWithCharacters:&c length:1] lowercaseString]]; 
     } else { 
      [output appendFormat:@"%C", c]; 
     } 
    } 
    return output; 
} 

NSString *MyUnderscoresToCamelCase(NSString *underscores) { 
    NSMutableString *output = [NSMutableString string]; 
    BOOL makeNextCharacterUpperCase = NO; 
    for (NSInteger idx = 0; idx < [underscores length]; idx += 1) { 
     unichar c = [underscores characterAtIndex:idx]; 
     if (c == '_') { 
      makeNextCharacterUpperCase = YES; 
     } else if (makeNextCharacterUpperCase) { 
      [output appendString:[[NSString stringWithCharacters:&c length:1] uppercaseString]]; 
      makeNextCharacterUpperCase = NO; 
     } else { 
      [output appendFormat:@"%C", c]; 
     } 
    } 
    return output; 
}

有些缺点是他们使用临时字符串大小写之间转换，而他们没有缩写词的任何逻辑，所以myURL将导致my_u_r_l。

来源

2009-12-17 03:45:39

4

这是我实现罗布的回答：

@implementation NSString (CamelCaseConversion) 

// Convert a camel case string into a dased word sparated string. 
// In case of scanning error, return nil. 
// Camel case string must not start with a capital. 
- (NSString *)fromCamelCaseToDashed { 

    NSScanner *scanner = [NSScanner scannerWithString:self]; 
    scanner.caseSensitive = YES; 

    NSString *builder = [NSString string]; 
    NSString *buffer = nil; 
    NSUInteger lastScanLocation = 0; 

    while ([scanner isAtEnd] == NO) { 

     if ([scanner scanCharactersFromSet:[NSCharacterSet lowercaseLetterCharacterSet] intoString:&buffer]) { 

      builder = [builder stringByAppendingString:buffer]; 

      if ([scanner scanCharactersFromSet:[NSCharacterSet uppercaseLetterCharacterSet] intoString:&buffer]) { 

       builder = [builder stringByAppendingString:@"-"]; 
       builder = [builder stringByAppendingString:[buffer lowercaseString]]; 
      } 
     } 

     // If the scanner location has not moved, there's a problem somewhere. 
     if (lastScanLocation == scanner.scanLocation) return nil; 
     lastScanLocation = scanner.scanLocation; 
    } 

    return builder; 
} 

@end

来源

2010-11-28 21:13:02 MonsieurDart

+0

为什么不使用NSMutableString作为构建器？ – 2013-08-05 21:21:19

+0

确实会更好。 :-) – MonsieurDart 2013-08-21 09:09:21

0

我已经联合在这里找到了我的重构库，es_ios_utils答案。见NSCategories.h：

@property(nonatomic, readonly) NSString *asCamelCaseFromUnderscores; 
@property(nonatomic, readonly) NSString *asUnderscoresFromCamelCase;

用法：

@"my_string".asCamelCaseFromUnderscores

产量@ “的myString”

请把改进！

来源

2011-06-08 15:35:16

3

这是基于上述所有情况的又一个版本。该版本处理其他表单。特别是，测试了以下内容：

camelCase => camel_case 
camelCaseWord => camel_case_word 
camelURL => camel_url 
camelURLCase => camel_url_case 
CamelCase => camel_case

这里去

- (NSString *)fromCamelCaseToDashed3 { 
    NSMutableString *output = [NSMutableString string]; 
    NSCharacterSet *uppercase = [NSCharacterSet uppercaseLetterCharacterSet]; 
    BOOL previousCharacterWasUppercase = FALSE; 
    BOOL currentCharacterIsUppercase = FALSE; 
    unichar currentChar = 0; 
    unichar previousChar = 0; 
    for (NSInteger idx = 0; idx < [self length]; idx += 1) { 
     previousChar = currentChar; 
     currentChar = [self characterAtIndex:idx]; 
     previousCharacterWasUppercase = currentCharacterIsUppercase; 
     currentCharacterIsUppercase = [uppercase characterIsMember:currentChar]; 

     if (!previousCharacterWasUppercase && currentCharacterIsUppercase && idx > 0) { 
      // insert an _ between the characters 
      [output appendString:@"_"]; 
     } else if (previousCharacterWasUppercase && !currentCharacterIsUppercase) { 
      // insert an _ before the previous character 
      // insert an _ before the last character in the string 
      if ([output length] > 1) { 
       unichar charTwoBack = [output characterAtIndex:[output length]-2]; 
       if (charTwoBack != '_') { 
        [output insertString:@"_" atIndex:[output length]-1]; 
       } 
      } 
     } 
     // Append the current character lowercase 
     [output appendString:[[NSString stringWithCharacters:&currentChar length:1] lowercaseString]]; 
    } 
    return output; 
}

来源

2012-07-13 03:34:30 David

+0

'previousChar'永远不会被读取并且可以被删除。 – 2014-07-01 08:32:09

0

我偶然发现了这个问题寻找一种方式，以驼峰式转换为间隔，用户可显示的字符串。这里是我的解决方案，它的工作比@代替@ “_””“

- (NSString *)fromCamelCaseToSpaced:(NSString*)input { 
    NSCharacterSet* lower = [NSCharacterSet lowercaseLetterCharacterSet]; 
    NSCharacterSet* upper = [NSCharacterSet uppercaseLetterCharacterSet]; 

    for (int i = 1; i < input.length; i++) { 
     if ([upper characterIsMember:[input characterAtIndex:i]] && 
      [lower characterIsMember:[input characterAtIndex:i-1]]) 
     { 
      NSString* soFar = [input substringToIndex:i]; 
      NSString* left = [input substringFromIndex:i]; 
      return [NSString stringWithFormat:@"%@ %@", soFar, [self fromCamelCaseToSpaced:left]]; 
     } 
    } 
    return input; 
}

来源

2013-03-02 10:03:32

+0

看起来已经很不错了，但是：1.如果输入为空，该怎么办？ 2.如何转换回来工作？ 3.你的循环不能以'i = 1'开始，使'i> 1'过时？ – Trinimon 2013-03-02 10:44:36

+0

1.如果输入为零，则返回零，因为发送给零的长度消息将返回0 2.好的一点，我不需要这个在我的应用程序 3.我喜欢这一点，编辑它到我的答案 – 2013-03-02 11:55:27

9

试试这个神奇的更好：

NSString* camelCaseString = @"myBundleVersion"; 
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"(?<=[a-z])([A-Z])|([A-Z])(?=[a-z])" options:0 error:nil]; 
NSString *underscoreString = [[regex stringByReplacingMatchesInString:camelCaseString options:0 range:NSMakeRange(0, camelCaseString.length) withTemplate:@"_$1$2"] lowercaseString]; 
NSLog(@"%@", underscoreString);

输出：my_bundle_version

来源

2013-11-08 02:09:40 malhal

+3

如果该字符串是帕斯卡情况下，即MyBundleVersion，它会产生_my_bundle_version – 2014-08-11 06:34:13

+0

我很想看到一个固定的前导下划线和一个转换另一种方式的版本。 – 2015-08-11 17:41:28

+1

@PeterDeWeese，像[这一个]（https://regex101.com/r/zM4dD2/1）？ – 2016-02-05 13:21:01

0

OK家伙。下面是一个所有正则表达式的答案，这是我考虑的唯一正确的方法：

考虑：

NSString *MYSTRING = "foo_bar"; 

NSRegularExpression *_toCamelCase = [NSRegularExpression 
    regularExpressionWithPattern:@"(_)([a-z])" 
    options:NSRegularExpressionCaseInsensitive error:&error]; 

NSString *camelCaseAttribute = [_toCamelCase 
    stringByReplacingMatchesInString:MYSTRING options:0 
    range:NSMakeRange(0, attribute.length) 
    withTemplate:@"\\U$2"];

息率Foobar的。

相反：

NSString *MYSTRING = "fooBar"; 


NSRegularExpression *camelCaseTo_ = [NSRegularExpression 
    regularExpressionWithPattern:@"([A-Z])" 
    options:0 error:&error]; 

NSString *underscoreParsedAttribute = [camelCaseTo_ 
    stringByReplacingMatchesInString:MYSTRING 
    options:0 range:NSMakeRange(0, attribute.length) 
    withTemplate:@"_$1"]; 
underscoreParsedAttribute = [underscoreParsedAttribute lowercaseString];

产量：foo_bar这样。

\ U $ 2替换第二捕获组大写版本的本身：d

\ 1然而大号$，奇怪的是，不与自身的小写版本替换第一捕获组:(不确定为什么，它应该工作：/

来源

2016-01-05 22:15:52 CommaToast

1

如果你关心你的代码的速度，你可能要编写的代码更高性能的版本：

- (nonnull NSString *)camelCaseToSnakeCaseString { 
    if ([self length] == 0) { 
     return @""; 
    } 
    NSMutableString *output = [NSMutableString string]; 
    NSCharacterSet *digitSet = [NSCharacterSet decimalDigitCharacterSet]; 
    NSCharacterSet *uppercaseSet = [NSCharacterSet uppercaseLetterCharacterSet]; 
    NSCharacterSet *lowercaseSet = [NSCharacterSet lowercaseLetterCharacterSet]; 

    for (NSInteger idx = 0; idx < [self length]; idx += 1) { 
     unichar c = [self characterAtIndex:idx]; 

     // if it's the last one then just append lowercase of character 
     if (idx == [self length] - 1) { 
      if ([uppercaseSet characterIsMember:c]) { 
       [output appendFormat:@"%@", [[NSString stringWithCharacters:&c length:1] lowercaseString]]; 
      } 
      else { 
       [output appendFormat:@"%C", c]; 
      } 
      continue; 
     } 

     unichar nextC = [self characterAtIndex:(idx+1)]; 
     // this logic finds the boundaries between lowercase/uppercase/digits and lets the string be split accordingly. 
     if ([lowercaseSet characterIsMember:c] && [uppercaseSet characterIsMember:nextC]) { 
      [output appendFormat:@"%@_", [[NSString stringWithCharacters:&c length:1] lowercaseString]]; 
     } 
     else if ([lowercaseSet characterIsMember:c] && [digitSet characterIsMember:nextC]) { 
      [output appendFormat:@"%@_", [[NSString stringWithCharacters:&c length:1] lowercaseString]]; 
     } 
     else if ([digitSet characterIsMember:c] && [uppercaseSet characterIsMember:nextC]) { 
      [output appendFormat:@"%@_", [[NSString stringWithCharacters:&c length:1] lowercaseString]]; 
     } 
     else { 
      // Append lowercase of character 
      if ([uppercaseSet characterIsMember:c]) { 
       [output appendFormat:@"%@", [[NSString stringWithCharacters:&c length:1] lowercaseString]]; 
      } 
      else { 
       [output appendFormat:@"%C", c]; 
      } 
     } 
    } 
    return output; 
}

来源

2016-09-29 15:18:27 raulzito234

首字母大写，下划线和回用Objective-C

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