NSString独特的文件路径，以避免名称冲突

Question

是否有一种简单的方法来获取给定的文件路径并修改它以避免名称冲突？喜欢的东西：

[StringUtils stringToAvoidNameCollisionForPath:path]; 

，对于类型的给定路径：/foo/bar/file.png，将返回/foo/bar/file-1.png后来人们都会增加“-1”类似于什么Safari浏览器也对下载的文件。

UPDATE：

我跟着灰沟的建议和我贴我的实现作为答案:)

Answer 1

我决定实施我自己的解决方案，我想分享我的代码。这不是最可取的实施，但似乎做的工作：

+ (NSString *)stringToAvoidNameCollisionForPath:(NSString *)path { 

    // raise an exception for invalid paths 
    if (path == nil || [path length] == 0) { 
     [NSException raise:@"DMStringUtilsException" format:@"Invalid path"]; 
    } 

    NSFileManager *manager = [[[NSFileManager alloc] init] autorelease]; 
    BOOL isDirectory; 

    // file does not exist, so the path doesn't need to change 
    if (![manager fileExistsAtPath:path isDirectory:&isDirectory]) { 
     return path; 
    } 

    NSString *lastComponent = [path lastPathComponent]; 
    NSString *fileName = isDirectory ? lastComponent : [lastComponent stringByDeletingPathExtension]; 
    NSString *ext = isDirectory ? @"" : [NSString stringWithFormat:@".%@", [path pathExtension]]; 
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"-([0-9]{1,})$" options:0 error:nil]; 
    NSArray *matches = [regex matchesInString:fileName options:0 range:STRING_RANGE(fileName)]; 

    // missing suffix... start from 1 (foo-1.ext) 
    if ([matches count] == 0) { 
     return [NSString stringWithFormat:@"%@-1%@", fileName, ext]; 
    } 

    // get last match (theoretically the only one due to "$" in the regex) 
    NSTextCheckingResult *result = (NSTextCheckingResult *)[matches lastObject]; 

    // extract suffix value 
    NSUInteger counterValue = [[fileName substringWithRange:[result rangeAtIndex:1]] integerValue]; 

    // remove old suffix from the string 
    NSString *fileNameNoSuffix = [fileName stringByReplacingCharactersInRange:[result rangeAtIndex:0] withString:@""]; 

    // return the path with the incremented counter suffix 
    return [NSString stringWithFormat:@"%@-%i%@", fileNameNoSuffix, counterValue + 1, ext]; 
} 

......而下面是我使用的测试：

- (void)testStringToAvoidNameCollisionForPath { 

    NSBundle *bundle = [NSBundle bundleForClass:[self class]]; 

    // bad configs // 

    STAssertThrows([DMStringUtils stringToAvoidNameCollisionForPath:nil], nil); 
    STAssertThrows([DMStringUtils stringToAvoidNameCollisionForPath:@""], nil); 

    // files // 

    NSString *path = [bundle pathForResource:@"bar-0.abc" ofType:@"txt"]; 
    NSString *savePath = [DMStringUtils stringToAvoidNameCollisionForPath:path]; 
    STAssertEqualObjects([savePath lastPathComponent], @"bar-0.abc-1.txt", nil); 

    NSString *path1 = [bundle pathForResource:@"bar1" ofType:@"txt"]; 
    NSString *savePath1 = [DMStringUtils stringToAvoidNameCollisionForPath:path1]; 
    STAssertEqualObjects([savePath1 lastPathComponent], @"bar1-1.txt", nil); 

    NSString *path2 = [bundle pathForResource:@"bar51.foo.yeah1" ofType:@"txt"]; 
    NSString *savePath2 = [DMStringUtils stringToAvoidNameCollisionForPath:path2]; 
    STAssertEqualObjects([savePath2 lastPathComponent], @"bar51.foo.yeah1-1.txt", nil); 

    NSString *path3 = [path1 stringByDeletingLastPathComponent]; 
    NSString *savePath3 = [DMStringUtils stringToAvoidNameCollisionForPath:[path3 stringByAppendingPathComponent:@"xxx.zip"]]; 
    STAssertEqualObjects([savePath3 lastPathComponent], @"xxx.zip", nil); 

    NSString *path4 = [bundle pathForResource:@"foo.bar1-1-2-3-4" ofType:@"txt"]; 
    NSString *savePath4 = [DMStringUtils stringToAvoidNameCollisionForPath:path4]; 
    STAssertEqualObjects([savePath4 lastPathComponent], @"foo.bar1-1-2-3-5.txt", nil); 

    NSString *path5 = [bundle pathForResource:@"bar1-1" ofType:@"txt"]; 
    NSString *savePath5 = [DMStringUtils stringToAvoidNameCollisionForPath:path5]; 
    STAssertEqualObjects([savePath5 lastPathComponent], @"bar1-2.txt", nil); 

    // folders // 

    NSString *path6 = [DOCUMENTS_PATH stringByAppendingPathComponent:@"foo1"]; 
    NSString *savePath6 = [DMStringUtils stringToAvoidNameCollisionForPath:path6]; 
    STAssertEqualObjects([savePath6 lastPathComponent], @"foo1-1", nil); 

    NSString *path7 = [DOCUMENTS_PATH stringByAppendingPathComponent:@"bar1-1"]; 
    NSString *savePath7 = [DMStringUtils stringToAvoidNameCollisionForPath:path7]; 
    STAssertEqualObjects([savePath7 lastPathComponent], @"bar1-2", nil); 

    NSString *path8 = [DOCUMENTS_PATH stringByAppendingPathComponent:@"foo-5.bar123"]; 
    NSString *savePath8 = [DMStringUtils stringToAvoidNameCollisionForPath:path8]; 
    STAssertEqualObjects([savePath8 lastPathComponent], @"foo-5.bar123-1", nil); 

} 

Answer 2

我也有类似的问题，并用稍宽的方法上来，试图命名文件iTunes会采用同样的方式（当你设置为管理你的音乐库，并且你有多个同名的音轨等）

它工作在一个循环中，所以这个函数可以多次调用并且仍然产生有效的输出。解释参数，fileName是没有路径或扩展名（例如“文件”）的文件的名称，folder只是路径（例如“/ foo/bar”），而fileType只是扩展名（例如“png”） 。这三个可以作为一个字符串传递并在之后分开，但在我的情况下，将它们分开是有意义的。

currentPath（它可以是空的，但不为零）在重命名文件而不是创建新文件时非常有用。例如，如果您尝试重命名为“/foo/bar/file.png”的“/ foo/bar/file 1.png”，则会传入“/ foo/bar/file 1.png “对于currentPath，如果”/foo/bar/file.png“已经存在，你将回到你开始的路径，而不是看到”/ foo/bar/file 1.png“并返回”/ foo/bar/file 2.png“

+ (NSString *)uniqueFile:(NSString *)fileName 
       inFolder:(NSString *)folder 
      withExtension:(NSString *)fileType 
     mayDuplicatePath:(NSString *)currentPath 
{ 
    NSUInteger existingCount = 0; 
    NSString *result; 
    NSFileManager *manager = [NSFileManager defaultManager]; 

    do { 
     NSString *format = existingCount > 0 ? @"%@ %lu" : @"%@"; 

     fileName = [NSString stringWithFormat:format, fileName, existingCount++]; 
     result = [fileName stringByAppendingFormat:@".%@", [fileType lowercaseString]]; 

     result = [folder stringByAppendingPathComponent:result]; 
    } while ([manager fileExistsAtPath:result] && 
      // This comparison must be case insensitive, as the file system is most likely so 
      [result caseInsensitiveCompare:currentPath] != NSOrderedSame); 

    return result; 
}