NSString问题

Question

我有一个NSString，它被赋予一个字符串值。如何获取此NSString并在文件名及其扩展名之间插入@"-thumbnail"？

换句话说，我如何从：

NSString *fileName = @"myFile.png";

至：

NSString *thumbnailName = [NSString someMagicFunction...]
NSLog(@"%@", thumbnailName);  // Should Output "myFile-thumbnail.png"

Answer 1

为路径组件添加的NSString可能会派上用场，特别是：pathExtension和stringByDeletingPathExtension

编辑：另请参阅：stringByAppendingPathExtension: (由Dave DeLong指出)

NSString * ext = [fileName pathExtension];
NSString * baseName = [fileName stringByDeletingPathExtension];
NSString * thumbBase = [baseName stringByAppendingString:@"-thumbnail"];
NSString * thumbnailName = [thumbBase stringByAppendingPathExtension:ext];

如果您确实希望magicFunction存在，您可以像这样向NSString添加一个category方法：

@interface NSString (MoreMagic)
- (NSString *)stringByAddingFileSuffix:(NSString *)suffix;
@end

@implementation NSString (MoreMagic)
- (NSString *)stringByAddingFileSuffix:(NSString *)suffix
{
    NSString * extension = [self pathExtension];
    NSString * baseName = [self stringByDeletingPathExtension];
    NSString * thumbBase = [baseName stringByAppendingString:suffix];
    return [thumbBase stringByAppendingPathExtension:extension];
}
@end

使用方法如下：

NSString * thumbnailName = [fileName stringByAddingFileSuffix:@"-thumbnail"];

Answer 2

如果您确定您的文件名，您也可以简单地执行以下操作：

[NSString stringByReplacingOccurrencesOfString:@"." withString:@"-thumbnail."]

但是路径处理的东西更干净(不管有多少“。您在名字中有)，并且对于更棘手的情况很好地了解。

Answer 3

为此，我们有一个开源类别：-[NSString ks_stringWithPathSuffix:]