iphone - NSString 问题

Question

我有一个 NSString，它被分配了一个字符串值。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

路径组件的 NSString 添加可以派上用场，特别是: pathExtension和 stringByDeletingPathExtension

编辑:另请参阅:stringByAppendingPathExtension: (正如 Dave DeLong 所指出的)

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

如果你确实希望 magicFunction 存在，你可以向 NSString 添加一个类别方法，如下所示:

@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

使用方式如下:

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