iOS ユニークなファイル名をつける

「hoge_file.txt」というファイル名が既にあった場合は「hoge_file-2.txt」になります。

呼び出し側

NSString *uniqueFileName = [HogeUtil getUniqueFileNameInDocumentDirectory:@"hoge_file" type:@"txt"];

HogeUtil.m

+ (NSString*)getUniqueFileNameInDocumentDirectory:(NSString*)_name type:(NSString*)_type {

    NSArray *filePaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
                                                             NSUserDomainMask,YES);
    NSString *documentDirectory = [filePaths objectAtIndex:0];

    NSString* fileName = [NSString stringWithFormat:@"%@.%@", _name, _type];

    NSString *filePath = [documentDirectory stringByAppendingPathComponent:fileName];

    int i = 1;

    while ([[NSFileManager defaultManager] fileExistsAtPath:filePath]) {
        ++i;
        filePath = [NSString stringWithFormat:@"%@/%@-%d.%@", documentDirectory, _name, i, _type];
        fileName = [NSString stringWithFormat:@"%@-%d.%@", _name, i, _type];
    }

    return fileName;
}