NSString *loc = @"zh-Hans";
    if (![self isChinese]) {
        loc = @"en";
    }
    NSString *path = [[NSBundle mainBundle] pathForResource:_file
                                                     ofType:@"strings"                                                       
                                                inDirectory:nil
                                            forLocalization:loc];
    
    // compiled .strings file becomes a "binary property list"
    NSDictionary *dict = [NSDictionary dictionaryWithContentsOfFile:path];
    
    NSString *str = [dict objectForKey:_key];
    if (str) {
        return str;
    }
    return _key;

然後用NSNotificationCenter去實現內容更新