在NSMutableDictionary中设置NSStrings“containing_underscore_characters”时会用引号括起来吗？

Question

我正在将NSStrings添加到NSMutableDictionary中。有些字符串包含下划线，有些则不包含：

NSMutableDictionary *testDict = [[NSMutableDictionary alloc] init];
[testDict setObject:@"_startWithUnderscore" forKey:@"firstKey"];
[testDict setObject:@"NoUnderscore" forKey:@"secondKey"];
[testDict setObject:@"underscores_in_middle" forKey:@"thirdKey"];
NSLog(@"%@", testDict);`

输出：

firstKey = "_startWithUnderscore"; //注意添加的引号！

secondKey = NoUnderscore; //没有引号。

thirdKey = "underscores_in_middle"; //也会获得引号。

呃，这里发生了什么？引号来自哪里？

Answer 1

if ([[testDict objectForKey:@"firstKey"] substringWithRange:NSMakeRange(0, 1)] isEqualToString:@"_"])
{
    NSLog(@"I guess the quotes are just things that NSLog prints, definitely not actually in the NSString.");
}

Answer 2

它只是NSLog的一个特征。