Comment by Prashant Tukadiya (JIRA)

I have checked further and found that `boundingRect` is method of extension NSString. and if i change extension String to extension NSString i can access it without self. Any one can help me to figure it out. it is swift bug or I am doing something wrong ?

Hm. There's an old feature that members of NSString are accessible on String through member access syntax, but I think it's not a recommended feature at this point anyway. It's better to explicitly convert to NSString using as. Still, though, it is confusing that using self is different from not.

cc @DougGregor, @rudkx

Comment by Prashant Tukadiya (JIRA)

@belkadan Sorry I didn't get it that why I need to use self. I understand that if property / method of String it would be easily accessed without self, as it is NSString extension it is not directly accessible without self.
I think use of self that bridges Swift's String and NSString extension.

The code in the compiler that says "NSString's members show up on String values" is specifically looking for member syntax, i.e. "foo.bar"—or in this case, "self.bar". It probably shouldn't have been written that way, but it was.

I think we'd still recommend being explicit here, even if it's ugly: (self as NSString).boundingRect(…) or let nsSelf = self as NSString; nsSelf.boundingRect(…).