Extension (Extension) usage in objective-C, private in objective-C

Class extension is like an "anonymous" category. The method declared in the extension is implemented in the @ Implementation of the class and its corresponding @ end.

Class sometimes needs to make the method visible to itself, we can define the classPrivate Method.

Let's take a look at the extended writing method. Note that all of the followingCodeAre defined in the. M file, but also pay attention to the brackets

# Import "person. H" @ interface person ()-(void) privatefuc; @ end @ implementation person-(void) privatefuc {}@ end

Let's compare the Writing Method of the category.

. H file

# Import <Foundation/Foundation. h> @ interface nsstring (mycompare)-(void) test; @ end

In the. M file

# Import "nsstring + mycompare. H" @ implementation nsstring (mycompare)-(void) test {}@ end