tweaking some basic objc snippets

extras/imported/objc-mode/Language Boilerplate/Class Method (M).yasnippet

@@ -2,9 +2,8 @@
 # key: M
 # contributor: Translated from TextMate Snippet
 # name: Class Method
-## condition: "(source.objc | source.objc++) & meta.scope.implementation.objc - meta.function-with-body"
+# condition: (and (yas/objc-implementation-p) (not (yas/objc-method-body-p)))
 # --
-+ (${1:id})${2:method}${3::(${4:id})${5:${4/(NS([AEIOQUY])?(\w+).*)|(.)?.*/(?1:a(?2:n$2)$3:(?4:anArgument))/}}}
-{$0${1/^(void|IBAction)$|(.*)/(?2:
-	return nil;)/}
-}
++ (${1:id})${2:`(or yas/selected-text "method")`}${3::(${4:id})${5:${4:$(
+yas/objc-guess-instance-name yas/text)}}} {$0${1:$(if (
+string-match yas/objc-void-regexp text) "}" "\n  return nil;\n}")}