One thing that irks me is that the author doesn't stick to ObjC naming conventions.
Take for example the capitalize methods. In ruby, you have "capitalize" and "capitalize!" to distinguish the immutable and mutable versions. To make this distinction in ObjC, you generally use nouns vs. verbs. So for the equivalent of ruby's "capitalize", you'd use "capitalizedString" (which is in fact provided by NSString). But the mutable version, the equivalent of ruby's "capitalize" should simply be "capitalize", not "capitalizedStringInPlace".
Take for example the capitalize methods. In ruby, you have "capitalize" and "capitalize!" to distinguish the immutable and mutable versions. To make this distinction in ObjC, you generally use nouns vs. verbs. So for the equivalent of ruby's "capitalize", you'd use "capitalizedString" (which is in fact provided by NSString). But the mutable version, the equivalent of ruby's "capitalize" should simply be "capitalize", not "capitalizedStringInPlace".