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iOS Build a Simple iPhone App (iOS7) Refactoring into a Model Readonly Attribute

filibertoheiras
filibertoheiras
3,211 Points
Posted by filibertoheiras
filibertoheiras
3,211 Points

#import vs @class

Hi, when creating our classes and import and import them in our ViewController why and when to use #import "myClass.h" or @class myClass, seem to have the same functionality.

In this lesson we used both on .h use @class but on .m used #import.

Thanks for your time!

3 Answers

Stone Preston
Stone Preston
42,016 Points
Stone Preston
Stone Preston
42,016 Points

you generally use @class in .h files (using @class just lets the compiler know that that class EXISTS, but it doesnt know anything ABOUT it like its methods, properties, etc), then use #imports in .m files which will let the compiler know all the methods and properties that class has in its header file.

you can use #import in both .h and .m , and with a small number of #imports thats fine, however with a lot of them it can slow down the compiler

so if your file just needs to know a class name and nothing about that class (methods properties etc) then you can use @class, if it needs to know its methods and properties you need to import it

However in all the iOS courses ive rarely seen @class used, #import is used almost exclusively as the time saved is minimal in most cases.

filibertoheiras
filibertoheiras
3,211 Points
filibertoheiras
filibertoheiras
3,211 Points

Ok, so the point of that is CPU and Memory consuming.. I got it, thanks!!

Stone Preston
Stone Preston
42,016 Points
Stone Preston
Stone Preston
42,016 Points

yeah since using import will import that classes header file, as well as any header files the class being imported imports, and so on and so on so it can add up to a lot of imports.