#import using angle brackets < > and quote marks " "

user_128875 0
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I'm wondering what decides whether you're allowed to use <Header.h> or "Header.h" when you're importing files in Objective-C. So far my observation has been that you use the quote marks "" for files in your project that you've got the implementation source to, and angle brackets <> when you're referencing a library or framework.

But how exactly does that work? What would I have to do to get my own classes to use the brackets? Right now Xcode will not allow me to do that for my own headers.

Also, by looking in some frameworks headers, I see that the headers reference each other with <frameworkname/file.h>. How does that work? It looks a lot like packages in Java, but as far as I know, there is no such thing as a package in Objective-C.

import objective-c syntax package
9 Answers

Objective-C has this in common with C/C++; the quoted form is for "local" includes of files (you need to specify the relative path from the current file, e.g. #include "headers/my_header.h"), while the angle-bracket form is for "global" includes -- those found somewhere on the include path passed to the compiler (e.g. #include <math.h>).

So to have your own headers use < > not " " you need to pass either the relative or the absolute path for your header directory to the compiler. See "How to add a global include path for Xcode" for info on how to do that in Xcode.

See this MSDN page for more info.

Mark_Pim_388830

In C, the convention is that header files in <> bracket are searched in 'system' directories and "" in user or local directories.

The definition of system and local is a bit vague, I guess. I believe it looks in system directories in include path or in CPPFLAGS for <header.h>, and local directory or directory specified with -I to compiler are searched for "header.h" files.

I assume it works similarly for Objective-C.

user_456540

To import your own classes using "< >" you have to put the header files (*.h) in the lib folder of compiler or set a SYSTEM VARIABLES ponting to your lib folder.

user_1288290

<Name.h> - Angle brackets tells to preprocessor to search in a special pre-designated system's directories. For example you import systems headers like <UIKit/UIKit.h> or added frameworks

"Name.h" - Quotation marks tells to preprocessor to search in a current directory. If a header was not found the preprocessor try to use <Name.h>. Usually you should use it with your project's files

user_47708770

With angle brackets e.g. <Foundation/Foundation.h> you import system files.

You use double quotes "Person.h" to import local files (files that you created) and to tell the compiler where to look for them.

user_57010650

If this is an Xcode project and you want to include it in a framework, have the header file you want to included open. Then, open Xcode's rightmost tab and under "Target Membership", click on the framework you want your file to available from.

e.g. If your framework is AlphaTools and your header, AceHeader, then you'll select AlphaTools on Target Membership so you can access < AlphaTools/AceHeader.h

user_63694640
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