where is the right place to define contants in an Xcode project?
Such as an URL, that wont change or some images for a different backgroundstyle.
AppDelegate.h? If so, where exactly? I'd like to create clean code.
Thanks
What about you create a header file, probably constants.h and define your constants in it, for example
#define URL_WEBSERVICE #"http://..."
#define COLOR_TEXT [UIColor colorWithRed:.75 green:1.0 blue:.4 alpha:1.0]
#define MAX_RESULTS 100
You can also import this header file into your precompiled header file .pch so that the values in it become visible to all your files.
Related
Hope all of you'll be fine.
I am doing a project in which i need to add core-data functionality. I am working on xcode-5. I need to add pch file in xcode-5 existing project as it was missing in the project. I have searched a lot on net to add pch file in xcode-5 but only found procedures to add pch file in xcode-6. which is totally different with xocde-5. Please provide step by step help to add pch file in xcode 5 (as I am new to ios). Many thanks in advance.
Here is how you can set the prefix header, it has to be done in the target's build settings:
In Xcode and in your open project, select the project-icon in the upper left corner so you can see the PROJECT and the TARGETS.
Select the target where you want to add the prefix header file. On the right side, select Build Settings. In the search field on the right side, type prefix header to reveal the setting Prefix Header quickly
(and at the left side of the search field, select ALL).
The path to put here is either an absolute path or a path relative to the Xcode project-file.
Here an example of a prefix header file that I use to share the DSLog macro:
// Zero-Prefix.pch
#ifdef __OBJC__
#import <Cocoa/Cocoa.h>
#endif
#ifdef DEBUG
# define DSLog(fmt, ...) NSLog((#"%s [Line %d] " fmt), __PRETTY_FUNCTION__, __LINE__, ##__VA_ARGS__);
#else
# define DSLog(...)
#endif
Can I put #define MY_VAR 1 in a file and #define MY_VAR 2 in a different file without any problem?
In other words, is #define a local or a global definition?
The answer depends on what kind of file you are talking about:
If it is a header file, then your #define-d constant is visible in all files including the header
If it is a .c/.m/.mm./.cpp file, then #defined constant is limited in scope to the file where it is defined.
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.
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.
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.
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.
#import <> vs ""
<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
Just stumbled upon the same problem, there are 2 types of search paths is Xcode:
User Header Search Paths
Header Search Paths
If you add your own include folders into Header Search Paths, you can use angled brackets without any problem.
Or set Always Search User Path to YES so you can use angle brackets.
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.
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
WHAT IS HEADER FILE ?
Header files contain definitions of functions and variables which can be incorporated into any C program by using the pre-processor #include statement. Standard header files are provided with each compiler, and cover a range of areas, string handling, mathematical, data conversion, printing and reading of variables.
Ex- #include it contain the information about input like scanf(),and out put like printf() function and etc in a compiler.
INCLUDE
1) #INCLUDE:-
It is a pre-processor that process before process of main function.
The main work of pre-processor is to initialize the environment of program i.e that is the program with the header file.
2).h:-
(Header file) A header file is a file with extension .h which contains C function declarations and macro definitions and to be shared between several source files.
Q) There are two types of header files: the files that the programmer writes and the files that come with your compiler ?
A)In a angular brackets
Angular-bracket form is for "global" includes -- those found somewhere on the include path passed to the compiler (e.g. #include)
It is used for using of library function which is all ready define in compiler.
In C the convention is that header files in <> bracket are searched in 'system' directories
B) Quote marks:- “header.h”
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")
In C the convention is that header files in " " are searched in user or local directories.
In it one file to be included in another .(FILE INCLUSION).
It can be used in two cases:
Case 1: If we have a very large program, the code is best divided int several different files,each containing a set of related functions.
Case 2: There are some functions and micros definitions that we need at most in all programs that we write.
Ex
I have this problem with a library. I want to add it to my Objective C (iOS) project, but their docs don't say how to do that. I simply copied it over. Now their main file has this:
#include <LIB/Class1.h>
#include <LIB/Class2.h>
...
It didn't work for me, so I changed each <> to "":
#include "LIB/Class1.h"
#include "LIB/Class2.h"
...
And with this syntax everything works fine, I can use the lib. I guess it's not a good practice, though. How should I add a library to a project so that it works without this modification?
In Xcode Build Setting, Header Search Paths (HEADER_SEARCH_PATHS) affects search path of #include <foo.h>, User Header Search Paths (USER_HEADER_SEARCH_PATHS) affects search path of #include "foo.h".
So, set HEADER_SEARCH_PATHS for your library's header path, #include <LIB/Class1.h> should be work.
Also, Always Search User Paths (ALWAYS_SEARCH_USER_PATHS) setting can change behavior for search path #include <foo.h>. When ALWAYS_SEARCH_USER_PATHS is YES, #include <LIB/Class1.h> should be work as well.
Add path to the libpath... "" relative from source and <>relative from the external libs
ALWAYS_SEARCH_USER_PATHS is deprecated now & should be avoided. Explicitly set
USER_HEADER_SEARCH_PATHS for ".h" include syntax header files.
SYSTEM_HEADER_SEARCH_PATHS for <.h> include syntax header files.
HEADER_SEARCH_PATHS: for fallback of USER_HEADER_SEARCH_PATHS for compilers which don't support separate include paths.
https://help.apple.com/xcode/mac/current/#/itcaec37c2a6?sub=deved642222b
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.
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.
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.
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.
#import <> vs ""
<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
Just stumbled upon the same problem, there are 2 types of search paths is Xcode:
User Header Search Paths
Header Search Paths
If you add your own include folders into Header Search Paths, you can use angled brackets without any problem.
Or set Always Search User Path to YES so you can use angle brackets.
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.
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
WHAT IS HEADER FILE ?
Header files contain definitions of functions and variables which can be incorporated into any C program by using the pre-processor #include statement. Standard header files are provided with each compiler, and cover a range of areas, string handling, mathematical, data conversion, printing and reading of variables.
Ex- #include it contain the information about input like scanf(),and out put like printf() function and etc in a compiler.
INCLUDE
1) #INCLUDE:-
It is a pre-processor that process before process of main function.
The main work of pre-processor is to initialize the environment of program i.e that is the program with the header file.
2).h:-
(Header file) A header file is a file with extension .h which contains C function declarations and macro definitions and to be shared between several source files.
Q) There are two types of header files: the files that the programmer writes and the files that come with your compiler ?
A)In a angular brackets
Angular-bracket form is for "global" includes -- those found somewhere on the include path passed to the compiler (e.g. #include)
It is used for using of library function which is all ready define in compiler.
In C the convention is that header files in <> bracket are searched in 'system' directories
B) Quote marks:- “header.h”
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")
In C the convention is that header files in " " are searched in user or local directories.
In it one file to be included in another .(FILE INCLUSION).
It can be used in two cases:
Case 1: If we have a very large program, the code is best divided int several different files,each containing a set of related functions.
Case 2: There are some functions and micros definitions that we need at most in all programs that we write.
Ex