Is there a way to suppress warnings in Xcode?

Question

Is there a way to suppress warnings in Xcode?

For example I am calling an undocumented method and since the method is not in the header I get a warning on compile. I know I can add it to my header to stop the warning, but I am wondering if there is a way other than adding it to the header (so I can keep the headers clean and standard) to suppress the warning? A pragma or something?

Bottomless

yes, sometimes you fall in need to say to compiler not to warn you about any unused variable (according to him) but actually you might be using it as BOOL ok = [[NSCalendar currentCalendar] rangeOfUnit:NSMonthCalendarUnit startDate:&d interval:NULL forDate:self]; NSAssert1(ok, @"Failed to calculate the first day the month based on %@", self); – Womb

Answer 1

To disable warnings on a per-file basis, using Xcode 3 and llvm-gcc-4.2 you can use:

#pragma GCC diagnostic ignored "-Wwarning-flag"

Where warning name is some gcc warning flag.

This overrides any warning flags on the command line. It doesn't work with all warnings though. Add -fdiagnostics-show-option to your CFLAGS and you can see which flag you can use to disable that warning.

Distinctly

Easy way to get the warning code: go to the Log Navigator (Command+7), select the topmost build, expand the log (the '=' button on the right), and scroll to the bottom. – Cervine

For those who care, an educational reference of GCC warning options: gcc.gnu.org/onlinedocs/gcc/Warning-Options.html – Puseyism

It seems #pragma GCC diagnostic ignored "-Wwarning-flag" is removed already – Carliecarlile

@Carliecarlile its still there, you just need to replace warning-flag with one of the warnings listed in gcc.gnu.org/onlinedocs/gcc/Warning-Options.html – Clupeid

In Xcode 14+ look for the warning code in the report Navigator (Command+9) – Landwehr

Answer 2

there is a simpler way to suppress Unused variable warnings:

#pragma unused(varname)

EDIT: source: http://www.cocoadev.com/index.pl?XCodePragmas

UPDATE: I came accross with a new solution, a more robust one

1. Open the Project > Edit Active Target> Build tab.
2. Under User-Defined: find (or create if you don't find one )the key : GCC_WARN_UNUSED_VARIABLE set it to NO.

EDIT-2 Example:

BOOL ok = YES;
NSAssert1(ok, @"Failed to calculate the first day the month based on %@", self);

the compiler shows unused variable warning for ok.

Solution:

BOOL ok = YES;
#pragma unused(ok)
NSAssert1(ok, @"Failed to calculate the first day the month based on %@", self);

PS: You can also set/reset other warning: GCC_WARN_ABOUT_RETURN_TYPE : YES/NO

Womb

Even simpler is to put __unused before the variable declaration. – Particularize

@mark-leonard should've been a separate answer, I've been looking for this for days. I had to start reading comments out of desperation. Thank you. – Internal

Answer 3

For gcc you can use

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wshadow-ivar"
// your code
#pragma GCC diagnostic pop

You can learn about GCC pragma here and to get the warning code of a warning go to the Report Navigator (Command+9), select the topmost build, expand the log (the '=' button on the right), and scroll to the bottom and there your warning code is within square brackets like this [-Wshadow-ivar]

For clang you can use

#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wshadow-ivar"
// your code
#pragma clang diagnostic pop

Ruination

Clang supports GCC’s pragma for compatibility with existing source code. So you just need to write gcc format pragma. – Speakeasy

Starting with Xcode 5.0, Clang was the only compiler provided. So you may ned to use clang format pragma now. – Carliecarlile

Answer 4

In order to surpress a warning for an individual file do the following:

select the file in the xcode project. press get info go to the page with build options enter -Wno- to negate a warning:

-Wno-

e.g.

-Wno-unused-parameter

You can get the name of the warning if you look on the project settings look at the GCC warnings located at the bottom of the build tab page, by clicking on each warning it will tell you the warning parameter name:

e.g.

Warn whenever a function parameter is unused aside from its declaration. [GCC_WARN_UNUSED_PARAMETER, -Wunused-parameter]

Recommend

This is an excellent solution for when you've included code from a codebase you don't want to modify that happens to trigger compiler warnings... – Chukar

Seems like a great way, but any ideas how you do this in XCode 4 – Adinaadine

Found my solution here for XCode 4 #6057692 – Adinaadine

if you need a supress warning for just one problem, like mine: ...m:45:69: Incompatible pointer types sending... i opened the build explanation and find this warning: [-Wincompatible-pointer-types] i just renamed it to -Wno-incompatible-pointer-types and added as a flag to my .m file... boom no more warnings... +10 if i could – Tamtama

Answer 5

With Objective-C, a number of serious errors only appear as warnings. Not only do I never disable warnings, I normally turn on "Treat warnings as errors" (-Werror).

Every type of warning in your code can be avoided by doing things correctly (normally by casting objects to the correct type) or by declaring prototypes when you need them.

Noni

While this is good general advice, it does not answer the question. Not all warnings are critical or serious; many are quite trivial. Suppose that one is required to use a third-party library and cannot modify it, for whatever reason (legacy codebase, code meant to be linked by third party, boss stipulation, etc.) Suppressing specific trivial warnings is quite acceptable in these cases. – Indoor

Answer 6

To get rid of the warning: try creating a category interface for the object in question

@interface NSTheClass (MyUndocumentedMethodsForNSTheClass)

-(id)theUndocumentedMethod;
@end
...

@implementation myClass : mySuperclass

-(void) myMethod {
...
   [theObject theUndocumentedMethod];
...
}

As an aside, I strongly advise against calling undocumented methods in shipping code. The interface can and will change, and it will be your fault.

Claybourne

I do this as well. I call my category "Private" and put it at the top of the .m file... It serves as a way to forward declare the methods that are only used within the file. I agree that a private header file would be more standard, but having to constantly bounce between files for something that really should be wholly contained (private) to the implementation is annoying. – Hubblebubble

So, it turns out that you can use the old C trick of just implementing the method before anything uses it. Then you've got yourself a file-local method. I think that it's not private though, so other files could possibly send a message to the selector you define in this way. – Claybourne

Answer 7

http://nshipster.com/pragma/#inhibiting-warnings - skip to inhibiting warnings section

Tirewoman

Answer 8

Create a new, separate header file called 'Undocumented.h' and add it to your project. Then create one interface block for each class you want to call undocumented functions on and give each a category of '(Undocumented)'. Then just include that one header file in your PCH. This way your original header files remain clean, there's only one other file to maintain, and you can comment out one line in your PCH to re-enable all the warnings again.

I also use this method for depreciated functions in 'Depreciated.h' with a category of '(Depreciated)'.

the best part is you can selectively enable/disable individual warnings by commenting or uncommenting the individual prototypes.

Fear

Answer 9

Suppressing that particular warning is not safe. The compiler needs to know the types of the arguments and returns to a method to generate correct code.

For example, if you're calling a method like this

[foo doSomethingWithFloat:1.0];

that takes a float, and there is no prototype visible, then the compiler will guess that the method takes a double, not a float. This can cause crashes and incorrectly interpreted values. In the example above, on a little endian machine like the intel machines, the receiver method would see 0 passed, not 1.

You can read why in the i386 ABI docs, or you can just fix your warnings. :-)

Wozniak

Good advice, but doesn't actually answer the question, as per above. – Indoor