NSLog the method name with Objective-C in iPhone

Currently, we are defining ourselves an extended log mechanism to print out the class name and the source line number of the log.

#define NCLog(s, ...) NSLog(@"<%@:%d> %@", [[NSString stringWithUTF8String:__FILE__] lastPathComponent], \
    __LINE__, [NSString stringWithFormat:(s), ##__VA_ARGS__])

For example, when I call NCLog(@"Hello world"); The output will be:

<ApplicationDelegate:10>Hello world

Now I also want to log out the method name like:

<ApplicationDelegate:applicationDidFinishLaunching:10>Hello world

So, this would make our debugging become easier when we can know which method is getting called. I know that we also have Xcode debugger but sometimes, I also want to do debugging by logging out.

print(__FUNCTION__) // Swift
NSLog(@"%@", NSStringFromSelector(_cmd)); // Objective-C

Swift 3 and above

print(#function)

To technically answer your question, you want:

NSLog(@"<%@:%@:%d>", NSStringFromClass([self class]), NSStringFromSelector(_cmd), __LINE__);

Or you could also do:

NSLog(@"%s", __PRETTY_FUNCTION__);

tl;dr

NSLog( @"ERROR %@ METHOD %s:%d ", @"DescriptionGoesHere", __func__, __LINE__ );

Details

Apple has a Technical Q&A page: QA1669 - How can I add context information - such as the current method or line number - to my logging statements?

To assist with logging:

• The C preprocessor provides a few macros.
• Objective-C provides expressions (methods).
  • Pass the implicit argument for the current method's selector: _cmd

As other answers indicated, to merely get the current method's name, call:

NSStringFromSelector(_cmd)

To get the current method name and current line number, use these two macros __func__ and __LINE__ as seen here:

NSLog(@"%s:%d someObject=%@", __func__, __LINE__, someObject);

Another example… Snippets of code I keep in Xcode's Code Snippet Library:

NSLog( @"ERROR %@ METHOD %s:%d ", @"DescriptionGoesHere", __func__, __LINE__ );

…and TRACE instead of ERROR…

NSLog( @"TRACE %@ METHOD %s:%d ", @"DescriptionGoesHere", __func__, __LINE__ );

…and a longer one using a soft-coded description passing a value ([rows count])…

NSLog( @"TRACE %@ METHOD %s:%d.", [NSString stringWithFormat:@"'Table of Contents.txt' file's count of Linefeed-delimited rows: %u.", [rows count]] , __func__, __LINE__ );

Preprocessor macros for logging

Note the use of a pair of underscore characters around both sides of the macro.

| Macro                | Format   | Description
func               %s         Current function signature
LINE               %d         Current line number
FILE               %s         Full path to source file
PRETTY_FUNCTION    %s         Like func, but includes verbose
type information in C++ code.

Expressions for logging

| Expression                       | Format   | Description
NSStringFromSelector(_cmd)         %@         Name of the current selector
NSStringFromClass([self class])    %@         Current object's class name
[[NSString                         %@         Source code file name
stringWithUTF8String:FILE]

lastPathComponent]
[NSThread callStackSymbols]        %@         NSArray of stack trace

---

Logging Frameworks

Some logging frameworks may help with getting current method or line number as well. I'm not sure, as I've used a great logging framework in Java (SLF4J + LogBack) but not Cocoa.

See this question for links to various Cocoa logging frameworks.

Name of Selector

If you have a Selector variable (a SEL), you can print its method name ("message") in either of two ways as described by this Codec blog post:

• Using Objective-C call to NSStringFromSelector:
  NSLog(@"%@", NSStringFromSelector(selector) );
• Using straight C:
  NSLog(@"%s", selector );

---

This information drawn from the linked Apple doc page as of 2013-07-19. That page had been last updated 2011-10-04.

NSLog(@"%@", NSStringFromSelector(_cmd)); // Objective-C
print(__FUNCTION__) // Swift

It's actually just as simple as:

printf(_cmd);

For some reason iOS allows _cmd to be passed as a literal char with not even a compile warning. Who knows

In Swift 4:

func test(){

print(#function)

}

test() //print the value "test()"