How to Get Line Number and Function Name in Swift Language

Is there a way to get line number and function name in Swift language?

The Swift Language Reference defines a few "special literals" that offer this behavior:

Literal        Type     Value

#file          String   The name of the file in which it appears.
#line          Int      The line number on which it appears.
#column        Int      The column number in which it begins.
#function      String   The name of the declaration in which it appears.

How to print out the method name and line number in swift

Literal        Type     Value

#file          String   The name of the file in which it appears.
#line          Int      The line number on which it appears.
#column        Int      The column number in which it begins.
#function      String   The name of the declaration in which it appears.
#dsohandle     UnsafeMutablePointer   The dso handle.

Example

print("Function: \(#function), line: \(#line)")

With default values in parameters you can also create a function

public func track(_ message: String, file: String = #file, function: String = #function, line: Int = #line ) { 
    print("\(message) called from \(function) \(file):\(line)") 
}

which can be used like this

track("enters app")

In Swift 2.1

 Literal        Type     Value

__FILE__       String   The name of the file in which it appears.
__LINE__       Int      The line number on which it appears.
__COLUMN__     Int      The column number in which it begins.
__FUNCTION__   String   The name of the declaration in which it appears.

for more info see the documentation

Log line number and method name in Swift

Swift provides some expressions in order to log, among others line number and method name:

Literal     Type    Value
#file       String  The name of the file in which it appears.
#line       Int     The line number on which it appears.
#column     Int     The column number in which it begins.
#function   String  The name of the declaration in which it appears.

For example:

func logFunctionName(string: String = #function) {
    print(string)
}
func myFunction() {
    logFunctionName() // Prints "myFunction()".
}

For more information, check the official documentation

Finding parent caller file, line number, and function in Swift

You can use default argument values. It would look something like this:

func formatError(_ except: Error,
    function: StaticString = #function,
    file: StaticString  = #file,
    line: UInt  = #line) -> String {
    return "[\(file).\(line):\(function)] ERROR: \(except.localizedDescription)"
}

How can I find a line number in Xcode?

You can go to:

Xcode > Preferences > Text Editing

then tick "Line numbers". Go to your method and you'll see the appropriate line number shown in the left-hand border of the text editor.

How to print out the method name and line number and conditionally disable NSLog?

Here are some useful macros around NSLog I use a lot:

#ifdef DEBUG
#   define DLog(fmt, ...) NSLog((@"%s [Line %d] " fmt), __PRETTY_FUNCTION__, __LINE__, ##__VA_ARGS__)
#else
#   define DLog(...)
#endif

// ALog always displays output regardless of the DEBUG setting
#define ALog(fmt, ...) NSLog((@"%s [Line %d] " fmt), __PRETTY_FUNCTION__, __LINE__, ##__VA_ARGS__)

The DLog macro is used to only output when the DEBUG variable is set (-DDEBUG in the projects's C flags for the debug confirguration).

ALog will always output text (like the regular NSLog).

The output (e.g. ALog(@"Hello world") ) will look like this:

-[LibraryController awakeFromNib] [Line 364] Hello world

How can I access the current line number in objective-c?

Here you are a little piece of useful code:

#define DLog(fmt, ...) NSLog((@"%s [Line %d] " fmt), __PRETTY_FUNCTION__, __LINE__, ##__VA_ARGS__);