My aLog and dLog macros in Swift (to abbreviate NSLog)

Macros.swift

//
//  Macros.swift
//
//  Created by Xavier Muñiz on 6/12/14.

import Foundation


// dLog and aLog macros to abbreviate NSLog.
// Use like this:
//
//   dLog("Log this!")
//
#if DEBUG
    func dLog(message: String, filename: String = __FILE__, function: String = __FUNCTION__, line: Int = __LINE__) {
        NSLog("[\(filename.lastPathComponent):\(line)] \(function) - \(message)")
    }
#else
    func dLog(message: String, filename: String = __FILE__, function: String = __FUNCTION__, line: Int = __LINE__) {
    }
#endif
func aLog(message: String, filename: String = __FILE__, function: String = __FUNCTION__, line: Int = __LINE__) {
    NSLog("[\(filename.lastPathComponent):\(line)] \(function) - \(message)")
}

As per Jean Le Moignan http://stackoverflow.com/questions/24003291/ifdef-replacement-in-swift-language

Now, you must set the "DEBUG" symbol elsewhere, though. Set it in the "Swift Compiler - Custom Flags" section, "Other Swift Flags" line. You add the DEBUG symbol with the -D DEBUG entry.

As usual, you can set a different value when in Debug or when in Release.

I tested it in real code and it works; it doesn't seem to be recognized in a playground though.

Thanks! This works very well. I added a couple of functions to include a 'uLog', that shows an alert with the error.
This is my Macros.swift file now:

import Foundation
import UIKit


// dLog and aLog macros to abbreviate NSLog.
// Use like this:
//
//   dLog("Log this!")
//
#if DEBUG
    func dLog(message: String, filename: String = __FILE__, function: String = __FUNCTION__, line: Int = __LINE__) {
        NSLog("[\(filename.lastPathComponent):\(line)] \(function) - \(message)")
    }

    func uLog(message: String, filename: String = __FILE__, function: String = __FUNCTION__, line: Int = __LINE__) {
        let alertView = UIAlertView(title: "[\(filename.lastPathComponent):\(line)]", message: "\(function) - \(message)",  delegate:nil, cancelButtonTitle:"OK")
        alertView.show()
    }

#else
    func dLog(message: String, filename: String = __FILE__, function: String = __FUNCTION__, line: Int = __LINE__) { }

    func uLog(message: String, filename: String = __FILE__, function: String = __FUNCTION__, line: Int = __LINE__) { }

#endif

func aLog(message: String, filename: String = __FILE__, function: String = __FUNCTION__, line: Int = __LINE__) {
    NSLog("[\(filename.lastPathComponent):\(line)] \(function) - \(message)")
}

If you have a % sign in your message:

var strWithPercent = "ABC%DEF"
dLog("\(strWithPercent)")

This would crash.

Can be fixed by sending the computed string as a variable argument instead:

NSLog("%@","[\(filename.lastPathComponent):\(line)] \(function) - \(message)")

I also removed the file extension from the file name because it saves space :)

NSLog("%@","[\(filename.lastPathComponent.stringByDeletingPathExtension):\(line)] \(function) - \(message)")

This is what I ended up with

#if DEBUG
    func dLog(message: String, filename: String = __FILE__, function: String = __FUNCTION__, line: Int = __LINE__) {
        NSLog("%@","[\(filename.lastPathComponent.stringByDeletingPathExtension):\(line)] \(function) - \(message)")
    }
#else
    func dLog(message: String, filename: String = __FILE__, function: String = __FUNCTION__, line: Int = __LINE__) {
    }
#endif
func aLog(message: String, filename: String = __FILE__, function: String = __FUNCTION__, line: Int = __LINE__) {
    NSLog("%@","[\(filename.lastPathComponent.stringByDeletingPathExtension):\(line)] \(function) - \(message)")
}

Hey! This is an old thread, but has been useful to me. What I don't like with the above solutions is that the message variable (with lots of possible string interpolation) gets run regardless of whether DEBUG is set or not. To solve this, laze evaluation with @autoclosure can be used (see https://developer.apple.com/swift/blog/?id=4). When I do that, I get the following which seems to work well (and also works around the issue mentioned by @timzai)

import Foundation

// dLog and aLog macros to abbreviate NSLog.
// Use like this:
//
//   dLog("Log this!")
//
#if DEBUG
    func dLog(@autoclosure message:  () -> String, filename: String = __FILE__, function: String = __FUNCTION__, line: Int = __LINE__) {
    NSLog("[\(filename.lastPathComponent):\(line)] \(function) - %@", message())
    }
    #else
    func dLog(@autoclosure message:  () -> String, filename: String = __FILE__, function: String = __FUNCTION__, line: Int = __LINE__) {
    }
#endif
func aLog(message: String, filename: String = __FILE__, function: String = __FUNCTION__, line: Int = __LINE__) {
    NSLog("[\(filename.lastPathComponent):\(line)] \(function) - %@", message)
}

I went ahead an made String into AnyObject so that I could log out a dictionary.

Its sad that String in Swift 2.0 doesn't have lastPathComponent :(
We will need to use NSString if we still need that lastPathComponent.
https://forums.developer.apple.com/thread/13580

With Swift 2.2 you now use #filename, #line, etc. Here's what I have to include the fix for the % and the .lastPathComponent

import Foundation

#if DEBUG
func dLog(message: String, filename: String = #file, function: String = #function, line: Int = #line) {
        NSLog("%@","[\((filename as NSString).lastPathComponent):\(line)] \(function) - \(message)")
    }
#else
    func dLog(message: String, filename: String = #file, function: String = #function, line: Int = #line) {
    }
#endif
func aLog(message: String, filename: String = #file, function: String = #function, line: Int = #line) {
    NSLog("%@","[\((filename as NSString).lastPathComponent):\(line)] \(function) - \(message)")
}

I'm using it like this, a little more compact:

func dLog(message: String, filename: String = #file, function: String = #function, line: Int = #line) {
    #if DEBUG
        NSLog("[\((filename as NSString).lastPathComponent):\(line)] \(function) - \(message)")
    #endif
}

In Objective-C it was widely used as DLog, and ALog with capital D and A, so i am going to keep the same convention in Swift. in my own code