Is there a Swift alternative for NSLog(@“%s”, __PRETTY_FUNCTION__)

Question

In Objective C you can log the method that is being called using:

NSLog(@\"%s\", __PRETTY_FUNCTION__)

Usually this is used from a logging m

Answer 1

Another way to log function call:

NSLog("\(type(of:self)): %@", #function)

Answer 2

I use, this is all that is required in a swift file, all other files will pick it up (as a global function). When you want to release the application just comment out the line.

import UIKit

func logFunctionName(file:NSString = __FILE__, fnc:String = __FUNCTION__){  
    println("\(file.lastPathComponent):\(fnc)")
}

Answer 3

Swift has #file, #function, #line and #column. From Swift Programming Language:

#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.

Answer 4

As of XCode beta 6, you can use reflect(self).summary to get the class name and __FUNCTION__ to get the function name, but things are a bit mangled, right now. Hopefully, they'll come up with a better solution. It might be worthwhile to use a #define until we're out of beta.

This code:

NSLog("[%@ %@]", reflect(self).summary, __FUNCTION__)

gives results like this:

2014-08-24 08:46:26.606 SwiftLessons[427:16981938] [C12SwiftLessons24HelloWorldViewController (has 2 children) goodbyeActiongoodbyeAction]

EDIT: This is more code, but got me closer to what I needed, which I think is what you wanted.

func intFromString(str: String) -> Int
{
    var result = 0;
    for chr in str.unicodeScalars
    {
        if (chr.isDigit())
        {
            let value = chr - "0";
            result *= 10;
            result += value;
        }
        else
        {
            break;
        }
    }

    return result;
}


@IBAction func flowAction(AnyObject)
{
    let cname = _stdlib_getTypeName(self)
    var parse = cname.substringFromIndex(1)                                 // strip off the "C"
    var count = self.intFromString(parse)
    var countStr = String(format: "%d", count)                              // get the number at the beginning
    parse = parse.substringFromIndex(countStr.lengthOfBytesUsingEncoding(NSUTF8StringEncoding))
    let appName = parse.substringToIndex(count)                             // pull the app name

    parse = parse.substringFromIndex(count);                                // now get the class name
    count = self.intFromString(parse)
    countStr = String(format: "%d", count)
    parse = parse.substringFromIndex(countStr.lengthOfBytesUsingEncoding(NSUTF8StringEncoding))
    let className = parse.substringToIndex(count)
    NSLog("app: %@ class: %@ func: %@", appName, className, __FUNCTION__)
}

It gives output like this:

2014-08-24 09:52:12.159 SwiftLessons[1397:17145716] app: SwiftLessons class: ViewController func: flowAction

Answer 5

Here is an updated Swift 2 answer.

func LogW(msg:String, function: String = __FUNCTION__, file: String = __FILE__, line: Int = __LINE__){
    print("[WARNING]\(makeTag(function, file: file, line: line)) : \(msg)")
}

private func makeTag(function: String, file: String, line: Int) -> String{
    let url = NSURL(fileURLWithPath: file)
    let className:String! = url.lastPathComponent == nil ? file: url.lastPathComponent!
    return "\(className) \(function)[\(line)]"
}

Example of use:

LogW("Socket connection error: \(error)")

Answer 6

Swift 3.x+

If you don't want the entire file name then here's a quick fix for that.

func trace(fileName:String = #file, lineNumber:Int = #line, functionName:String = #function) -> Void {
    print("filename: \(fileName.components(separatedBy: "/").last!) function: \(functionName) line: #\(lineNumber)")
}

filename: ViewController.swift function: viewDidLoad() line: #42