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

Or slight function modification with:

func logFunctionName(file:String = __FILE__, fnc:String = __FUNCTION__, line:(Int)=__LINE__) {
    var className = file.lastPathComponent.componentsSeparatedByString(".")
    println("\(className[0]):\(fnc):\(line)")

}

/* will produce an execution trace like: AppDelegate:application(_:didFinishLaunchingWithOptions:):18 Product:init(type:name:year:price:):34 FirstViewController:viewDidLoad():15 AppDelegate:applicationDidBecomeActive:62 */

Answer 2

Swift 4
Here's my approach:

func pretty_function(_ file: String = #file, function: String = #function, line: Int = #line) {

    let fileString: NSString = NSString(string: file)

    if Thread.isMainThread {
        print("file:\(fileString.lastPathComponent) function:\(function) line:\(line) [M]")
    } else {
        print("file:\(fileString.lastPathComponent) function:\(function) line:\(line) [T]")
    }
}

Make this a global function and just call

pretty_function()

Bonus: You will see the thread is executed on, [T] for a background thread and [M] for the Main thread.

Answer 3

Swift 3.0

public func LogFunction<T>(object: T, filename: String = #file, line: Int = #line, funcname: String = #function) {
    let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = "MM/dd/yyyy HH:mm:ss:SSS"
    let process = ProcessInfo.processInfo()
    let threadId = "?"
    print("\(dateFormatter.string(from:Date())) \(process.processName) [\(process.processIdentifier):\(threadId)] \(filename)(\(line)) \(funcname)::: \(object)")
}

Answer 4

I prefer to define a global log function:

[Swift 3.1]

func ZYLog(_ object: Any?, filename: String = #file, line: Int = #line, funcname: String = #function) {
    #if DEBUG
    print("****\(Date()) \(filename)(\(line)) \(funcname):\r\(object ?? "nil")\n")
    #endif
}

[Swift 3.0]

func ZYLog<T>(_ object: T?, filename: String = #file, line: Int = #line, funcname: String = #function) {
    #if DEBUG
    print("****\(Date()) \(filename)(\(line)) \(funcname):\r\(object)\n")
    #endif
}

[Swift 2.0]

func ZYLog<T>(object: T, filename: String = __FILE__, line: Int = __LINE__, funcname: String = __FUNCTION__) {
    println("****\(filename.lastPathComponent)(\(line)) \(funcname):\r\(object)\n")
}

the output is something like:

****ZYHttpSessionManager.swift(78) POST(_:parameters:success:failure:):
[POST] user/login, {
    "auth_key" = xxx;
    "auth_type" = 0;
    pwd = xxx;
    user = "xxx";
}

****PointViewController.swift(162) loadData():
review/list [limit: 30, skip: 0]

****ZYHttpSessionManager.swift(66) GET(_:parameters:success:failure:):
[GET] review/list, {
    "auth_key" = xxx;
    uuid = "xxx";
}

Answer 5

Starting from Swift 2.2 we should use:

• #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.

From The Swift Programming Language (Swift 3.1) at page 894.

func specialLiterals() {
    print("#file literal from file: \(#file)")
    print("#function literal from function: \(#function)")
    print("#line: \(#line) -> #column: \(#column)")
}
// Output:
// #file literal from file: My.playground
// #function literal from function: specialLiterals()
// #line: 10 -> #column: 42