Logger on Xcode console

Question

newwbee OP

Created Nov ’22

Replies 4

Boosts 1

Views 3.8k

Participants 4

Overview:

I am logging some messages using Logger
I would like these messages to be printed on to Xcode without the timestamp and other details
I want only the message to be displayed

Questions:

How can I display only the message on the Xcode console (see preferred output)?
Is there a setting in Xcode to remove the timestamp prefix?
Is there an alternate approach?

Note:

I need to use Logger because this app would be released, so print is not an option.

Example Code

import SwiftUI
import os
struct ContentView: View {
    
    let logger = Logger(subsystem: "MyApp", category: "MyCategory")
    
    var body: some View {
        Text("Hello, world!")
            .onAppear {
                logger.debug("content view displayed")
            }
    }
}

Actual Output:

2022-11-25 18:41:10.116408+0800 Demo[36175:5518724] [MyCategory] content view displayed

Preferred Output:

One of the following would be ideal:

content view displayed

Demo[36175:5518724] [MyCategory] content view displayed

My Failed Attempt

I event tried to use print in debug mode, but couldn't make it compile:

Following is my failed attempt:

import os

#if DEBUG
struct Logger {
    
    let subsystem: String
    let category: String
    
    func debug(_ message: String) {
        print(message)
    }
    
    //This will not help:
//    func debug(_ message: OSLogMessage) {
//        print(message)
//    }
}
#endif

Answered by DTS Engineer in 737607022

For general advice on this subject, see Your Friend the System Log. The limitation mentioned there (r. 32863680) means you have to choose between using the system log and getting the exact output you want in the Xcode console pane. IMO it’s better to choose the system log, and use Console app to get your nice output, but there are differences in opinion.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

Boost

Answer 1

newwbee OP

Nov ’22

Non-sensitive logging (Public)

This doesn't work in my following case:

import SwiftUI
import os

struct ContentView: View {
    
    let logger = Logger(subsystem: "MyApp", category: "MyCategory")
    let itemName = "something non-sensitive"
    
    var body: some View {
        Text("Hello, world!")
            .onAppear {
                logger.debug("content view displayed")
                logger.debug("Item name = \(itemName, privacy: .public)")
            }
    }
}

0

Answer 2

darkpaw OP

Nov ’22

If you put the #if DEBUG ... #endif around the struct Logger { ... } you're telling the compiler to only include that code if the app is being built for DEBUG, not RELEASE, so it will fail if you try to build for RELEASE.

Regardless of how the app is going to be built if you're calling a function that function has to exist.

You simply need to move the #if DEBUG ... #endif to the bit that should only be printed when you're in DEBUG mode, i.e.:

struct Logger {
	let subsystem: String
	let category: String

	func debug(_ message: String) {
#if DEBUG
		print(message)
#endif
	}
}

So, the code will compile and the message will only be printed if you're in DEBUG.

0

Answer 3

darkpaw OP

Nov ’22

Well of course it doesn't work. Even though you've got import os at the top of the file, by creating struct Logger further down you've ignored the os Logger entirely and used the one you've just created in your file, so it doesn't know how to interpolate \(itemName, privacy: .public).

If you want to use the os Logger, you need to remove your struct Logger.

I can't understand why you'd want to remove the timestamps, and if you do seriously need to do this, you'll have to use an extension and override the message, which might be difficult to do and gain you very little.

0

Answer 4

DTS Engineer OP

Apple

Nov ’22

Accepted Answer

For general advice on this subject, see Your Friend the System Log. The limitation mentioned there (r. 32863680) means you have to choose between using the system log and getting the exact output you want in the Xcode console pane. IMO it’s better to choose the system log, and use Console app to get your nice output, but there are differences in opinion.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

1