How do you get the Bundle Identifier from an application's name in Cocoa?

Question

Say you have the name of an application, Mail.app, how do you programmatically obtain com.apple.mail from the application name?

Answer 1

The following method will return an application's Bundle Identifier for a named application:

- (NSString *) bundleIdentifierForApplicationName:(NSString *)appName
{
    NSWorkspace * workspace = [NSWorkspace sharedWorkspace];
    NSString * appPath = [workspace fullPathForApplication:appName];
    if (appPath) {
        NSBundle * appBundle = [NSBundle bundleWithPath:appPath];
        return [appBundle bundleIdentifier];
    }
    return nil; 
}

For Mail you can call the method like so:

NSString * appID = [self bundleIdentifierForApplicationName:@"Mail"];

appID now contains com.apple.mail

Swift 5.1

import AppKit

func bundleIdentifier(forAppName appName: String) -> String? {

    let workspace = NSWorkspace.shared
    let appPath = workspace.fullPath(forApplication: appName)
    if let appPath = appPath {
        let appBundle = Bundle(path: appPath)
        return appBundle?.bundleIdentifier
    }
    return nil
}

// For Mail you can call the method like so:

let appID = bundleIdentifier(forAppName: "Mail")

---

Deprecation

The fullPathForApplication: / fullPath(forApplication:) method has been deprecated in macOS 10.15 - it is unclear what the answer is going forward.

Answer 2

Expanding on Francesco Germinara's answer in Swift 4, macOS 10.13.2:

extension Bundle {
    class func bundleIDFor(appNamed appName: String) -> String? {
        if let appPath = NSWorkspace.shared.fullPath(forApplication: appName) {
            if let itsBundle = Bundle(path: appPath) { // < in my build this condition fails if we're looking for the ID of the app we're running...
                if let itsID = itsBundle.bundleIdentifier {
                    return itsID
                }
            } else {
                //Attempt to get the current running app.
                //This is probably too simplistic a catch for every single possibility
                if let ownID =  Bundle.main.bundleIdentifier {
                    return ownID
                }
            }
        }
        return nil
    }
}

Placing it your Swift project, you can call it like this:

let id = Bundle.bundleIDFor(appNamed: "Mail.app")

or

let id = Bundle.bundleIDFor(appNamed: "Mail")