How to change color of status bar item title in Objective-C/Cocoa?

Use NSStatusItem's -setAttributedTitle method, and give it an NSAttributedString of the appropriate color:

NSDictionary *titleAttributes = [NSDictionary dictionaryWithObject:[NSColor blueColor] forKey:NSForegroundColorAttributeName];
NSAttributedString* blueTitle = [[NSAttributedString alloc] initWithString:@"myTitle" attributes:titleAttributes];

statusItem = [[[NSStatusBar systemStatusBar] statusItemWithLength:NSSquareStatusItemLength] retain];
[statusItem setAttributedTitle:blueTitle];
[blueTitle release];

Swift 4 version:

let attributes = [NSAttributedStringKey.foregroundColor: NSColor.blue]
let attributedText = NSAttributedString(string: "myTitle", attributes: attributes)

let statusItem = NSStatusBar.system.statusItem(withLength: NSStatusItem.variableLength)
statusItem.attributedTitle = attributedText