Change NSTextField text color with fade animation - Cocoa

Question

I am trying to change NSTextField text color with fade animation by using NSAnimationContext. But it's not working. Please help me to solve this issue. Thanking you all!

Code:

 override func viewDidLoad() {
        super.viewDidLoad()
 
        label!.animator().textColor = NSColor.black
    }
    
    @IBAction func changeColor(_ sender: NSButton){
        
        NSAnimationContext.runAnimationGroup { (context) in
            
            context.duration = 1.0
            label!.animator().textColor = NSColor.red
        }
   }

Answer 1

Here is the outline of one possible solution:

• Subclass NSAnimation, say with TextColorAnimation
• Have the init take the NSTextField and final NSColor
• Override currentProgress as per NSAnimation docs to (a) call the super implementation and (b) set the intermediate color and display the NSTextField
• Use NSColor.blend(...) to determine the intermediate color
• start this NSAnimation

You should get a nice smooth color transition. HTH

Answer 2

Update the color and alpha value in the completion handler:

@IBAction func changeColor(_ sender: NSButton){
    NSAnimationContext.runAnimationGroup({ [self] context in
        context.duration = 1.0
        context.timingFunction = CAMediaTimingFunction(name: .easeOut)
        label.animator().alphaValue = 0.0
        label.animator().textColor = NSColor.black
    }, completionHandler: { [self] in
        NSAnimationContext.runAnimationGroup({ [self] context in
            context.duration = 1.0
            context.timingFunction = CAMediaTimingFunction(name: .easeIn)
            label.animator().alphaValue = 1.0
            label.animator().textColor = NSColor.red
        }, completionHandler: {
        })
    })
 }