Change a label on hover

uihovergesturerecognizer

is for iOS only ; and does work only for Catalyst.

See this other thread where I detail the solutions for MacOS:

https://forums.developer.apple.com/thread/126227

- trackingArea

or

- tooltip

Changing the label when you hover on it is quite simple with the first option:

In the subclass:

class LabelWithHelp: NSTextField { 

    var textForHover = "Some new text"     // This will be changed as needed
    var nonHoverText : String? 

    override init(frame frameRect: NSRect) {
        super.init(frame: frame)
        self.isEditable = false          // Behave like a label
        self.isSelectable = false
        self.nonHoverText = self.stringValue // The one with which label was created
    }

 
    override func draw(_ dirtyRect: NSRect) { 
        super.draw(dirtyRect) 
        // Drawing code here. If needed 
    } 

    // MARK: - Mouse Events 
   
    // --------------------- mouseEntered -------------------------------------------------------------- 
    //  Description: When hovering over label 
    //  Parameters 
    //      theEvent: NSEvent 
    //  Comments : 
    //      Need to have defined trackingArea 
    // ------------------------------------------------------------------------------------------------- 
   
    override func mouseEntered(with theEvent: NSEvent) { 
       
        super.mouseEntered(with: theEvent) 
        self.stringValue = textForHover
    } 

    // --------------------- mouseExited --------------------------------------------------------------  
    //  Description: Exit from hover  
    //  Parameters  
    //      theEvent: NSEvent  
    //  Comments :  
    // -------------------------------------------------------------------------------------------------  
    
    override func mouseExited(with theEvent: NSEvent) {    
        super.mouseExited(with: theEvent)  
        self.stringValue = nonHoverText        
    }  
    

}

I have created a new document > Cocoa Class and I put your code. Is it the right way? I got several errors. Sorry, probably I do not understand.

Please explain exactly what you did, eventually post the code.

- You created a new class definition in XCode, from File menu:

File > New > File

- Select MacOS and Cocoa class

- Subclass of NSTextField

- name LabelWithHelp

Is it how you proceeded ?

You should have got a new file with the following content

import Cocoa

class LabelClass: NSTextField {

    override func draw(_ dirtyRect: NSRect) {
        super.draw(dirtyRect)

        // Drawing code here.
    }
   
}

Now replace the content with the following (I have corrected a few errors)

import Cocoa

class LabelWithHelp: NSTextField {
   
    var textForHover = "Some new text"     // This will be changed as needed
    var nonHoverText : String?
   
    override func draw(_ dirtyRect: NSRect) {
        super.draw(dirtyRect)
        // Drawing code here. If needed
    }
   
    // MARK: - Mouse Events
   
    // --------------------- mouseEntered --------------------------------------------------------------
    //  Description: When hovering over label
    //  Parameters
    //      theEvent: NSEvent
    //  Comments :
    //      Need to have defined trackingArea
    // -------------------------------------------------------------------------------------------------
   
    override func mouseEntered(with theEvent: NSEvent) {
       
        super.mouseEntered(with: theEvent)
        nonHoverText = self.stringValue     // Save the actual content
        self.stringValue = textForHover     // replace in label
    }
   
    // --------------------- mouseExited --------------------------------------------------------------
    //  Description: Exit from hover
    //  Parameters
    //      theEvent: NSEvent
    //  Comments :
    // -------------------------------------------------------------------------------------------------
   
    override func mouseExited(with theEvent: NSEvent) {
        super.mouseExited(with: theEvent)
        self.stringValue = nonHoverText ?? ""     // replace with original text
    }
   }

In the view, in IB, create a label

Change its type to LabelWithHelp

In the ViewController where the label is:

- declare an IBOutlet for the label and a tracking area

    @IBOutlet weak var label: LabelWithHelp!

    fileprivate var labelTrackingArea    : NSTrackingArea?

Connect the IBOutlet to the label in IB

- in viewDidload, set the tracking area:

            labelTrackingArea = NSTrackingArea(rect: label.bounds, options: [NSTrackingArea.Options.mouseEnteredAndExited, NSTrackingArea.Options.cursorUpdate, NSTrackingArea.Options.activeInKeyWindow], owner: label, userInfo: nil)
            label.addTrackingArea(labelTrackingArea!)

Run

You should see the label change when you hover on it and return to its value when exiting.

Now I understand. It works very well. Thank you!

Question: can I use a TextField control instead a Label ?

• create a NSTextField in IB

• Give it LabelWithHelp type

• Connect to IBOutlet textField

• Create the trackingRect

Code Block 
    fileprivate var textFieldTrackingArea : NSTrackingArea?

• initialise it in viewDidLoad

Code Block 
        if textFieldTrackingArea == nil {
            textFieldTrackingArea = NSTrackingArea(rect: textField.bounds, options: [NSTrackingArea.Options.mouseEnteredAndExited, NSTrackingArea.Options.cursorUpdate, NSTrackingArea.Options.activeInKeyWindow], owner: textField, userInfo: nil)
            textField.addTrackingArea(textFieldTrackingArea!)
        }

how can I add a bound rect to the label ?