iOS Swift Label Frame Height Not Updating Correctly

Question

I have a Label whose text changes each time the user clicks a Button. However, the Label.frame.height value does not update immediately even though the Label content has changed. The function to change the Label is called in multiple places, yet the height ONLY updates just inside the @IBAction block, and its value lags one click cycle. My code is as follows:

func changeLabelText() {
//Here I have an algorithm (not shown) that generates myMutableString 
Label.attributedText = myMutableString  //Label is updated.
}


@IBAction func changeLabelButton(sender: UIButton) {
print("1. Height = ", Label.frame.height) //Height updates here, but it's the old value.  
changeLabelText()  //Label is updated.
print("2. Height = ", Label.frame.height) //Returns same height as Line 1!!
}


override func viewDidLoad() {
super.viewDidLoad()
print("3. Height = ", Label.frame.height) //Initially, height is 21.0 when ViewController first loads.
changeLabelText() //Label is updated.
print("4. Height = ", Label.frame.height) //Returns height = 21.0, even though simulator shows Label updated!!
}

In summary, this is what's happening:

1. User clicks Button, Label displays new text, but frame.height is unchanged.

2. User clicks Button again, Label text changes again, frame.height updates this time, but updates to the old value it should've had on Step 1.

I'm relatively new to Swift, and any help with this is appreciated.

Answer 1

Call these methods immediately after changing the text

label.setNeedsLayout()
label.layoutIfNeeded()

this will give you the correct frame.