uitextfield动画宽度约束

Question

I have this code to animate a width constraint of a UITextField

self.myTextFieldWidthConstraint.constant = 200
UIView.animateWithDuration(2, delay: 0.0, options: UIViewAnimationOptions.CurveLinear, animations: { () -> Void in
    self.viewContainer.layoutIfNeeded()
}, completion: nil)

It works fine, the only issue is that if there is text inside the text field, during the animation it shrinks in character width and then re-adjusts to the correct size. The placeholder text does not have the same issue.

Here is a gif: http://makeagif.com/mr4u1D

Answer 1

Fahim, you can prevent the text scaling by resigning the first responder before you animate the width change, for example with:

[self.myTextField resignFirstResponder]

or, more generally:

[self.view endEditing:YES]

Answer 2

This is happening because field is already focused while doing the animation. My assumption is that you are doing your animation in:

func textFieldDidBeginEditing(textField: UITextField) 

But you should do it instead in:

func textFieldShouldBeginEditing(textField: UITextField) -> Bool