constraint animation doesn't animate as expected - animation

Question

the following code is used to move textfield position to an editing location on the app.
unfortunately it isn't producing the desired effect.
textfield1 moves in X to its finished location and then in y to its finished location.
i want both constraints to produce a diagonal motion of the textfield, but it's not working when tested on an iPhone.
the animation works but i end up with an inverted "L" shaped movement instead of a diagonal "\" motion
any suggestions how to fix this will be appreciated.
-(void)textFieldEditingPosition
{
NSLog(#"editing");
[_regular setNeedsUpdateConstraints];
switch (_activeTextField.tag)
{
case 1:
self.textField2WidthConstraint.constant =_regular.frame.size.width/4 -16;
self.textField2XConstraint.constant = -_regular.frame.size.width/4 - self.textField2WidthConstraint.constant/2 -8;
self.textField2YConstraint.constant = -(_regular.frame.size.height/2 -_inputView.frame.size.height/2);
_textField1YConstraint.constant = 0;
_textField1XConstraint.constant = 0;
_textField1WidthConstraint.constant = _placeHolderTextfield.frame.size.width;
break;
case 2:
self.textField1XConstraint.constant = (_regular.frame.size.width /4) /2;
self.textField1YConstraint.constant = -(_regular.frame.size.height/8 -8) ;
self.textField1WidthConstraint.constant = _regular.frame.size.width/4 * 3 -16;
self.textField2YConstraint.constant =0;
self.textField2XConstraint.constant = 0;
self.textField2WidthConstraint.constant = _placeHolderTextfield.frame.size.width;
break;
default:
break;
}
[UIView animateWithDuration:0.7
delay: 0.0
options: UIViewAnimationOptionCurveEaseInOut
animations:^{
[self.view layoutIfNeeded];
}
completion:nil];
}

Answer 1

I've managed to solve this issue as follows
first i turned on slow animation in the simulator.
this enabled me to see exactly what was happening.
The L shaped movement i was seeing was actually an illusion caused by the textfield width expanding as the textfield was moving to a new x and y position.
the expanding width kind of cancelled out the movement in x i was expecting to see.
by separating the width expansion into the animation completion, i get the result i need which is a diagonal movement of the textfield to the editing position.
the expansion of the textfield width happens in the completion block without animation, which is fine for me, as the textfield background is hidden, and the user sees only the placeholder text.
herewith the amended code:
-(void)textFieldEditingPosition
{
NSLog(#"editing");
[_regular setNeedsUpdateConstraints];
switch (_activeTextField.tag)
{
case 1:{
self.textField2WidthConstraint.constant =_regular.frame.size.width/4 -16;
self.textField2XConstraint.constant = -_regular.frame.size.width/4 - self.textField2WidthConstraint.constant/2 -8;
self.textField2YConstraint.constant = -(_regular.frame.size.height/2 -_inputView.frame.size.height/2);
_textField1YConstraint.constant = 0;
_textField1XConstraint.constant = 0;
[UIView animateWithDuration:0.7
delay: 0.0
options: UIViewAnimationOptionBeginFromCurrentState
animations:^{
[self.regular layoutIfNeeded];
}
completion:^(BOOL finished){
self->_textField1WidthConstraint.constant = self->_placeHolderTextfield.frame.size.width;
[self.regular layoutIfNeeded];}];
}
break;
case 2:{
self.textField1XConstraint.constant = (_regular.frame.size.width /4) /2;
self.textField1YConstraint.constant = -(_regular.frame.size.height/8 -8) ;
self.textField1WidthConstraint.constant = _regular.frame.size.width/4 * 3 -16;
self.textField2YConstraint.constant =0;
self.textField2XConstraint.constant = 0;
[UIView animateWithDuration:0.7
delay: 0.0
options: UIViewAnimationOptionBeginFromCurrentState
animations:^{
[self.regular layoutIfNeeded];
}
completion:^(BOOL finished){
self->_textField2WidthConstraint.constant = self->_placeHolderTextfield.frame.size.width;
[self.regular layoutIfNeeded];}];
}
break;
default:
break;
}
}
I'm sure there's a cleaner way of coding this, but it works so I'm relieved
thanks