Shake visual effect on iPhone (NOT shaking the device)

Question

On login failure, I\'d prefer to avoid showing an alert, it\'s too fleeting. Showing the alert and then showing the text somewhere on the login screen seems like duplication

Answer 1

Using Auto Layout, I adapted Chris Miles' answer but animated NSLayoutConstraints like this:

NSLayoutConstraint *left  = ...
NSLayoutConstraint *right = ...

[UIView animateWithDuration:0.08 delay:0.0 options:UIViewAnimationOptionAutoreverse|UIViewAnimationOptionRepeat animations:^{
    [UIView setAnimationRepeatCount:3];
    left.constant  = 15.0;
    right.constant = 25.0;
    [self.view layoutIfNeeded];
} completion:^(BOOL finished) {
    if (finished) {
        [UIView animateWithDuration:0.08 animations:^{
            left.constant  = 20.0;
            right.constant = 20.0;
            [self.view layoutIfNeeded];
        } completion:NULL];
    }
}];