Question

iPad – iOS 5.1 – Xcode 4.3.2

When the keyboard pop ups I animate the y origin of my UIImageView up by “x”
When the keyboard goes down, i animate it back down by the same “x”

So the keyboard pops up, the image goes up by X, the keyboard comes down, the image goes down by x, but it doesn’t end up in the same place!. You go up 60, down 60, and you’re not in the same place! it’s further down, as if the coordinate system changed between the appearance of the keyboard and the disappearance of it. It absolutely drives me crazy. I can’t understand why this happens.

//add gesture recognizer when keyboard appears
-(void)keyboardWillShow:(NSNotification *) note {

    [self.view addGestureRecognizer:tapRecognizer];

    // Setup the animation
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:0.3f];
    [UIView setAnimationCurve:UIViewAnimationOptionCurveEaseInOut];
    [UIView setAnimationBeginsFromCurrentState:YES];

    // The transform matrix: Logo Image

    CGAffineTransform moveLogo = CGAffineTransformMakeTranslation(0, -60);
    self.logoImageView.transform = moveLogo;

    // Commit the changes
    [UIView commitAnimations];  
}

//add gesture recognizer when keyboard appears
-(void)keyboardWillHide:(NSNotification *) note {

    [self.view removeGestureRecognizer:tapRecognizer];

    // Setup the animation
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:0.3f];
    [UIView setAnimationCurve:UIViewAnimationOptionCurveEaseInOut];
    [UIView setAnimationBeginsFromCurrentState:YES];

    // The transform matrix: Logo Image

    CGAffineTransform moveLogo = CGAffineTransformMakeTranslation(0, 60);
    self.logoImageView.transform = moveLogo;

    // Commit the changes
    [UIView commitAnimations];  
}

Answer 1

That’s because you are not translating it, when you use CGAffineTransformMakeTranslation you are saying Give me these coordinates not give me this offset. In other words, make translation gives you the translation from the identity matrix. The function you want is CGAffineTransformTranslate. This will apply the translation to the current transform (passed as the first argument).