Make Animation Slow at the Beginning

[UIView setAnimationDuration:0.5];

[UIView setAnimationDelay:1.0];

[UIView setAnimationCurve:UIViewAnimationCurveEaseIn];

mainImage.alpha = 0.0f;

[UIView commitAnimations];

Details:

UIViewAnimationCurveEaseInOut: The default Value, slow at beginning and end of animation

UIViewAnimationCurveEaseIn: Slow at beginning, the speeds up

UIViewAnimationCurveEaseOut: Animation slows at end of animation

UIViewAnimationCurveLinear: Uniform speed throughout duration