Apply some easing into UIImageView animation - ios

Question

I am using the following to make a UIImageView slide a little bit forward, and then slide back farther for a parallax scrolling effect.
Code:
[UIView animateWithDuration:0.2f animations:^{
spendrBckGrnd.frame = CGRectMake(spendrBckGrnd.frame.origin.x + 20, 0, spendrBckGrnd.frame.size.width, spendrBckGrnd.frame.size.height);
}];
[UIView animateWithDuration:0.4f animations:^{
spendrBckGrnd.frame = CGRectMake(spendrBckGrnd.frame.origin.x - 80, 0, spendrBckGrnd.frame.size.width, spendrBckGrnd.frame.size.height);
}];
I am wondering how I might go about applying some easing into the animation, right now if just abruptly slides back and forth quickly. I would like to ease into and out of the sliding animations.

Answer 1

You need to do the second animation block after the first one completes.
[UIView animateWithDuration:0.2f animations:^{
spendrBckGrnd.frame = CGRectMake(spendrBckGrnd.frame.origin.x + 20, 0, spendrBckGrnd.frame.size.width, spendrBckGrnd.frame.size.height);
} completion:^{
[UIView animateWithDuration:0.2f animations:^(BOOL finished){
spendrBckGrnd.frame = CGRectMake(spendrBckGrnd.frame.origin.x - 80, 0, spendrBckGrnd.frame.size.width, spendrBckGrnd.frame.size.height);
}];
}];

Answer 2

This will do the trick:
[UIView animateWithDuration:0.2f delay:0 options:UIViewAnimationOptionCurveEaseInOut animations:^(void){
//do your animations
} completion:^(BOOL finished){
}];

Answer 3

Check out this tutorial on UIView animation
http://mobile.tutsplus.com/tutorials/iphone/ios-sdk_uiview-animations/
UIView has a method
// [UIView animateWithDuration:(NSTimeInterval) delay:(NSTimeInterval) options:(UIViewAnimationOptions)animations:^(void)animations completion:^(BOOL finished)completion];
typedef enum {
UIViewAnimationCurveEaseInOut, // slow at beginning and end
UIViewAnimationCurveEaseIn, // slow at beginning
UIViewAnimationCurveEaseOut, // slow at end
UIViewAnimationCurveLinear
}
[UIView animateWithDuration:0.6f
delay:0.1f
options:UIViewAnimationCurveEaseInOut
animations:^{
[starView setCenter:CGPointMake(0, 0)];
[starView setAlpha:0.0f];
}
completion:^(BOOL finished){
[starView removeFromSuperview];
points++;
}
];
Also check out this control on github that creates a parallax effect using a custom container view, much like the top view of Path's timeline.
https://github.com/modocache/MDCParallaxView