Change UIView background color using animation
I want to change the background color UIView
using a transition animation. For example, if the image is red, I change it to blue. The blue color will move up from the bottom of the screen and fill the entire screen. I thought about this by making it the UIView
same size with the color I wanted and then animating it from the screen up. However, this is not a very elegant way to do it. Is there a better way to do this? Any moments would be really appreciated. Thank!
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Try the following:
CALayer *layer = [CALayer layer];
layer.frame = CGRectMake(0, self.view.bounds.size.height, self.view.bounds.size.width, self.view.bounds.size.height);
layer.backgroundColor = [UIColor blueColor].CGColor;
[self.view.layer addSublayer:layer];
CABasicAnimation *animation = [CABasicAnimation animation];
animation.keyPath = @"position.y";
animation.byValue = @(-self.view.bounds.size.height);
animation.duration = 1;
animation.fillMode = kCAFillModeForwards;
animation.removedOnCompletion = NO;
[layer addAnimation:animation forKey:@"Splash"];
You may try:
[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:2.0];
[UIView setAnimationTransition:UIViewAnimationTransitionCurlUp
forView:self.view cache:NO];
self.view.layer.backgroundColor = [UIColor blueColor].CGColor;
[UIView commitAnimations];
I also have another suggestion that makes the transition smooth:
[UIView animateWithDuration:2.0 animations:^{
self.view.layer.backgroundColor = [UIColor blueColor].CGColor;
} completion:nil];
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You can:
- Use a different UIView as an intermediate in your animation as you mentioned. its not that elegant, but it works and is simple.
- Work with CALayer , if you find it, you can find many simple examples, for example from Ray Wenderlich which I really like.
UPDATE
I took over this effect using CAShapeLayer and also created the effect using UIView animation. Here are the snippets, their comments and no changes:
UIView
- (void)changeColorWithFillingAnimation {
//we create a view that will increase in size from top to bottom, thats why it starts with these frame parameters
UIView *fillingView = [[UIView alloc] initWithFrame:CGRectMake(0, self.view.bounds.size.height - 1, self.view.bounds.size.width, 1)];
//set the color we want to change to
fillingView.backgroundColor = [UIColor blueColor];
//add it to the view we want to change the color
[self.view addSubview:fillingView];
[UIView animateWithDuration:2.0 animations:^{
//this will make so the view animates up, since its animating the frame to the target view size
fillingView.frame = self.view.bounds;
} completion:^(BOOL finished) {
//set the color we want and then disappear with the filling view.
self.view.backgroundColor = [UIColor blueColor];
[fillingView removeFromSuperview];
}];
}
CAShapeLayer + CABasicAnimation + CATransition
- (void)changeColorWithShapeLayer {
//create the initial and the final path.
UIBezierPath *fromPath = [UIBezierPath bezierPathWithRect:CGRectMake(0, self.view.bounds.size.height - 1, self.view.bounds.size.width, 1)];
UIBezierPath *toPath = [UIBezierPath bezierPathWithRect:CGRectMake(0, 0, self.view.bounds.size.width, self.view.bounds.size.height)];
//create the shape layer that will be animated
CAShapeLayer *fillingShape = [CAShapeLayer layer];
fillingShape.path = fromPath.CGPath;
fillingShape.fillColor = [UIColor blueColor].CGColor;
//create the animation for the shape layer
CABasicAnimation *animatedFill = [CABasicAnimation animationWithKeyPath:@"path"];
animatedFill.duration = 2.0f;
animatedFill.fromValue = (id)fromPath.CGPath;
animatedFill.toValue = (id)toPath.CGPath;
//using CATransaction like this we can set a completion block
[CATransaction begin];
[CATransaction setCompletionBlock:^{
//when the animation ends, we want to set the proper color itself!
self.view.backgroundColor = [UIColor blueColor];
}];
//add the animation to the shape layer, then add the shape layer as a sublayer on the view changing color
[fillingShape addAnimation:animatedFill forKey:@"path"];
[self.view.layer addSublayer:fillingShape];
[CATransaction commit];
}
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