Animated background in iOS - objective-c

Question

I want to animate my background after a view got loaded in my iOS application. This works with solid colors, but I'm not able to let it work using background images. This is my code:
- (void)viewDidLoad
{
[super viewDidLoad];
[UIView animateWithDuration:5.0 animations:^{
self.view.backgroundColor = [[UIColor alloc] initWithPatternImage:[UIImage imageNamed:#"background.png"]];
self.view.backgroundColor = [[UIColor alloc] initWithPatternImage:[UIImage imageNamed:#"background_dark.png"]];
}];
[UIView commitAnimations];
}
Does anyone know the correct way to do this?
Thanks

Answer 1

You animate things like this:
view.backgroundColor = INITIAL COLOR
[UIView animateWithDuration:5.0 animations:^{
view.backgroundColor = FINAL COLOR
}];
The animate method animates the change from the current state to whatever you set up in the animation block. The animation block is not a list of steps.
Therefore, I think what you want is this:
self.view.backgroundColor = [[UIColor alloc] initWithPatternImage:[UIImage imageNamed:#"background.png"]];
[UIView animateWithDuration:5.0 animations:^{
self.view.backgroundColor = [[UIColor alloc] initWithPatternImage:[UIImage imageNamed:#"background_dark.png"]];
}];
Also, do NOT call commitAnimations afterward, that's only if you're using the old-style beginAnimations method. Read the documentation, and don't just call methods to see if they work.

Answer 2

Not all properties can be animated like this. It is very likely that a background image is one of them. What you can do is have a second view on top with the new image and animate its alpha from 0 to 1.

Answer 3

Ty this:
[UIView animateWithDuration:5.0 animations:^{
self.view.backgroundColor = [[UIColor alloc] initWithPatternImage:[UIImage imageNamed:#"background.png"]];
} completion:^(BOOL finished)
{
self.view.backgroundColor = [[UIColor alloc] initWithPatternImage:[UIImage imageNamed:#"background_dark.png"]];
}];