How to make animation when changing UIImageView - iphone

Question

I wrote this code and made 2 buttons, next and back, to display a picture in an NSMutubleArray using an UIImageView.
-(IBAction) pictureNext:(id)sender;
{
if (pictureIndice==[promMUAraay count])
{
pictureIndice=0;
}
NSLog(#"indice : %d ",pictureIndice);
Promotion *prom = [[Promotion alloc]init];
prom =[promMUAraay objectAtIndex:pictureIndice];
promotionPicture.image = [UIImage imageWithData:prom.pPicture];
//promLabel.text=prom.pName;
NSLog(#"label : %#",prom.pName);
pictureIndice++;
}
-(IBAction) pictureBack:(id)sender;
{
if (pictureIndice==[promMUAraay count])
{
pictureIndice=0;
}
NSLog(#"indice : %d ",pictureIndice);
Promotion *prom = [[Promotion alloc]init];
prom =[promMUAraay objectAtIndex:pictureIndice];
promotionPicture.image = [UIImage imageWithData:prom.pPicture];
//promLabel.text=prom.pName;
if (pictureIndice==0)
{
pictureIndice=[promMUAraay count];
}
pictureIndice--;
}
This works, but is it possible to make a little animation when changing image?

Answer 1

There are a lot of animation options to choose from. Since you have a single UIImageView object, here is a "fade out/in" example (warning: not tested):
-(void)fadeView:(UIView *)thisView fadeOut:(BOOL)fadeOut {
// self.ReviewViewController.view.alpha = 1;
[UIView beginAnimations:#"fadeOut" context:nil];
[UIView setAnimationDuration:0.3];
[UIView setAnimationCurve:UIViewAnimationCurveLinear];
if (fadeOut) {
thisView.alpha = 0;
} else {
thisView.alpha = 1;
}
[UIView commitAnimations];
}
Then in your pictureNext and pictureBack you can change the line:
promotionPicture.image = [UIImage imageWithData:prom.pPicture];
to these 3 lines:
[self fadeView:promotionPicture fadeOut:YES];
promotionPicture.image = [UIImage imageWithData:prom.pPicture];
[self fadeView:promotionPicture fadeOut:NO];
Side note:
You could combine your pictureNext and pictureBack by having both buttons call the same selector and determining if you sender is the back or forward button.
-(IBAction)pictureMove:(id)sender {
if (sender == yourNextButton) {
//do next index math here
} else if (sender == yourBackButton) {
//do back index math here
}
.
.
.
//you image change code goes here
.
.
.
}