Only Visible View Animation - ios

Question

I have the following implementation. Each view has animation, but my problem is that all animation run no matter visible or invisible.I only want the currently seen(active) view animation works, other view animation are disabled unless until user scrolls it.
- (UIView *)carousel:(iCarousel *)carousel viewForItemAtIndex:(NSInteger)index reusingView:(UIView *)view{
if (view == nil){
if(index==0)
{
view=[[UIImageView alloc]initWithFrame:CGRectMake(30, 30, 600, 600)];
((UIImageView *)view).animationImages=[NSArray arrayWithObjects:[UIImage imageNamed:#"Walking-1.png"],
[UIImage imageNamed:#"Walking-2.png"],
[UIImage imageNamed:#"Walking-3.png"],
[UIImage imageNamed:#"Walking-4.png"],
[UIImage imageNamed:#"Walking-5.png"],nil];
((UIImageView *)view).animationDuration = 1.5;
[((UIImageView *)view) startAnimating];
}
else if(index==1)
{
view=[[UIImageView alloc]initWithFrame:CGRectMake(30, 30, 600, 600)];
((UIImageView *)view).animationImages=[NSArray arrayWithObjects:[UIImage imageNamed:#"Biking-1.png"],
[UIImage imageNamed:#"Biking-2.png"],
[UIImage imageNamed:#"Biking-3.png"],
[UIImage imageNamed:#"Biking-4.png"],
[UIImage imageNamed:#"Biking-5.png"],nil];
((UIImageView *)view).animationDuration = 1.5;
[((UIImageView *)view) startAnimating];
}
view.contentMode = UIViewContentModeCenter;
[view.layer setMasksToBounds:YES];
}
return view;
}

Answer 1

iCarouselDelegate has a method carouselCurrentItemIndexDidChange you should do stop/start your animations there, but not in data source method. So save all your animations into array with an index equal to an item index and use currentItemIndex property of carousel in carouselCurrentItemIndexDidChange to start appropriate animation. You will need to store previous index somewhere in your class, to be able to stop previous animation, before start new one.
#import UIKit;
#interface CarouselController: UIViewController
#property(nonatomic, readonly) NSArray *carouselItems;
#property(nonatomic, assign) NSInteger lastItemIndex;
#end
#implementation CarouselController
- (instancetype)init {
self = [super init];
if (self) {
[self initializeCarouselContent];
}
return self;
}
- (instancetype)initWithCoder:(NSCoder *)aDecoder {
self = [super initWithCoder:aDecoder];
if (self) {
[self initializeCarouselContent];
}
return self;
}
- (instancetype)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
[self initializeCarouselContent];
}
return self;
}
- (void)initializeCarouselContent {
self.lastItemIndex = 0;
_carouselItems = #[[CarouselController activityAnimationView: #"Walking"], [CarouselController activityAnimationView: #"Biking"]];
UIImageView *currentAnimation = self.carouselItems[self.lastItemIndex];
[currentAnimation startAnimating];
}
+ (UIImageView *)activityAnimationView:(NSString *)activity {
UIImageView *result = [[UIImageView alloc]initWithFrame:CGRectMake(30, 30, 600, 600)];
NSMutableArray *activityImages = [[NSMutableArray alloc] init];
for (int activityIndex = 1; activityIndex <= 5; activityIndex ++) {
NSString *imageName = [NSString stringWithFormat:#"%#-%i.png", activity, activityIndex];
[activityImages addObject:[UIImage imageNamed:imageName]];
}
result.animationImages = activityImages;
result.animationDuration = 1.5;
result.contentMode = UIViewContentModeCenter;
[result.layer setMasksToBounds:YES];
return result;
}
- (NSInteger)numberOfItemsInCarousel:(iCarousel *)carousel {
return [_carouselItems count];
}
- (UIView *)carousel:(iCarousel *)carousel viewForItemAtIndex:(NSInteger)index reusingView:(UIView *) view{
if (view == nil){
view = self.carouselItems[index];
}
return view;
}
- (void)carouselCurrentItemIndexDidChange:(iCarousel *)carousel {
if (carousel.currentItemIndex != self.lastItemIndex) {
UIImageView *currentAnimation = self.carouselItems[self.lastItemIndex];
[currentAnimation stopAnimating];
self.lastItemIndex = carousel.currentItemIndex;
currentAnimation = self.carouselItems[self.lastItemIndex];
[currentAnimation startAnimating];
}
}
#end