Fade Effect when Scrolling - ios

Question

I would like to add the fade effect when user scroll my galleryViewController which fetch the data from the server. I could not able to implement the fade effect to my scrollViewController.
Code:
#import "GrillGalleryCollectionViewController.h"
#import "AFNetworking.h"
#interface GrillGalleryCollectionViewController ()
#end
#implementation GrillGalleryCollectionViewController
#synthesize scrollView,pageControl, colors;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
// colors=[[NSArray alloc]init];
colors = [[NSArray alloc] init];;
[self getActiveOffers];
// NSArray *colors = [NSArray arrayWithObjects:[UIColor redColor], [UIColor greenColor], [UIColor blueColor], nil];
}
- (void)scrollViewDidScroll:(UIScrollView *)sender {
// Update the page when more than 50% of the previous/next page is visible
CGFloat pageWidth = self.scrollView.frame.size.width;
int page = floor((self.scrollView.contentOffset.x - pageWidth / 2) / pageWidth) + 1;
self.pageControl.currentPage = page;
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
/*
#pragma mark - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
// Get the new view controller using [segue destinationViewController].
// Pass the selected object to the new view controller.
}
*/
- (IBAction)changePage:(id)sender {
CGRect frame;
frame.origin.x = self.scrollView.frame.size.width * self.pageControl.currentPage;
frame.origin.y = 0;
frame.size = self.scrollView.frame.size;
[self.scrollView scrollRectToVisible:frame animated:YES];
}
- (IBAction)backBtnPressed:(id)sender {
[self.navigationController popViewControllerAnimated:YES];
}
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
pageControlBeingUsed = NO;
}
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
pageControlBeingUsed = NO;
}
- (void) getActiveOffers {
NSString *string = #"http://znadesign.com/appcenter/api.php?function=get_gallery&customer_id=1";
NSLog(#"%#", string);
NSURL *url = [NSURL URLWithString:string];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
operation.responseSerializer = [AFJSONResponseSerializer serializer];
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
int total_count = (int)[[responseObject valueForKey:#"total_count"] integerValue];
if (total_count > 0) {
NSMutableArray *array = [[NSMutableArray alloc] initWithCapacity:total_count];
for (int i = 1; i <= total_count; i++) {
NSString *key = [NSString stringWithFormat:#"%i", i];
id object = [responseObject objectForKey:key];
[array addObject:object];
}
colors = [NSArray arrayWithArray:array];
[self setSizeSliding];
// [myTableView reloadData];
}
else
{
UIAlertView *alertView2 = [[UIAlertView alloc] initWithTitle:#"There is no internet connection."
message:nil
delegate:nil
cancelButtonTitle:#"OK"
otherButtonTitles:nil];
[alertView2 show];
}
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
// 4
UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:#"There is no internet connection."
message:[error localizedDescription]
delegate:nil
cancelButtonTitle:#"Ok"
otherButtonTitles:nil];
[alertView show];
}];
// 5
[operation start];
}
-(void) setSizeSliding
{
for (int i = 0; i < colors.count; i++) {
CGRect frame;
frame.origin.x = self.scrollView.frame.size.width * i;
frame.origin.y = 0;
frame.size = self.scrollView.frame.size;
// UIView *subview = [[UIView alloc] initWithFrame:frame];
// subview.backgroundColor = [colors objectAtIndex:i];
// NSString *imageURLString=[[offersArray objectAtIndex:indexPath.row] valueForKey:#"picture"];
NSString*slidingImage = [[colors objectAtIndex:i] valueForKey:#"picture"];
NSURL *url = [NSURL URLWithString:slidingImage];
NSData *data = [[NSData alloc] initWithContentsOfURL:url];
UIImage *tmpImage = [[UIImage alloc] initWithData:data];
UIImageView *slidingImageView = [[UIImageView alloc]initWithFrame:frame];
slidingImageView.image = tmpImage;
[self.scrollView addSubview:slidingImageView];
}
self.scrollView.contentSize = CGSizeMake(self.scrollView.frame.size.width * colors.count, self.scrollView.frame.size.height);
}
#end
I want to implement the similar fade effect as it is listed below:
[UIView animateWithDuration:2
animations:^{imageView.alpha = 0.0;}
completion:^(BOOL finished){ [imageView removeFromSuperview];}];

Answer 1

You have the code Can you adding the below code and try whether the animation works..
-(void) animateSubViews
{
int buffer = 10;
CGRect frame = CGRectMake((self.pageControl.currentPage * self.scrollView.frame.size.width)-buffer, 0, self.scrollView.frame.size.width + buffer, self.scrollView.frame.size.height);
[UIView animateWithDuration:0.4
animations:^{
for (UIView *view in self.scrollView.subviews)
{
if (CGRectContainsRect(frame, view.frame))
{
[view setAlpha:1.0];
}
else
{
[view setAlpha:0.0];
}
}
}];
}
Try calling this method from ScrollView did scroll and change page.
- (IBAction)changePage:(id)sender {
CGRect frame;
frame.origin.x = self.scrollView.frame.size.width * self.pageControl.currentPage;
frame.origin.y = 0;
frame.size = self.scrollView.frame.size;
[self.scrollView scrollRectToVisible:frame animated:YES];
//Call to animate
[self animateSubViews];
}
- (void)scrollViewDidScroll:(UIScrollView *)sender
{
// Update the page when more than 50% of the previous/next page is visible
CGFloat pageWidth = self.scrollView.frame.size.width;
int page = floor((self.scrollView.contentOffset.x - pageWidth / 2) / pageWidth) + 1;
self.pageControl.currentPage = page;
//Call to animate
[self animateSubViews];
}