Activity Indicator while loading images inside UIScrollView - cocoa-touch

Question

I have UIScrollView that contains images from the server.
I should put Activity Indicator while the image is currently loading.
UIScrollView contains dynamic number of images from the server.
May I know how can I add activity indicators on each page while the image is loading and remove once image is loaded.
Here's my code to retrieve images:
NSDictionary *items = [NSDictionary dictionaryWithObject:dictInfo forKey:#"images"];
imageList = [items objectForKey:#"images"];
NSArray *img = [imageList objectForKey:#"list"];
NSInteger imgCount = [img count];
buttonArray = [[NSMutableArray alloc] init];
for (int i=0; i<imgCount; i++) {
NSDictionary *imgDict = [img objectAtIndex:i];
// REQUEST FOR IMAGES
NSString *imgPath = [imgDict objectForKey:#"image_slot"];
NSString *imgURL = imgPath;
__block ASIHTTPRequest *requestImage = [ASIHTTPRequest requestWithURL:[NSURL URLWithString:imgURL]];
[requestImage setCompletionBlock:^{
imgView = [UIImage imageWithData:[requestImage responseData]];
if (imgURL.length) {
[pendingRequests removeObjectForKey:imgURL];
}
scrollView.userInteractionEnabled = YES;
scrollView.exclusiveTouch = YES;
scrollView.canCancelContentTouches = YES;
scrollView.delaysContentTouches = YES;
scrollView.bounces = NO;
CGRect frame;
frame.origin.x = self.scrollView.frame.size.width * i;
frame.origin.y = 0;
frame.size = self.scrollView.frame.size;
SWTUIButton *imgBtn = [[SWTUIButton alloc] initWithFrame:frame];
imgBtn.url = [requestImage.userInfo objectForKey:#"rURL"];
[imgBtn setImage:imgView forState:UIControlStateNormal];
imgBtn.backgroundColor = [UIColor clearColor];
[imgBtn addTarget:self action:#selector(buttonpushed:) forControlEvents:UIControlEventTouchUpInside];
[scrollView addSubview:imgBtn];
[buttonArray addObject:imgBtn];
[imgBtn release];
self.scrollView.contentSize = CGSizeMake(self.scrollView.frame.size.width * img.count, self.scrollView.frame.size.height);
}];

Answer 1

I highly suggest you use NINetworkImageView from https://github.com/jverkoey/nimbus project.
It's very light and useful.
It has a delegate method to let you know when an image is loaded.
What you basically need to do is:
1. create an NINetworkImageView for each page, just like you do with UIImageView, and call set
NINetworkImageView* networkImageView = [[[NINetworkImageView alloc] initWithImage:initialImage]
autorelease];
networkImageView.delegate = self;
networkImageView.contentMode = UIViewContentModeCenter;
[networkImageView setPathToNetworkImage:
#"http://farm3.static.flickr.com/2484/3929945380_deef6f4962_z.jpg"
forDisplaySize: CGSizeMake(kImageDimensions, kImageDimensions)];
https://github.com/jverkoey/nimbus/tree/master/examples/photos/NetworkPhotoAlbums
the add the indicator to the networkImageView as a subview.
implement the delegate as follows:
-(void)networkImageView:(NINetworkImageView *)imageView didLoadImage:(UIImage *)image {
[imageView removeAllSubviews];
}
the end result would be a much smaller code for doing the same thing.