Loading image from url to uiimageview make iphone app slower performance

Question

am developing an rss feed app for iphone, in that i have a tableview where all feed titles will show when user click on title a detail view will show with title, description and image but am facing problem with performance since the application taking time to load image in UIImageView since the image is coming from image url below is my code.

NSURL *url = [NSURL URLWithString:imageURL];
NSData *data = [NSData dataWithContentsOfURL:url];
UIImageView *subview = [[UIImageView alloc] initWithFrame:CGRectMake(110,10,100,80)];
[subview setImage:[UIImage imageWithData:data]]; 
[cell addSubview:subview];
[subview release];

in this code imageurl is coming from rss and processing to UIImageView to show image. if i remove this specific code the performance is good since all data is text.

so how can i get image from url and display to UIImageView control very quickly without losing performance or show activity indicator until image load completly separately. please help me for this.

Answer 1

Never perform network calls on the main thread. Apple provides a helpful example app for this. See the LazyTableImages sample app for the proper way to load images in the background.

Answer 2

Hi you can also use a third party Class for you problem called AsyncImageView

Or you can create your own class that have NSURLConnectionDelegate that downloads an image

These solutions can also solve your problems when the UI is locking because of synchronous url request.

Answer 3

have a look at here

[DLImageLoader loadImageFromURL:imageURL
                          completed:^(NSError *error, NSData *imgData) {
                              imageView.image = [UIImage imageWithData:imgData];
                              [imageView setContentMode:UIViewContentModeCenter];

                          }];

Answer 4

you can try this one,

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,0), ^(void) {
    [self loadImage];
});

-(void) loadImage
{
    NSURL *url = [NSURL URLWithString:imageURL];
    NSData *data = [NSData dataWithContentsOfURL:url];
    UIImageView *subview = [[UIImageView alloc] initWithFrame:CGRectMake(110,10,100,80)];
    [subview setImage:[UIImage imageWithData:data]];
    [cell addSubview:subview];
    [subview release];

}

thanks

Answer 5

you can try this

//in .h file

 IBOutlet UIImageView *imgTest;

-(IBAction)buttonTapped:(id)sender;
-(void)LoadImage:(NSString *) irlString;
-(void)setImage:(NSData *) imgData;

//in .m file write the following code:

-(IBAction)buttonTapped:(id)sender
{
    [self performSelectorOnMainThread:@selector(LoadImage:) withObject:@"http://www.google.com/images/errors/logo_sm.gif" waitUntilDone:NO];
}

-(void)LoadImage:(NSString *) urlString
{
    NSURL *imgURL=[NSURL URLWithString:urlString];
    NSData *imgData=[NSData dataWithContentsOfURL:imgURL];
    [self performSelectorInBackground:@selector(setImage:) withObject:imgData];
}

-(void)setImage:(NSData *) imgData;
{
    imgTest.image=[UIImage imageWithData:imgData];
}

hope this will help you.