Question

How do i check if the UIImageView did fail to load the image ?

I have a UIImageView loading an image from URL like so:

      [MyImageView setImage:[UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://exampleUrl.com/images/the_image.png"]]]];

but if the image for some reason is not available i want to load an alternative image.

How would i approach this problem ? Can i add some kind of observer ?

Alternatively can i check when the ImageView did finish loading the image to check if the image is nil ?

Thanks !

Answer 1

You are making a synchronous request on main thread and not even checking error conditions like if it fails or network connection times out.

You can use this instead:

[NSURLConnection sendAsynchronousRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://exampleUrl.com/images/the_image.png"]] queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse* response, NSData* data, NSError* error){

if(error)
{
  // Error Downloading image data
}
else
{
  [MyImageView setImage:[UIImage imageWithData:data]];
}
}];

Using Asychronous url load using NSURLConnection. When connection has finished downloading data or error occured it notifies via connection handler block.