Download using NSURLConnection - ios

Question

I have a UIImageView that is displaying an image using a URL, I have a download button that brings up a UIActionSheet which will then download the file using the URL i want to know how to do the coding for the download part of it using NSURLConnection.
- (IBAction)DownloadClick:(id)sender {
UIActionSheet *Action = [[UIActionSheet alloc]
initWithTitle:#"Options"
delegate:self
cancelButtonTitle:#"Cancel"
destructiveButtonTitle:nil
otherButtonTitles:#"Download", nil];
[Action showInView:self.view];
}
-(void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex {
if (buttonIndex == 0) { //The Download code will go here This is where i need ur help
}
The Url is saved in a string named "Url".

Answer 1

I don't think you tried Google for this. Anyway, here is your code and don't forget to add NSURLConnectionDataDelegate,
-(void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex
{
if (buttonIndex == 0) { //The Download code will go here This is where i need ur help
//-------------------------------------------------------
NSURL *url = [NSURL URLWithString:#"your_data_url"];
NSURLRequest *request = [NSURLRequest requestWithURL:url
cachePolicy:NSURLRequestUseProtocolCachePolicy
timeoutInterval:60.0];
NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
if (connection) {
NSLog(#"succeed...");
} else {
NSLog(#"Failed...");
}
//-------------------------------------------------------------------
}
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
}

Answer 2

Make use of asynchronous request for image download. It can also help you identify errors, if any during image downloading.
NSURL* url = [NSURL URLWithString:#"http://imageAddress.com"];
NSURLRequest* request = [NSURLRequest requestWithURL:url];
[NSURLConnection sendAsynchronousRequest:request
queue:[NSOperationQueue mainQueue]
completionHandler:^(NSURLResponse * response,
NSData * data,
NSError * error) {
if (!error){
UIImage* image = [[UIImage alloc] initWithData:data];
// do whatever you want with image
}
}];

Answer 3

If you need synchronous download you can try this code:
NSURL *imageUrl = [NSURL URLWithString:#"http://site.com/imageName.ext"];
NSData *imageData = [NSData dataWithContentsOfURL:imageUrl];
UIImage *image = [[UIImage alloc] initWithData:imageData];
Now you have an image that you can use.
If you need an asynchronous request I suggest you to read the NSURLConnectionDataDelegate, that helps you handle the download of the file.