Tips to Loading image from a URL to UIImage object
Load image pointed by URL, for example, http://mycodetips.com/images/image0.jpg, using NSURL, NSURLRequest, and NSURLConnection
NSURLConnection *conn = [[NSURLConnection alloc] initWithRequest:
[NSURLRequest requestWithURL:
[NSURL URLWithString:@“http://mycodetips.com/images/image0.jpg”]] delegate:self];
Implement delegate methods of NSURLConnection
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
NSMutableData object can be used store data fragment whenever it is received
self.imageData = [NSMutableData data];
…
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
[self.imagedata appendData:data];
}
Sample code
- (void)startDownload
{
self.imageData = [NSMutableData data];
// alloc+init and start an NSURLConnection; release on completion/failure
NSURLConnection *conn = [[NSURLConnection alloc] initWithRequest:
[NSURLRequest requestWithURL:
[NSURL URLWithString:imageURLString]] delegate:self];
self.imageConnection = conn;
[conn release];
}
- (void)cancelDownload
{
[self.imageConnection cancel];
self.imageConnection = nil;
self.imageData = nil;
}
#pragma mark -
#pragma mark Download support (NSURLConnectionDelegate)
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
[self.activeDownload appendData:data];
}- (
void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
// Clear the activeDownload property to allow later attempts
self.imageData = nil;
// Release the connection now that it’s finished
self.imageConnection = nil;
}- (
void)connectionDidFinishLoading:(NSURLConnection *)connection
{
// Set appIcon and clear temporary data/image
UIImage *image = [[UIImage alloc] initWithData:self.imageData];
// Now we have loaded image in ‘image’
// DO WHATEVER WE WAN WITH ‘image’
// call our delegate and tell it that our icon is ready for display
[delegate appImageDidLoad: image];
[image autorelease];
// clean-up
self.imageData = nil;
// Release the connection now that it’s finished
self.imageConnection = nil;
}
