How to show Alert when UIApplication is not able to open URL? - ios

Question

This method opens up the url in Safari when the website string is not null and it is atleast of length 3. But when I have supplierWebsite=#"www.heritage.com", nothing happens. I know that heritage.com is not valid website and so it is not activating in UIApplication. I would like to display atleast a pop up that would tell user that website is not available. Is there any way i can show Alertview telling that website is not available.
- (IBAction)doWebOpen:(UIButton *)sender {
if (self.provider.supplierWebSite && [self.provider.supplierWebSite length] > 3) {
NSString *urlString = [self.provider supplierWebSite];
NSURL *url = [NSURL URLWithString:urlString];
[[UIApplication sharedApplication] openURL:url];
}else {
NSError *err = [NSError errorWithDomain:#"com.cantopenweb" code:509 andDescription:#"This supplier does not have a website."];
[self showErrorAlert:err];
}}

Answer 1

You could use canOpenURL method,
[[UIApplication sharedApplication] canOpenURL:[NSURL
URLWithString:#"your website"]];
The method returns a BOOL, so check that for YES or NO.
If YES, it CAN else NO.

Answer 2

Just use canOpenURL of UIApplication class, like:
if([[UIApplication sharedApplication] canOpenURL:url])
{
[[UIApplication sharedApplication] openURL:url];
}
else
{
//show alert
}
canOpenURL:
Returns whether an application can open a given URL resource.
- (BOOL)canOpenURL:(NSURL *)url
Parameters
url
A URL object that identifies a given resource. The URL’s scheme—possibly a custom scheme—identifies which application can
handle the URL.
Return Value
NO if no application is available that will accept the URL; otherwise,
returns YES. Discussion
This method guarantees that that if openURL: is called, another
application will be launched to handle it. It does not guarantee that
the full URL is valid. Availability
Available in iOS 3.0 and later.
Declared In UIApplication.h