Open Another App
NSURL *appURL = [NSURL URLWithString:@"someappname://"];
if ([[UIApplication sharedApplication] canOpenURL:appURL])
{
[[UIApplication sharedApplication] openURL:appURL];
}
else
{
NSURL *appStoreURL = [NSURL URLWithString:@"http://itunes.apple.com/gb/app/someappname/id123456789?mt=8#"];
[[UIApplication sharedApplication] openURL:appStoreURL];
}