Question

I use the following code to get a NSString from a NSDictionary and then cast it into NSUrl:

NSURL * url = [NSURL URLWithString:[self.item objectForKey:@"website"]];

The NSDictionary self.item comes from a web server and it’s correctly filled using JSON data. All the other objects inside the NSDictionary work perfectly fine.

But sometimes the web server passes a website url with the text “null” because the object has no website filled in. From debugging i learned that the NSURL object can contain a url with the text “null”. But how do i prevent this, or how can i write an if statement that checks this?

I tried the following:

NSString * niks = [eventUrl absoluteString];
if(niks == @"null")
{
    UIAlertView *message = [[UIAlertView alloc] initWithTitle:@"Event" message:@"Event heeft geen website" delegate:nil cancelButtonTitle:@"Oke" otherButtonTitles:@"Oke", nil];
    [message show];
}
else
{
    [webView loadRequest:[NSURLRequest requestWithURL:eventUrl]];
    NSLog(@"%@",eventUrl);
}

But this doesn’t work, it always passes the url directly to the webview. Can someone set me in the right direction?

Answer 1

Your comparison;

if(niks == @"null")

only compares if the pointers are equal (i.e. if the two are the same string object instance). Since one is a constant and the other is created dynamically from JSON fetched from the server, it’s very unlikely.

To compare the content of two strings, you should instead do;

if([niks isEqualToString:@"null"])

For the link thirsty, here is the [NSString isEqualToString:] documentation.