I am trying to implement the SVProgressHUD activity indicator. I copied the classes to my project and added the following code to my appDelegate but can't figure out why it crashes. 

I get they following error and am not sure where to look to fix it: 

```
Undefined symbols for architecture i386:
"_OBJC_CLASS_$_SVProgressHUD", referenced from:
objc-class-ref in QuotesAppDelegate.o
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation) 

```

Here is the code: 

```
#import "SVProgressHUD.h"

@implementation QuotesAppDelegate

- (void)startLoading
{
    //call this in your app delegate instead of setting window.rootViewController to your main view controller
    //you can show a UIActivityIndiocatorView here or something if you like
    [SVProgressHUD show];
    [self performSelectorInBackground:@selector(loadInBackground) withObject:nil];
}

- (void)loadInBackground
{
    //do your loading here
    //this is in the background, so don't try to access any UI elements
    [self populateFromDatabase];

    [SVProgressHUD dismiss];

    [self performSelectorOnMainThread:@selector(finishedLoading) withObject:nil waitUntilDone:NO];
}

- (void)finishedLoading
{
    //back on the main thread now, it's safe to show your view controller
    [window addSubview:[navigationController view]];
    [window makeKeyAndVisible];
}

- (void)applicationDidFinishLaunching:(UIApplication *)application {

[self copyDatabaseIfNeeded];

    [self startLoading];

}

```