App Crashing During Signing Up New Users Part 2 - PFUser Lesson

Just completed the lesson in the subject line which goes over how to setup new sign-ups in parse.

I completed the video and followed along with the tutorial. My code shows no bugs and successfully launches.

When I fill out the sign up for and hit submit, the app crashes.

Here's the error:

2014-06-04 00:04:11.485 Ribbit[925:60b] -[NSCFCharacterSet length]: unrecognized selector sent to instance 0x10a711840 2014-06-04 00:04:11.490 Ribbit[925:60b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSCFCharacterSet length]: unrecognized selector sent to instance 0x10a711840' *** First throw call stack: ( 0 CoreFoundation 0x0000000102828495 exceptionPreprocess + 165 1 libobjc.A.dylib 0x000000010258799e objc_exception_throw + 43 2 CoreFoundation 0x00000001028b965d -[NSObject(NSObject) doesNotRecognizeSelector:] + 205 3 CoreFoundation 0x0000000102819d8d ___forwarding_ + 973 4 CoreFoundation 0x0000000102819938 CF_forwarding_prep_0 + 120 5 Foundation 0x000000010214c6e2 -[NSString stringByAppendingString:] + 130 6 Ribbit 0x0000000100002797 -[SignupViewController signup:] + 327 7 UIKit 0x0000000101135f06 -[UIApplication sendAction:to:from:forEvent:] + 80 8 UIKit 0x0000000101135eb4 -[UIApplication sendAction:toTarget:fromSender:forEvent:] + 17 9 UIKit 0x0000000101212880 -[UIControl _sendActionsForEvents:withEvent:] + 203 10 UIKit 0x0000000101211dc0 -[UIControl touchesEnded:withEvent:] + 530 11 UIKit 0x000000010116cd05 -[UIWindow _sendTouchesForEvent:] + 701 12 UIKit 0x000000010116d6e4 -[UIWindow sendEvent:] + 925 13 UIKit 0x000000010114529a -[UIApplication sendEvent:] + 211 14 UIKit 0x0000000101132aed _UIApplicationHandleEventQueue + 9579 15 CoreFoundation 0x00000001027b7d21 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION_ + 17 16 CoreFoundation 0x00000001027b75f2 __CFRunLoopDoSources0 + 242 17 CoreFoundation 0x00000001027d346f __CFRunLoopRun + 767 18 CoreFoundation 0x00000001027d2d83 CFRunLoopRunSpecific + 467 19 GraphicsServices 0x0000000103981f04 GSEventRunModal + 161 20 UIKit 0x0000000101134e33 UIApplicationMain + 1010 21 Ribbit 0x00000001000024b3 main + 115 22 libdyld.dylib 0x00000001031095fd start + 1 23 ??? 0x0000000000000001 0x0 + 1 ) libc++abi.dylib: terminating with uncaught exception of type NSException

And here's my code starting at the IBAction:

- (IBAction)signup:(id)sender {

NSString *username = [self.usernameField.text stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
NSString *password = [self.passwordField.text stringByAppendingString:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
NSString *email = [self.emailField.text stringByAppendingString:[NSCharacterSet whitespaceAndNewlineCharacterSet]];

if ([username length] == 0 || [password length] == 0 || [email length] == 0) {
UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Oops" message:@"Make sure you enter a username, password, and email address!" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];

[alertView show];

}

else {
PFUser *newUser = [PFUser user];

newUser.username = username;
newUser.password = password;
newUser.email = email;

[newUser signUpInBackgroundWithBlock:^(BOOL succeeded, NSError *error) {

 if (error) {
UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Sorry" message:[error.userInfo objectForKey:@"error"] delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];

[alertView show];

}

else {
 [self.navigationController popToRootViewControllerAnimated:YES];
}
 }];
}
}

@end

Thanks for your time,

Ryan