Terminating App due to uncaught exception iOS - ios

Question

using Parse and just upgraded to XCode 6 (installed Yosemite). My app worked fine until then, now it doesn't even load the first screen (login view controller).
Here's the error message:
2014-10-21 00:30:34.754 Hi App[393:143637] *** Terminating app due to uncaught exception
'NSInvalidArgumentException', reason: 'Cannot do a comparison query for type: (null)'
*** First throw call stack:
(0x25e03e3f 0x334b1c8b 0x25e03d85 0x8d173 0x785fd 0x5fee3 0x292b785f 0x2934b51f 0x2934aff3
0x2934ad5d
0x2934acf1 0x2929f677 0x28cc7ccd 0x28cc36b5 0x28cc353d 0x28cc2f21 0x28cc2d25 0x29503395 0x2950413d
0x2950e549 0x29502557 0x2c5450e9 0x25dca5b5 0x25dc9879 0x25dc83b3 0x25d16621 0x25d16433
0x2930656f
0x29301359 0x5d1b5 0x33a31aaf)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)
Here's my loginviewcontroller.m:
- (void)viewDidLoad
{
[super viewDidLoad];
self.navigationItem.hidesBackButton = YES;
}
- (IBAction)login:(id)sender {
NSString *username = [self.enterUsername.text stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
NSString *password = [self.enterPassword.text stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
if ([username length] == 0 || [password length] == 0) {
UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:#"Oops!"
message:#"Please enter a username, password."
delegate:nil cancelButtonTitle:#"OK" otherButtonTitles:nil];
[alertView show];
}
[PFUser logInWithUsernameInBackground:username password:password block:^(PFUser *user, 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];
}
}];
}

Answer 1

I would first double check to make sure that username and password are not nil. Of course I see you have a check to make sure password and username length is not equal to 0.
The problem with this check is that you are checking, displaying a UIAlert and then the rest of the code is still being executed.
Either return to exit the function or stick the rest of the execution in an else statement.
Try this out:
if ([username length] == 0 || [password length] == 0) {
UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:#"Oops!"
message:#"Please enter a username, password."
delegate:nil cancelButtonTitle:#"OK" otherButtonTitles:nil];
[alertView show];
return;
}

Answer 2

I technically solved it by rebuilding part of the project. I don't know what the problem was, but it probably has something to do with the old files mixing with iOS 8 (not sure what made it fail like that). I compiled the new project in iPhone 5 7.1 and it works.