Creating NSError * results in application crash - objective-c

Question

I have the following situation:
My domain class gets some input validates it, and if validation passes it proceeds with saving data.
When control flow reaches the if statements, the application crashes
- (BOOL)createGmailAccountWithName:(NSString *)name
email:(NSString *)email
andPassword:(NSString *)password
error: (NSError **) error {
if (!name || name.length == 0) {
*error = [self createError:#"name"];
return NO;
}
if (!email || email.length == 0) {
*error = [self createError:#"email"];
return NO;
}
if (!password || password.length == 0) {
*error = [self createError:#"password"];
return NO;
}
//..
}
-(NSError *) createError: (NSString *) field {
NSString *errorMessage = [NSString stringWithFormat:#"Property %# is required", field];
NSDictionary *userInfo = #{
NSLocalizedFailureReasonErrorKey: NSLocalizedString(errorMessage, nil)
};
NSError *error = [NSError errorWithDomain:ACCOUNT_STORE_ERROR_DOMAIN
code:-1
userInfo:userInfo];
return error;
}
When I comment out all lines where the validation happens, the application does not crash.
I have no idea why this is happening. Can anyone point me into the right direction?

Answer 1

If you have this method:
- (BOOL)createGmailAccountWithName:(NSString *)name
email:(NSString *)email
andPassword:(NSString *)password
error: (NSError **) error
Folks are probably going to call it either like this:
NSError *error;
[accountCreator createGmailAccountWithName:#"Ben"
email:#"foo#example.com"
andPassword:#"pwd"
error:&error];
if (error)
{
NSLog(#"Hey I got an error: %#", error);
}
Or like this:
[accountCreator createGmailAccountWithName:#"Ben"
email:#"foo#example.com"
andPassword:#"pwd"
error:NULL];
// I couldn't care less about an error
In the second case, your code will will try to dereference **error, *error is not a valid pointer and would cause a crash.