What is a convenient way to check UITextFields for errors before allowing a form to submit? - objective-c

Question

I've been at this all day and just can't get my head around it. On a form in my app, I'm using -[UITextFieldDelegate textFieldDidEndEditing]: to register any errors and store them in an NSMutableArray instance variable formErrors.
I intend to use the formErrors when my submit button is pressed, or perhaps to disable the button disabled while there are errors on the form. The problem is the error count goes all over the place. I've just ended up confusing myself as you can see my code where I'm incrementing and decrementing in order to try and control what's going on but just confusing myself more.
Error messages get put on formErrors like this:
-(void)textFieldDidEndEditing:(UITextField *)textField {
if ( textField == [self nameField] ) {
if ( ([[textField text] isEqualToString:#""]) ) {
[formErrors addObject:#"What is your name?"];
errorCount++;
} else {
errorCount--;
if ( ([[textField text] length] < 2) || ([[textField text] length] > 20) ) {
[formErrors addObject:#"Name must contain a minimum of 2 and a maximum of 20 characters only."];
errorCount++;
} else {
errorCount--;
if ([[textField text] rangeOfCharacterFromSet:alphaSet].location != NSNotFound) {
[formErrors addObject:#"Name must contain letters and spaces only."];
errorCount++;
}
}
}
}
if (textField == [self ageField]) {
if ( ([[textField text] isEqualToString:#""]) ) {
[formErrors addObject:#"How old are you?"];
errorCount++;
} else {
errorCount--;
if ( ([[textField text] intValue]) < 1 || ([[textField text] intValue] > 120) ) {
[formErrors addObject:#"Please enter an age using a number between 1 and 120."];
errorCount++;
} else {
errorCount--;
if ([[textField text] rangeOfCharacterFromSet:numericSet].location != NSNotFound) {
[formErrors addObject:#"Age must be given in numbers."];
errorCount++;
}
}
}
}
My instance var:
{
NSMutableArray *formErrors;
}
Then initialise it in viewDidLoad:
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
formErrors = [[NSMutableArray alloc] init];
Then in prepareForSegue: I have some temporary code to check things are working:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
int errCount = [formErrors count];
// check if all textfield values are filled in if not then disallow form submit
for (NSString *error in formErrors) {
NSLog(#"Total %d errors, \n Error Message: %#", errCount, error);
}
All I want to do is, as I enter and leave fields, check if there are any errors; if there are, just store the error message in formErrors, so I can do what I need to do in the prepareForSegue:. Is this even the right approach? I've tried doing this many different ways but just keep on going in circles.
The submit button is linked to my segue and also is an outlet so I can enabled and disable it as I please.
Help would be appreciated
Kind regards

Answer 1

Your approach is a bit redundant. Validate your fields upon submission, cancel submission if there are any errors:
- (BOOL)shouldPerformSegueWithIdentifier:(NSString *)identifier sender:(id)sender {
NSMutableArray *errors = [NSMutableArray array];
if (self.nameTextField.text.length > 21) {
[errors addObject:#"Name cannot be longer than 21 symbols"];
}
else if (!self.nameTextField.text.length) {
[errors addObject:#"Please enter your name"];
}
if (!self.passwordTextField.text.length) {
[errors addObject:#"Please enter password"];
}
else if (!self.confirmPasswordTextField.text.length) {
[errors addObject:#"Please confirm your password"];
}
else if (self.passwordTextField.text.length < 6) {
[errors addObject:#"Password is too short, use at least 6 characters."];
}
else if (![self.passwordTextField.text isEqualToString:self.confirmPasswordTextField.text]) {
[errors addObject:#"Passwords do not match"];
}
if (!self.emailTextField.text.length) {
[errors addObject:#"Please enter your e-mail"];
}
if (!self.image) {
[errors addObject:#"Please choose a photo"];
}
if (errors.count) {
[[[UIAlertView alloc] initWithTitle:#"Error"
message:[errors componentsJoinedByString:#"\n"]
delegate:nil
cancelButtonTitle:#"OK"
otherButtonTitles:nil, nil] show];
return NO;
}
return YES;
}

Answer 2

You're on the right path, but here are a couple of observations.
First I would get rid of all the errorCount++ and errorCount-- lines. They don't make sense, because you can always count the items in your error array.
Every time you check your input fields, clear your error array, otherwise you will be having errors that might have been already corrected.
Inside your -(void)textFieldDidEndEditing:(UITextField *)textField method, don't only check the textfield that has been edited, because you wold need to keep track of the errors that were before, the ones that were corrected, and the new ones... too much trouble.
I think it's best to create a new method that checks all the information and returns an array of errors. Call this routine from textFieldDidEndEditing.
- (NSArray *)checkInputs
{
NSMutableArray *errors = [NSMutableArray array];
// Loop through the textfields and fill your array
return (NSArray *)errors;
}