How to do validation on textfield? - iphone

Question

I am making a registration form, in which I have 8 text fields and one submit button.
Whenever the user fails to enter one of the text fields, upon click of submit button an error message should be generated.
And when the user fills all the text fields, on click of submit button it should go to the next page.
Please give me some advice, thanks.

Answer 1

Simple logic, in your Submit action check that your textField.text is not nil or empty (#""). If not textField.text show UIAlert. Like this
-(IBAction) submitButton
{
if(self.txtName == nil || [self.txtName.text isEqualToString:#""])
{
[self showErrorAlert];
}
if(self.txtEmail == nil || [self.txtEmail.text isEqualToString:#""])
{
[self showErrorAlert];
}
}
// and show error alert as
-(void) showErrorAlert
{
UIAlertView *ErrorAlert = [[UIAlertView alloc] initWithTitle:#""
message:#"All Fields are mandatory." delegate:nil
cancelButtonTitle:#"OK"
otherButtonTitles:nil, nil];
[ErrorAlert show];
[ErrorAlert release];
}

Answer 2

-(void)emptyTextfieldVaildation
{
if( ([TxtFieldName.text isEqualToString:#""]) || ([TxtFieldPaswrd.text isEqualToString:#""]) )
{
UIAlertView *ErrorAlert = [[UIAlertView alloc] initWithTitle:#"Error!!"
message:#"Please fill in the details." delegate:nil
cancelButtonTitle:#"OK"
otherButtonTitles:nil, nil];
[ErrorAlert show];
[ErrorAlert release];
}
else
{
// Action to be called on Submit button touch
}
}

Answer 3

Set the method on click of submit button
-(IBAction)submit:(id)sender
{
//Do all the textField Validation
}
Check the all textfield data by using
[textfield.text isEqualToString:#""]
put this into if statement for all text field.. If condition is true , then show alert View

Answer 4

You have to check all fields before, and there are several way to do this. You can control the lenght of text of each field and show an alert if some field is empty. You can check the length property of the NSString, so you can also operate on the length(e.g the password must be 8 char, otherwise Alert.).
If you have tagged these 8 textFields(or if you know that there are just this textfields in your view) a good way may be like this:
for(UITextField * tf in [self.view subviews]){
if(![tf.text length]>0){
//show the alert
}
}
hope this helps.

Answer 5

Last night I struggled with this too and I used
if ([myTextField.text length] == 0) {
// error code to handle empty text field.
}
to handle empty text field. It works, for empty text field, of course, but failed if there are some spaces in there. Some people in SO give suggestion to trim the string first before evaluate using the code above. See link
How to enable a UIButton if a textfield is not empty?

Answer 6

set tag property of all your text fields uniquely and access them using if(textFieldName.tag==*yourtag*) in button action event...