Question

It might look simple but I cannot find a solution for this. In my application, I have many UITextFields. For example, let’s say I have a UITextField called textField. When I enter a string into textField, I should validate whether string is alphanumeric. How can I do this?

I also have a button, apart from textField. After entering into textField, when I press button, I should validate whether the entered string is alphanumeric by showing it with NSLog. So can anyone help me solving this with some example or sample code?

Answer 1

You can try following-

NSString *string = myTextField.text;
NSCharacterSet *alphanumericSet = [NSCharacterSet alphanumericCharacterSet];
NSCharacterSet *numberSet = [NSCharacterSet decimalDigitCharacterSet];
BOOL isAplhaNumericOnly= [[string stringByTrimmingCharactersInSet:alphanumericSet] isEqualToString:@""] && ![[string stringByTrimmingCharactersInSet:numberSet] isEqualToString:@""];

This bool will return true only if your string is alphanumeric and not numeric only.

EDITED:-

To Log bool-

NSLog(@"isAplhaNumericOnly: %d",isAplhaNumericOnly);

And to return from this function –

if(isAplhaNumericOnly) {
    return;
}

Also if you want to show some alert then you can write code for presenting the alert above return statement.