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Answer 1

A:

Use NSScanner to detect whether a valid integer is in the string.

NSScanner * scanner = [NSScanner scannerWithString:myTextField.text];
NSInteger * integer;
if([scanner scanInteger:&integer]) {
  // valid number found
} else {
  // cry about it
}

You can improve on this by validating the text in the UITextField delegate method textField:shouldChangeCharactersInRange:replacementString: to prevent the user from even entering an invalid value.

codewarrior 2010-04-01 00:01:01

Using `scanDouble:` would have the same side-effect as `doubleValue` of allowing the 'f' character, since it indicates floating-point values in C. What you can do instead is use the delegate method to prevent the user from entering the 'f'.

codewarrior 2010-04-01 00:05:18

the Delegate Method does not seem to work, I have connected the controls Delegate

Jimmy 2010-04-01 00:09:23

"does not seem to work" is too vague, we'll need more details.

codewarrior 2010-04-01 01:59:33

`scanDouble:` is not "allowing" the 'f' character, it's just stopping the scan when it hits it. To verify that the field contains only the number, with no trailing garbage, you need to test `[scanner isAtEnd]` after `scanDouble:` returns successfully.

David Gelhar 2010-04-01 03:39:50

Also, think about using a numeric keyboard: `textField.keyboardType = UIKeyboardTypeNumberPad`

0xced 2010-04-01 09:37:56

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UITextfield check if its a number

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