iOS UITextField限制輸入字數，iosuitextfield

iOS UITextField限制輸入字數，iosuitextfield

關於iOS的文字框有時需要限制字數，如手機號，在UITextField的代理單純寫一個判斷，在字數超過限制時，這時再想刪除就刪除不掉，可以在代理這樣寫，就解決

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{    if (!string.length)    {        return YES;    }       if (textField.keyboardType == UIKeyboardTypeNumberPad)    {        if ([string rangeOfCharacterFromSet:[[NSCharacterSet decimalDigitCharacterSet] invertedSet]].location != NSNotFound)        {            return NO;        }    }        NSString *updatedText = [textField.text stringByReplacingCharactersInRange:range withString:string];        if (updatedText.length > 11) // 4 was chosen for SSN verification    {        if (string.length > 1)        {            // BasicAlert(@"", @"This field accepts a maximum of 4 characters.");        }                return NO;    }        return YES;}