UITextField 限制输入字数

#pragma mark - UITextFieldDelegate

//限制输入字数
-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
if (textField==_nameT) {
NSInteger existedLength = textField.text.length;
NSInteger selectedLength = range.length;
NSInteger replaceLength = string.length;
if (existedLength - selectedLength + replaceLength > 11) {
return NO;
}
}
if (textField==_chickT) {
NSInteger existedLength = textField.text.length;
NSInteger selectedLength = range.length;
NSInteger replaceLength = string.length;
if (existedLength - selectedLength + replaceLength > 6) {
return NO;
}
}

return YES;
}