textField 和 按钮

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range
replacementString:(NSString *)string
{
if ((range.location ==
0) && [string isEqualToString:@""]) {//
还有个小bug，当选取第一个字符后面所有的内容删除后，按钮会灰。
_btnQueDing.enabled =
NO;
_btnQueDing.backgroundColor =
BackColorGrayGlk1;

}else
{
_btnQueDing.enabled =
YES;
_btnQueDing.backgroundColor =
oragineColorGlk1;
}
return
YES;
}