//点击键盘的回车键
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    if ([string isEqualToString:@"\n"]) {
        //在这里写你当你点击回车键时执行的事件
        return NO;
    }
    return YES;
}