实现方法：

   1）将输入框的代理设置为self

       （在lb文件中将输入框的delegate设置为File’s Owner 。或者使用代码textField.delegate = self;

   2）将输入框所对应的ViewController.h设置实现了UITextFieldDelegate协议

         在ViewController.m文件中实现UITextFieldDelegate的三个方法即可：

      //开始编辑输入框的时候，软键盘出现，执行此事件        -(void)textFieldDidBeginEditing:(UITextField *)textField        {            CGRect frame = textField.frame;            int offset = frame.origin.y + 32 - (self.view.frame.size.height - 216.0);//键盘高度216                        NSTimeInterval animationDuration = 0.30f;            [UIView beginAnimations:@"ResizeForKeyboard" context:nil];            [UIView setAnimationDuration:animationDuration];                        //将视图的Y坐标向上移动offset个单位，以使下面腾出地方用于软键盘的显示            if(offset > 0)                self.view.frame = CGRectMake(0.0f, -offset, self.view.frame.size.width, self.view.frame.size.height);                        [UIView commitAnimations];        }                //当用户按下return键或者按回车键，keyboard消失        -(BOOL)textFieldShouldReturn:(UITextField *)textField        {            [textField resignFirstResponder];            return YES;        }                //输入框编辑完成以后，将视图恢复到原始状态        -(void)textFieldDidEndEditing:(UITextField *)textField        {            self.view.frame =CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);        }  

方法很简单吧？请注意一定不要忘记设置输入框的代理delegate哦