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：
#pragma -mark UITextField Delegate
-(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;
[UIViewbeginAnimations:@"ResizeForKeyboard"context:nil];
[UIViewsetAnimationDuration: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);
[UIViewcommitAnimations];
}
//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);
}
//触摸view隐藏键盘——touchDown
- (IBAction)View_TouchDown:(id)sender {
// 发送resignFirstResponder.
[[UIApplication sharedApplication] sendAction:@selector(resignFirstResponder) to:nil from:nil forEvent:nil];
}