ios 含有textfield的viewcontroller随键盘弹起而改变位置

具体实现代码：
-(void)textFieldDidBeginEditing:(UITextField *)textField{
NSTimeInterval animationDuration = 0.30f;
[UIView beginAnimations:@"ResizeForKeyboard" context:nil];
[UIView setAnimationDuration:animationDuration];
if ([UIScreen mainScreen].bounds.size.width>320) {
//将视图的Y坐标向上移动，以使下面腾出地方用于软键盘的显示
self.view.frame = CGRectMake(0.0f, -200.0f, self.view.frame.size.width, self.view.frame.size.height);//64-216
[UIView commitAnimations];
}
else{
self.view.frame = CGRectMake(0.0f, -170.0f, self.view.frame.size.width, self.view.frame.size.height);
[UIView commitAnimations];
}
}

-(void)textFieldDidEndEditing:(UITextField *)textField{
//滑动效果
NSTimeInterval animationDuration = 0.30f;
[UIView beginAnimations:@"ResizeForKeyboard" context:nil];
[UIView setAnimationDuration:animationDuration];

//恢复屏幕
self.view.frame = CGRectMake(0.0f, 0.0f, self.view.frame.size.width, self.view.frame.size.height);//64-216

[UIView commitAnimations];
}