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];
}