UITextField - 不设置新帧（在动画中）

Question

我想要，那个searchField变形为targetFrame。

#1 这不是结果：

- (BOOL)searchBarShouldBeginEditing:(UISearchBar *)bar
{
    UITextField *searchField = [bar valueForKey:@"_searchField"];
    CGRect targetFrame =  CGRectMake(-50, 0, 200, 30);
    searchField.frame = targetFrame; //not result

    return YES;
}

#2 不正确，但转换：

- (BOOL)searchBarShouldBeginEditing:(UISearchBar *)bar
{
    UITextField *searchField = [bar valueForKey:@"_searchField"];
    searchField.frame = CGRectMake (10, 0, 200, 50); //must differ from CGRectZero

    [UIView animateWithDuration: 3.0
                     animations: ^{

                     CGRect targetFrame =  CGRectMake(-50, 0, 200, 30);
                     searchField.frame = targetFrame; 

    }];

    return YES;
}

然后使用#2，searchField 开始动画，但是默认大小（不是targetFrame）。

我想要，那个 searchField 转换为targetFrame。

PS

searchField.autoresizingMask = UIViewAutoresizingNone; 没有结果

Answer 1

试试下面的块：

   [UIView animateWithDuration:3.0
                          delay:0
                        options:UIViewAnimationOptionLayoutSubviews
                     animations:^{
                         CGRect targetFrame =  CGRectMake(-50, 0, 200, 30);
                         searchField.frame = targetFrame; 
                     }
                     completion:^(BOOL finished) {

   }];