iOS无法移动UIView

Question

NSLog(@"Before: %f",_inputView.frame.origin.y);
[UIView animateWithDuration:animationDuration animations:^{
    [_inputView setFrame: CGRectMake(_inputView.frame.origin.x, 0, _inputView.frame.size.width, _inputView.frame.size.height)];
}completion:^(BOOL finished){
    NSLog(@"After: %f",_inputView.frame.origin.y);
}];

我使用此代码移动我的UIView，但它不移动。 （日志 - ＆gt;之前：520.00之后：520.00）