popviewcontroller重置scrollview contentoffset

Question

我有一个内置UITextfield的scrollview。当键盘出现时，我使用setContentOffset：animated：滚动滚动视图。但是，当按下“返回”按钮到popViewControllerAnimated：时，滚动视图会向下滚动。我希望弹出视图时滚动位置保持不变。知道如何让它正常工作吗？

谢谢！

// Called when the UIKeyboardDidShowNotification is sent.
- (void)keyboardWasShown:(NSNotification*)aNotification
{

...

// If active text field is hidden by keyboard, scroll it so it's visible
CGRect aRect = CGRectMake(0, 0, 320, 460-44-215);
aRect.size.height -= kbSize.height;
if (!CGRectContainsPoint(aRect, activeField.frame.origin) ) {
    CGPoint scrollPoint = CGPointMake(0.0, activeField.frame.origin.y-80);
    [sv setContentOffset:scrollPoint animated:YES];
}
}