为什么在显示键盘时视图向下移动？
问题描述：
我有一个基于标签控制器的应用程序，我有一个uitextview选择哪个移动视图，当键盘出现，整个事情效果很好，直到我切换标签，当我回到这个标签，并尝试编辑uitextview视图向下移动，然后回到键盘出现的正常位置而不是向上移动。这里是整个代码为什么在显示键盘时视图向下移动？
- (void)textViewDidBeginEditing:(UITextView *)textField
{
[self keyboardWillShow];
}
-(void)textViewDidEndEditing:(UITextView *)textField
{
[self keyboardWillHide];
}
-(void)keyboardWillShow {
// Animate the current view out of the way
if (self.view.frame.origin.y >= 0)
{
[self setViewMovedUp:YES];
}
else if (self.view.frame.origin.y < 0)
{
[self setViewMovedUp:NO];
}
}
-(void)keyboardWillHide {
if (self.view.frame.origin.y >= 0)
{
[self setViewMovedUp:YES];
}
else if (self.view.frame.origin.y < 0)
{
[self setViewMovedUp:NO];
}
}
//method to move the view up/down whenever the keyboard is shown/dismissed
-(void)setViewMovedUp:(BOOL)movedUp
{
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:0.5]; // if you want to slide up the view
CGRect rect = self.view.frame;
if (movedUp)
{
// 1. move the view's origin up so that the text field that will be hidden come above the keyboard
// 2. increase the size of the view so that the area behind the keyboard is covered up.
rect.origin.y -= kOFFSET_FOR_KEYBOARD;
rect.size.height += kOFFSET_FOR_KEYBOARD;
}
else
{
// revert back to the normal state.
rect.origin.y += kOFFSET_FOR_KEYBOARD;
rect.size.height -= kOFFSET_FOR_KEYBOARD;
}
self.view.frame = rect;
[UIView commitAnimations];
}