从横向切换到纵向后，将 UIScrollView 保持在正确的位置

Question

我有一个 UIScrollView，其中包含一个文本字段和一个文本视图。当键盘存在时，我有代码可以将文本字段向上移动，这样键盘就不会覆盖文本字段。此代码在纵向视图中效果很好：

-(BOOL)textFieldShouldReturn:(UITextField *)textField {
    if(textField) {
        [textField resignFirstResponder];
    }
    return NO;
}

-(void)textFieldDidBeginEditing:(UITextField *)textField {
    if (textField == self.nameField) {
        [UIView beginAnimations:nil context:NULL];
        [UIView setAnimationDelegate:self];
        [UIView setAnimationDuration:0.3];
        [UIView setAnimationBeginsFromCurrentState:YES];
        self.view.frame = CGRectMake(self.view.frame.origin.x,   (self.view.frame.origin.y - 90), self.view.frame.size.width, self.view.frame.size.height);
        [UIView commitAnimations];
    }
}

-(void)textFieldDidEndEditing:(UITextField *)textField {
    if (textField == self.nameField) {
        [UIView beginAnimations:nil context:NULL];
        [UIView setAnimationDelegate:self];
        [UIView setAnimationDuration:0.3];
        [UIView setAnimationBeginsFromCurrentState:YES];
        self.view.frame = CGRectMake(self.view.frame.origin.x, (self.view.frame.origin.y + 90), self.view.frame.size.width, self.view.frame.size.height);
        [UIView commitAnimations];
    }
}

-(void)textViewDidBeginEditing:(UITextView *)textField {
    if (textField == self.questionField) {
        [UIView beginAnimations:nil context:NULL];
        [UIView setAnimationDelegate:self];
        [UIView setAnimationDuration:0.3];
        [UIView setAnimationBeginsFromCurrentState:YES];
        self.view.frame = CGRectMake(self.view.frame.origin.x, (self.view.frame.origin.y - 200), self.view.frame.size.width, self.view.frame.size.height);
        [UIView commitAnimations];
    }
}

-(void)textViewShouldEndEditing:(UITextView *)textField {
    if (textField == self.questionField) {
        [UIView beginAnimations:nil context:NULL];
        [UIView setAnimationDelegate:self];
        [UIView setAnimationDuration:0.3];
        [UIView setAnimationBeginsFromCurrentState:YES];
        UIInterfaceOrientation interfaceOrientation = self.interfaceOrientation;

        self.view.frame = CGRectMake(self.view.frame.origin.x, (self.view.frame.origin.y + 200), self.view.frame.size.width, self.view.frame.size.height);
        [UIView commitAnimations];
    }
}

当我将 iPhone 模拟器旋转到横向视图时，这（不足为奇）不起作用。在横向和纵向视图中输入文本时，如何使文本字段向上移动足以看到它？

此外，如果我在显示键盘时从横向旋转到纵向，则在关闭键盘后，滚动视图会在屏幕上向下移动，而不是在其原始位置排列。我怎样才能避免这种情况？

Answer 1

Apple 的文档 Managing the Keyboard 在“移动位于键盘下方的内容”标题下显示了执行此操作的正确方法。

您基本上将您的内容放在滚动视图上并使用UIKeyboardDidShowNotification 和UIKeyboardWillHideNotification 通知来调整内容偏移量。

但是，代码有些不完整。键盘大小计算在横向模式下不起作用。要修复它，请替换它：

CGSize kbSize = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;

有了这个：

// Works in both portrait and landscape mode
CGRect kbRect = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue];
kbRect = [self.view convertRect:kbRect toView:nil];

CGSize kbSize = kbRect.size;