使用iOS SDK：
我有一个带UITextFields的UIView，可以启动键盘。我需要它能够：
启动键盘后，允许滚动UIScrollView的内容以查看其他文本字段自动“跳转”（通过向上滚动）或缩短
我知道我需要一个UIScrollView。我已经尝试将UIView的类更改为UIScrollView，但仍然无法上下滚动文本框。
我需要UIView和UIScrollView吗？一个在另一个里面吗？
要自动滚动到活动文本字段，需要执行哪些操作？
理想情况下，尽可能多的组件设置将在Interface Builder中完成。我只想编写需要的代码。
注意：我使用的UIView（或UIScrollView）是由一个选项卡（UITabBar）启动的，它需要正常工作。
我正在添加滚动条，只为键盘出现时使用。尽管不需要它，但我觉得它提供了一个更好的界面，例如，用户可以滚动和更改文本框。
当键盘上下移动时，我可以改变UIScrollView的框架大小。我只是在使用：
-(void)textFieldDidBeginEditing:(UITextField *)textField {
//Keyboard becomes visible
scrollView.frame = CGRectMake(scrollView.frame.origin.x,
scrollView.frame.origin.y,
scrollView.frame.size.width,
scrollView.frame.size.height - 215 + 50); // Resize
}
-(void)textFieldDidEndEditing:(UITextField *)textField {
// Keyboard will hide
scrollView.frame = CGRectMake(scrollView.frame.origin.x,
scrollView.frame.origin.y,
scrollView.frame.size.width,
scrollView.frame.size.height + 215 - 50); // Resize
}
然而，这不会自动“向上移动”或将可见区域中的下部文本字段居中，这是我真正想要的。
我对UIScrollView由多个UITextField组成也有很多问题，其中一个或多个在编辑时会被键盘遮挡。
如果UIScrollView滚动不正确，请考虑以下几点。
1） 确保contentSize大于UIScrollView框架大小。理解UIScrollViews的方法是UIScrollView就像一个查看contentSize中定义的内容的窗口。因此，如果要让UIScrollview滚动到任何位置，contentSize必须大于UIScrollview。否则，不需要滚动，因为contentSize中定义的所有内容都已可见。BTW，默认contentSize=CGSizeZero。
2） 既然您已经了解到UIScrollView实际上是一个“内容”窗口，那么确保键盘不会遮挡UIScroll View的查看“窗口”的方法就是调整UIScrollView的大小，这样当键盘出现时，UIScrollView窗口的大小就等于UIScrollviewframe.size.height减去键盘的高度。这将确保您的窗口仅是那个小的可视区域。
3） 这里有一个陷阱：当我第一次实现这一点时，我想我必须获得编辑文本字段的CGRect，并调用UIScrollView的scrollRecToVisible方法。我通过调用scrollRecToVisible方法实现了UITextFieldDelegate方法textFieldDidBeginEditing。这实际上产生了一个奇怪的副作用，即滚动会将UITextField捕捉到位。在很长一段时间里，我都搞不清那是什么。然后我注释了textFieldDidBegginEditingDelegate方法，这一切都奏效了！！(???). 事实证明，我相信UIScrollView实际上隐式地将当前编辑的UITextField带入可视窗口。我对UITextFieldDelegate方法的实现以及随后对scrollRecToVisible的调用是多余的，这是产生奇怪副作用的原因。
因此，当键盘出现时，以下是在UIScrollView中正确滚动UITextField的步骤。
// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad
{
[super viewDidLoad];
// register for keyboard notifications
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardWillShow:)
name:UIKeyboardWillShowNotification
object:self.view.window];
// register for keyboard notifications
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardWillHide:)
name:UIKeyboardWillHideNotification
object:self.view.window];
keyboardIsShown = NO;
//make contentSize bigger than your scrollSize (you will need to figure out for your own use case)
CGSize scrollContentSize = CGSizeMake(320, 345);
self.scrollView.contentSize = scrollContentSize;
}
- (void)keyboardWillHide:(NSNotification *)n
{
NSDictionary* userInfo = [n userInfo];
// get the size of the keyboard
CGSize keyboardSize = [[userInfo objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue].size;
// resize the scrollview
CGRect viewFrame = self.scrollView.frame;
// I'm also subtracting a constant kTabBarHeight because my UIScrollView was offset by the UITabBar so really only the portion of the keyboard that is leftover pass the UITabBar is obscuring my UIScrollView.
viewFrame.size.height += (keyboardSize.height - kTabBarHeight);
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationBeginsFromCurrentState:YES];
[self.scrollView setFrame:viewFrame];
[UIView commitAnimations];
keyboardIsShown = NO;
}
- (void)keyboardWillShow:(NSNotification *)n
{
// This is an ivar I'm using to ensure that we do not do the frame size adjustment on the `UIScrollView` if the keyboard is already shown. This can happen if the user, after fixing editing a `UITextField`, scrolls the resized `UIScrollView` to another `UITextField` and attempts to edit the next `UITextField`. If we were to resize the `UIScrollView` again, it would be disastrous. NOTE: The keyboard notification will fire even when the keyboard is already shown.
if (keyboardIsShown) {
return;
}
NSDictionary* userInfo = [n userInfo];
// get the size of the keyboard
CGSize keyboardSize = [[userInfo objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue].size;
// resize the noteView
CGRect viewFrame = self.scrollView.frame;
// I'm also subtracting a constant kTabBarHeight because my UIScrollView was offset by the UITabBar so really only the portion of the keyboard that is leftover pass the UITabBar is obscuring my UIScrollView.
viewFrame.size.height -= (keyboardSize.height - kTabBarHeight);
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationBeginsFromCurrentState:YES];
[self.scrollView setFrame:viewFrame];
[UIView commitAnimations];
keyboardIsShown = YES;
}
在viewDidLoad上注册键盘通知在viewDidUnload中注销键盘nofitions确保contentSize设置为大于UIScrollView at viewDidLoad当有键盘时，缩小UIScrollView当键盘离开时，恢复UIScrollView。使用ivar来检测键盘是否已经显示在屏幕上，因为每次UITextField选项卡时都会发送键盘通知，即使键盘已经存在，以避免在UIScrollView已经缩小时缩小它
需要注意的一点是，当您单击另一个UITextField时，即使键盘已经在屏幕上，UIKeyboardWillShowNotification也会启动。当键盘已经在屏幕上时，我使用ivar来避免调整UIScrollView的大小。当键盘已经存在时，不小心调整UIScrollView的大小将是灾难性的！
希望这段代码能让你们中的一些人省去很多麻烦。
注意：此答案假设您的textField位于scrollView中。
我更喜欢使用scrollContentInset和scrollContentOffset来处理这个问题，而不是干扰视图的框架。
首先让我们听听键盘通知
//call this from viewWillAppear
-(void)addKeyboardNotifications
{
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardWillShow:)
name:UIKeyboardWillShowNotification
object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardWillHide:)
name:UIKeyboardWillHideNotification
object:nil];
}
//call this from viewWillDisappear
-(void)removeKeyboardNotifications{
[[NSNotificationCenter default
Center] removeObserver:self name:UIKeyboardWillShowNotification object:nil];
[[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillHideNotification object:nil];
}
下一步是保留表示当前第一响应者的属性（当前具有键盘的UITextfield/UUITextVIew）。
我们使用委托方法来设置此属性。如果您正在使用另一个组件，则需要类似的组件。
请注意，对于textfield，我们在didBegginEditing中设置它，而对于textView，我们在shouldBeginEditing中将其设置。这是因为出于某种原因，在UIKeyboardWillShowNotification之后调用textViewDidBegginEditing。
-(BOOL)textViewShouldBeginEditing:(UITextView * )textView{
self.currentFirstResponder = textView;
return YES;
}
-(void)textFieldDidBeginEditing:(UITextField *)textField{
self.currentFirstResponder = textField;
}
最后，这里是魔术
- (void)keyboardWillShow:(NSNotification*)aNotification{
NSDictionary* info = [aNotification userInfo];
CGRect kbFrame = [[info objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
/*if currentFirstResponder is overlayed by the keyboard, move it so it bottom ends where the keyboard begins*/
if(self.currentFirstResponder){
//keyboard origin in currentFirstResponderFrame
CGPoint keyboardOrigin = [self.currentFirstResponder convertPoint:kbFrame.origin fromView:nil];
float spaceBetweenFirstResponderAndKeyboard = abs(self.currentFirstResponder.frame.size.height-keyboardOrigin.y);
//only scroll the scrollview if keyboard overlays the first responder
if(spaceBetweenFirstResponderAndKeyboard>0){
//if i call setContentOffset:animate:YES it behaves differently, not sure why
[UIView animateWithDuration:0.25 animations:^{
[self.scrollView setContentOffset:CGPointMake(0,self.scrollView.contentOffset.y+spaceBetweenFirstResponderAndKeyboard)];
}];
}
}
//set bottom inset to the keyboard height so you can still scroll the whole content
UIEdgeInsets contentInsets = UIEdgeInsetsMake(0.0, 0.0, kbFrame.size.height, 0.0);
_scrollView.contentInset = contentInsets;
_scrollView.scrollIndicatorInsets = contentInsets;
}
- (void)keyboardWillHide:(NSNotification*)aNotification{
UIEdgeInsets contentInsets = UIEdgeInsetsZero;
_scrollView.contentInset = contentInsets;
_scrollView.scrollIndicatorInsets = contentInsets;
}
