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。
一个更为优雅的解决方案是使用UIView子类(虽然这并不总是合适的),并在父帧更改时重新计算所有子视图(并且要聪明:只有在新帧大小发生更改时才重新计算它们,即在重写setFrame和调用[super setFrame:frame_]之前使用CGRectEqualToRect来比较新帧)。唯一的缺点是,您打算使用的UIViewController可能应该监听键盘事件(或者,您可以在UIView本身中进行监听,以方便封装)。但只有UIKeyboardWillShowNotification和UIKeyboard WillHideNotification。这只是为了让它看起来平滑(如果你等待CG调用它,你会得到一个波涛汹涌的时刻)。
无论如何,这有一个优点,那就是构建一个做正确事情的UIView子类。
天真的实现是重写drawRect:(不要),更好的方法是只使用layoutSubviews(然后在UIViewController中,或者在为显示或隐藏调用的SINGLE方法中调用[view setNeedsLayout])。
此解决方案摆脱了硬编码键盘偏移(如果它们不在拆分等中,则会发生变化),还意味着您的视图可以是许多其他视图的子视图,并且仍然可以正确响应。
除非没有其他解决方案,否则不要硬编码这样的东西。如果你做得对,操作系统会给你足够的信息,你只需要智能地重新绘制(基于你的新帧大小)。这要干净得多,而且是你应该做的事情。(不过,可能还有更好的方法。)
干杯
有很多答案可以告诉我们这个方法。我采取了相同的方法,但实施效果不佳。
这是基本想法。我修改了keyboardWasShown方法。
{
// Obtain keyboard Info
NSDictionary* info = [notification userInfo];
CGRect keyboardRect = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue];
keyboardRect = [self.view convertRect:keyboardRect fromView:nil];
// Obtain ScrollView Info w.r.t. top View
CGRect scrollViewRect = [self.view convertRect:self.scrollView.frame fromView:nil];
// Depending upon your screen Ui, Scroll View's bottom edge might be at some offset from screen's bottom
// Calculate the exact offset
int scrollViewBottomOffset = self.view.frame.size.height - (scrollViewRect.origin.y + scrollViewRect.size.height);
int heightToBeAdjusted = keyboardRect.size.height - scrollViewBottomOffset;
// We may also need to consider the Insets if already present with ScrollView. Let's keep it simple for now
// But we should store these, so that we can restore the Insets when Keyboard is gone
// origInsets = self.scrollView.contentInset;
// Set the new Insets for ScrollView
UIEdgeInsets contentInsets = UIEdgeInsetsMake(0.0, 0.0, heightToBeAdjusted, 0.0);
self.scrollView.contentInset = contentInsets;
self.scrollView.scrollIndicatorInsets = contentInsets;
// Visible frame (not overlapped by Keyboard)
CGRect visibleFrame = self.view.frame;
visibleFrame.size.height -= keyboardRect.size.height;
// Get the Rect for Textfield w.r.t self.view
CGRect activeFieldFrame = self.activeField.frame;
activeFieldFrame = [self.view convertRect:activeFieldFrame fromView:self.scrollView];
// Check if the TextField is Visible or not
if (!CGRectContainsRect(visibleFrame, activeFieldFrame) ) {
// Scroll to make it visible but for scrolling use the activeField frame w.r.t. to scroll View
[self.scrollView scrollRectToVisible:self.activeField.frame animated:YES];
}
}
并添加此方法来初始化activeField
- (IBAction)textFieldDidBeginEditing:(UITextField *)sender
{
self.activeField = sender;
}
如果文本字段未完全或部分隐藏,则我们不应更改任何内容。我们应该计算隐藏的精确相交区域(键盘的框架和文本字段的框架),然后我们应该更改视图的框架。这里我给出了一个完整的例子。声明3个变量
#定义衬垫10@接口PKViewController()@属性(非原子,赋值)CGRect-originalViewFrame//原始视图的框架@属性(非原子,强)UITextField*activeTextField;//当前文本字段@属性(非原子,赋值)CGRect keyBoardRect;//安全板覆盖面积@完
存储原始帧
- (void)viewDidLoad {
[super viewDidLoad];
_originalViewFrame = self.view.frame;
}
将视图控制器添加为键盘通知的观察者
- (void)viewWillAppear:(BOOL)animated{
[super viewWillAppear:animated];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardWasShown:)
name:UIKeyboardDidShowNotification
object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardWillHide:)
name:UIKeyboardWillHideNotification
object:nil];
}
移除观察者
- (void)viewWillDisappear:(BOOL)animated{
[super viewWillDisappear:animated];
[[NSNotificationCenter defaultCenter] removeObserver:self];
}
当键盘出现时存储键盘覆盖的区域,当键盘消失时将其设置为CGRectZero
- (void)keyboardWasShown:(NSNotification *)notification{
CGSize keyboardSize = [[[notification userInfo] objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;
_keyBoardRect = CGRectMake(0, _originalViewFrame.size.height - keyboardSize.height, keyboardSize.width, keyboardSize.height);
[self moveTextFieldUP];
}
- (void) keyboardWillHide:(NSNotification *)notification{
_keyBoardRect = CGRectZero;
[self setDefaultFrame];
}
存储活动文本字段
- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField {
_activeTextField = textField;
//When keyboard is already present but the textfield is hidden. Case:When return key of keyboard makes the next textfield as first responder
if (!CGRectIsEmpty(_keyBoardRect)) {
[self moveTextFieldUP];
}
return YES;
}
- (BOOL)textFieldShouldReturn:(UITextField *)textField{
[textField resignFirstResponder];
return YES;
}
现在我们应该改变视图的框架
- (void)moveTextFieldUP{
CGRect virtualTextFieldRect = CGRectMake(0, self.view.frame.origin.y, _activeTextField.frame.size.width, _activeTextField.frame.origin.y+_activeTextField.frame.size.height);
if (CGRectIntersectsRect(_keyBoardRect, virtualTextFieldRect)) {
CGRect intersectRect = CGRectIntersection(_keyBoardRect, virtualTextFieldRect);
CGFloat newY = _originalViewFrame.origin.y - intersectRect.size.height;
CGFloat newHeight = _originalViewFrame.size.height + intersectRect.size.height;
CGRect newFrame = CGRectMake(0, newY-PADDING, _originalViewFrame.size.width, newHeight+PADDING);
[UIView animateWithDuration:0.3 animations:^{
[self.view setFrame:newFrame];
}];
NSLog(@"Intersect");
}
}
- (void)setDefaultFrame {
[UIView animateWithDuration:0.3 animations:^{
[self.view setFrame:_originalViewFrame];
}];
}