经过大量的试验和错误,我放弃了,并提出了这个问题。我见过很多人有类似的问题,但不能得到所有的答案工作正确。
我有一个由自定义单元格组成的UITableView。单元格由相邻的5个文本字段组成(有点像网格)。
当我试图滚动和编辑UITableView底部的单元格时,我不能设法让我的单元格正确地定位在键盘上方。
我看到过很多关于改变视图大小的回答……但到目前为止,没有一种效果很好。
谁能用一个具体的代码示例来阐明这样做的“正确”方式?
经过大量的试验和错误,我放弃了,并提出了这个问题。我见过很多人有类似的问题,但不能得到所有的答案工作正确。
我有一个由自定义单元格组成的UITableView。单元格由相邻的5个文本字段组成(有点像网格)。
当我试图滚动和编辑UITableView底部的单元格时,我不能设法让我的单元格正确地定位在键盘上方。
我看到过很多关于改变视图大小的回答……但到目前为止,没有一种效果很好。
谁能用一个具体的代码示例来阐明这样做的“正确”方式?
当前回答
我刚刚发现另一个bug时使用UITableViewController。当键盘出现时,它不会自动滚动。我注意到这是因为contentInsetAdjustmentBehavior = .never在UITableView上。
其他回答
在Swift中的一个例子,使用从UITableViewCell中获取UITextField的indexPath的文本字段的确切点:
func textFieldDidBeginEditing(textField: UITextField) {
let pointInTable = textField.convertPoint(textField.bounds.origin, toView: self.accountsTableView)
let textFieldIndexPath = self.accountsTableView.indexPathForRowAtPoint(pointInTable)
accountsTableView.scrollToRowAtIndexPath(textFieldIndexPath!, atScrollPosition: .Top, animated: true)
}
执行滚动的函数可以简单得多:
- (void) textFieldDidBeginEditing:(UITextField *)textField {
UITableViewCell *cell;
if (floor(NSFoundationVersionNumber) <= NSFoundationVersionNumber_iOS_6_1) {
// Load resources for iOS 6.1 or earlier
cell = (UITableViewCell *) textField.superview.superview;
} else {
// Load resources for iOS 7 or later
cell = (UITableViewCell *) textField.superview.superview.superview;
// TextField -> UITableVieCellContentView -> (in iOS 7!)ScrollView -> Cell!
}
[tView scrollToRowAtIndexPath:[tView indexPathForCell:cell] atScrollPosition:UITableViewScrollPositionTop animated:YES];
}
就是这样。根本不需要计算。
结合并填写几个答案(特别是Ortwin Gentz,用户98013)和另一篇文章中的空白,这将适用于iPad上的SDK 4.3的纵向或横向模式:
@implementation UIView (FindFirstResponder)
- (UIResponder *)findFirstResponder
{
if (self.isFirstResponder) {
return self;
}
for (UIView *subView in self.subviews) {
UIResponder *firstResponder = [subView findFirstResponder];
if (firstResponder != nil) {
return firstResponder;
}
}
return nil;
}
@end
@implementation MyViewController
- (UIResponder *)currentFirstResponder {
return [self.view findFirstResponder];
}
- (IBAction)editingEnded:sender {
[sender resignFirstResponder];
}
- (BOOL)textFieldShouldReturn:(UITextField *)textField {
[textField resignFirstResponder];
return NO;
}
- (void)textFieldDidBeginEditing:(UITextField *)textField {
UITableViewCell *cell = (UITableViewCell*) [[textField superview] superview];
[_tableView scrollToRowAtIndexPath:[_tableView indexPathForCell:cell] atScrollPosition:UITableViewScrollPositionTop animated:YES];
}
- (void)keyboardWillShow:(NSNotification*)notification {
if ([self currentFirstResponder] != nil) {
NSDictionary* userInfo = [notification userInfo];
// we don't use SDK constants here to be universally compatible with all SDKs ≥ 3.0
NSValue* keyboardFrameValue = [userInfo objectForKey:@"UIKeyboardBoundsUserInfoKey"];
if (!keyboardFrameValue) {
keyboardFrameValue = [userInfo objectForKey:@"UIKeyboardFrameEndUserInfoKey"];
}
// Reduce the tableView height by the part of the keyboard that actually covers the tableView
CGRect windowRect = [[UIApplication sharedApplication] keyWindow].bounds;
CGRect viewRectAbsolute = [_tableView convertRect:_tableView.bounds toView:[[UIApplication sharedApplication] keyWindow]];
CGRect frame = _tableView.frame;
if (UIInterfaceOrientationLandscapeLeft == self.interfaceOrientation ||UIInterfaceOrientationLandscapeRight == self.interfaceOrientation ) {
windowRect = CGRectMake(windowRect.origin.y, windowRect.origin.x, windowRect.size.height, windowRect.size.width);
viewRectAbsolute = CGRectMake(viewRectAbsolute.origin.y, viewRectAbsolute.origin.x, viewRectAbsolute.size.height, viewRectAbsolute.size.width);
}
frame.size.height -= [keyboardFrameValue CGRectValue].size.height - CGRectGetMaxY(windowRect) + CGRectGetMaxY(viewRectAbsolute);
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:[[userInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue]];
[UIView setAnimationCurve:[[userInfo objectForKey:UIKeyboardAnimationCurveUserInfoKey] intValue]];
_tableView.frame = frame;
[UIView commitAnimations];
UITableViewCell *textFieldCell = (id)((UITextField *)self.currentFirstResponder).superview.superview;
NSIndexPath *textFieldIndexPath = [_tableView indexPathForCell:textFieldCell];
// iOS 3 sends hide and show notifications right after each other
// when switching between textFields, so cancel -scrollToOldPosition requests
[NSObject cancelPreviousPerformRequestsWithTarget:self];
_topmostRowBeforeKeyboardWasShown = [[_tableView indexPathsForVisibleRows] objectAtIndex:0];
[_tableView scrollToRowAtIndexPath:textFieldIndexPath atScrollPosition:UITableViewScrollPositionMiddle animated:YES];
}
}
- (void) scrollToOldPosition {
[_tableView scrollToRowAtIndexPath:_topmostRowBeforeKeyboardWasShown atScrollPosition:UITableViewScrollPositionTop animated:YES];
}
- (void)keyboardWillHide:(NSNotification*)notification {
if ([self currentFirstResponder] != nil) {
NSDictionary* userInfo = [notification userInfo];
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:[[userInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue]];
[UIView setAnimationCurve:[[userInfo objectForKey:UIKeyboardAnimationCurveUserInfoKey] intValue]];
_tableView.frame = self.view.bounds;
[UIView commitAnimations];
[self performSelector:@selector(scrollToOldPosition) withObject:nil afterDelay:0.1];
}
}
@end
如果你的UITableView是由UITableViewController的子类管理的,而不是UITableView,并且文本字段委托是UITableViewController,它应该自动管理所有的滚动——所有这些其他注释在实践中是很难实现的。
有关一个好例子,请参阅apple示例代码项目:TaggedLocations。
你可以看到它自动滚动,但似乎没有任何代码做到这一点。该项目还具有自定义表视图单元格,因此,如果使用它作为指南构建应用程序,应该会得到预期的结果。
Swift 3-4动画和键盘帧改变的解决方案:
首先,创建Bool类型:
// MARK: - Private Properties
private var isKeyboardShowing = false
其次,在系统键盘通知中添加观察者:
// MARK: - Overriding ViewController Life Cycle Methods
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name: .UIKeyboardWillShow, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide), name: .UIKeyboardWillHide, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillChangeFrame), name: .UIKeyboardWillChangeFrame, object: nil)
}
第三,准备动画功能:
func adjustTableViewInsets(keyboardHeight: CGFloat, duration: NSNumber, curve: NSNumber){
var extraHeight: CGFloat = 0
if keyboardHeight > 0 {
extraHeight = 20
isKeyboardShowing = true
} else {
isKeyboardShowing = false
}
let contentInset = UIEdgeInsets(top: 0, left: 0, bottom: keyboardHeight + extraHeight, right: 0)
func animateFunc() {
//refresh constraints
//self.view.layoutSubviews()
tableView.contentInset = contentInset
}
UIView.animate(withDuration: TimeInterval(duration), delay: 0, options: [UIViewAnimationOptions(rawValue: UInt(curve))], animations: animateFunc, completion: nil)
}
然后添加target/action方法(由观察者调用):
// MARK: - Target/Selector Actions
func keyboardWillShow(notification: NSNotification) {
if !isKeyboardShowing {
if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
let keyboardHeight = keyboardSize.height
let duration = notification.userInfo?[UIKeyboardAnimationDurationUserInfoKey] as! NSNumber
let curve = notification.userInfo?[UIKeyboardAnimationCurveUserInfoKey] as! NSNumber
adjustTableViewInsets(keyboardHeight: keyboardHeight, duration: duration, curve: curve)
}
}
}
func keyboardWillHide(notification: NSNotification) {
let duration = notification.userInfo?[UIKeyboardAnimationDurationUserInfoKey] as! NSNumber
let curve = notification.userInfo?[UIKeyboardAnimationCurveUserInfoKey] as! NSNumber
adjustTableViewInsets(keyboardHeight: 0, duration: duration, curve: curve)
}
func keyboardWillChangeFrame(notification: NSNotification) {
if isKeyboardShowing {
let duration = notification.userInfo?[UIKeyboardAnimationDurationUserInfoKey] as! NSNumber
let curve = notification.userInfo?[UIKeyboardAnimationCurveUserInfoKey] as! NSNumber
if let newKeyboardSize = (notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
let keyboardHeight = newKeyboardSize.height
adjustTableViewInsets(keyboardHeight: keyboardHeight, duration: duration, curve: curve)
}
}
}
最后,不要忘记在deinit或viewWillDisappear中删除观察者:
deinit {
NotificationCenter.default.removeObserver(self)
}