获得键盘高度以及UITableView中多个UITextField时UITableView的滚动和键盘的隐藏

1.获得键盘高度

 (UIView *)keyboardViewNotepad;
{
        NSArray *windows = [self windows];
        for (UIWindow *window in [windows reverseObjectEnumerator])
        {
                for (UIView *view in [window subviews])
                {
                        if (!strcmp(object_getClassName(view), "UIPeripheralHostView") || !strcmp(object_getClassName(view), "UIKeyboard"))
                        {
                                return view;
                        }
                }
        }
        
        return nil;
}

得到UIView *keyboardView = [**** keyboardViewNotepad]；

UITableView中多个UITextField时，编辑textfield 时 UITableView 自动滚动到当前textfield 可见的行即不被键盘遮住，及键盘的显示和隐藏的问题

1、 采用 NSNotificationCenter 方式

在 .h 文件中 添加两个变量后面会用到

int keyboardHeight;
BOOL keyboardIsShowing;

@property (nonatomic, retain) UITextField *currentTextField;

在.m 文件里
@synthesize currentTextField = _currentTextField;

首先，在你的viewWillAppear：订阅到键盘上的通知，让你知道什么时候键盘会显示和隐藏，系统会告诉你的键盘大小，但是不要忘记注销您的viewWillDisappear：

- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];
}

- (void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated];
[[NSNotificationCenter defaultCenter] removeObserver:self];
}

实现方法类似下面这样你调整你曾经为tableView匹配的键盘显示可视面积的大小。不要忘了执行keyboardWillHide：

-(void) keyboardWillShow:(NSNotification *)note {

CGRect keyboardBounds;

[[note.userInfo valueForKey:UIKeyboardWillShowNotification] getValue: &keyboardBounds];

keyboardHeight = keyboardBounds.size.height;

if (keyboardIsShowing == NO) {

keyboardIsShowing = YES;
CGRect frame = self.view.frame;
frame.size.height -= keyboardHeight;
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationBeginsFromCurrentState:YES];
[UIView setAnimationDuration:0.3f];
self.view.frame = frame;
[UIView commitAnimations];
}
}

- (void)keyboardWillHide:(NSNotification*)notification {

if (!keyboardIsShowing) {
return;
}

NSDictionary* userInfo = [notification userInfo];
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:[[userInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue]];
[UIView setAnimationCurve:[[userInfo objectForKey:UIKeyboardAnimationCurveUserInfoKey] intValue]];

//CGRect rect = self.view.bounds;
//self.tableView.frame = CGRectMake(0, 0, 320, 416);
NSValue *value = [userInfo objectForKey:UIKeyboardFrameBeginUserInfoKey];
CGSize keyboardSize = [value CGRectValue].size;
CGRect viewFrame = self.view.frame;
viewFrame.size.height +=keyboardSize.height;
keyboardIsShowing = NO;
[UIView commitAnimations];
}

- (void)textFieldDidBeginEditing:(UITextField *)textField
{
self.currentTextField = textField;
NSIndexPath *indexPath = [self.tableView indexPathForCell:(UITableViewCell *) [self.tableView viewWithTag:self.currentTextField.tag]];

UITableViewCell *cell = (UITableViewCell *) [textField superview];
indexPath = [self.tableView indexPathForCell:cell];
//[self.tableView scrollToRowAtIndexPath:indexPath atScrollPosition:UITableViewScrollPositionTop animated:YES];
//int currentIndex = textField.tag;
CGRect frame = textField.frame;
CGFloat rowHeight = self.tableView.rowHeight;
//下面的代码只是为了判断是哪一个textField,可以根据自己的情况进行修改，我为了测试加了7个
if (indexPath.row == 0) {
frame.origin.y += rowHeight * 0;
} else if (indexPath.row==1) {
frame.origin.y += rowHeight * 1;
} else if (indexPath.row == 2) {
frame.origin.y += rowHeight * 2;
} else if (indexPath.row ==3){
frame.origin.y += rowHeight * 3;
}else if(indexPath.row==4)
{
frame.origin.y +=rowHeight *4;
} else if(indexPath.row==5)
{
frame.origin.y +=rowHeight *5;
} else if(indexPath.row==6)
{
frame.origin.y +=rowHeight *6;
}
CGFloat viewHeight = self.tableView.frame.size.height;
CGFloat halfHeight = viewHeight / 2;
CGFloat halfh= frame.origin.y +(textField.frame.size.height / 2);

if(halfh<halfHeight){
frame.origin.y = 0;
frame.size.height =halfh;
}else{
frame.origin.y =halfh;
frame.size.height =halfh;
}
[self.tableView scrollRectToVisible:frame animated:YES ];
}

点击done（完成）按钮关闭键盘，可以在UIControlEventEditingDidEndOnExit 响应事件

[textField addTarget:self action:@selector(textFieldDoneEditing:) forControlEvents:UIControlEventEditingDidEndOnExit];

-(IBAction)textFieldDoneEditing:(id)sender
{
self.currentTextField = (UITextField *)sender;
[self.currentTextField resignFirstResponder];
[sender resignFirstResponder];
//[self.tableView scrollRectToVisible:self.currentTextField.frame animated:YES];
}

2、采用 scrollToRowAtIndexPath

点击done（完成）按钮关闭键盘，可以在UIControlEventEditingDidEndOnExit 响应事件

[textField addTarget:self action:@selector(textFieldDoneEditing:)forControlEvents:UIControlEventEditingDidEndOnExit];

-(IBAction)textFieldDoneEditing:(id)sender
{
self.currentTextField = (UITextField *)sender;
[self.currentTextField resignFirstResponder];
[sender resignFirstResponder];
[self.tableView scrollRectToVisible:self.currentTextField.frame animated:YES];
}

- (void)textFieldDidBeginEditing:(UITextField *)textField

{
self.currentTextField = textField;
NSIndexPath *indexPath = [self.tableView indexPathForCell:(UITableViewCell *) [self.tableView viewWithTag:self.currentTextField.tag]];

//这里要看textField 是直接加到cell 上的还是加的 cell.contentView上的

//直接加到cell 上

UITableViewCell *cell = (UITableViewCell *) [textField superview];
indexPath = [self.tableView indexPathForCell:cell];

[self.tableView scrollToRowAtIndexPath:indexPath atScrollPosition:UITableViewScrollPositionTop animated:YES];

}