Add hidden UIView to UITableView similar to UIRefreshControl - ios

Question

Very similar to a UIRefreshControl, I'm trying to put a UIView on top of a UITableView. Dragging down the table view should reveal the view and have it stay there. Dragging up should hide it again and then scroll the table view. When hidden the table view should scroll normally. Scrolling back to the top should either reveal the hidden view again, or snap to the hidden state. Ultimately the revealed view should contain some buttons or a segmented control. It should look and behave very similar to the OmniFocus App.
Hidden View in OmniFocus
Revealed View in OmniFocus
This is how far I got. Especially the snapping back to the hidden state when the table view scrolls back up does not work. If you time it right you'll end up stuck in the middle of top view, which is exactly not what I want.
static CGFloat const kTopViewHeight = 40;
#interface ViewController ()
#property (nonatomic, weak) UIView *topView;
#property (nonatomic, assign) CGFloat dragStartY;
#end
#implementation ViewController
#pragma mark - View Lifecycle
- (void)viewDidLoad
{
CGRect topViewFrame = CGRectMake(0.0, -kTopViewHeight, 320, kTopViewHeight);
UIView *myView = [[UIView alloc] initWithFrame:topViewFrame];
myView.backgroundColor = [UIColor greenColor]; // DEBUG
self.topView = myView;
[self.tableView addSubview:myView];
}
#pragma mark - UIScrollViewDelegate
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{
NSLog(#"scrollViewWillBeginDragging %#", NSStringFromCGPoint(scrollView.contentOffset));
self.dragStartY = scrollView.contentOffset.y;
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
NSLog(#"scrollViewDidScroll %#", NSStringFromCGPoint(scrollView.contentOffset));
if (scrollView.contentOffset.y > 0) {
// reset the inset
scrollView.contentInset = UIEdgeInsetsZero;
} else if (scrollView.contentOffset.y >= -kTopViewHeight) {
// set the inset for the section headers
scrollView.contentInset = UIEdgeInsetsMake(-scrollView.contentOffset.y, 0, 0, 0);
} else if (scrollView.contentOffset.y < -kTopViewHeight) {
// don't scroll further when the topView's height is reached
scrollView.contentInset = UIEdgeInsetsMake(-kTopViewHeight, 0, 0, 0);
scrollView.contentOffset = CGPointMake(0, -kTopViewHeight);
}
}
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{
NSLog(#"scrollViewDidEndDragging %#", NSStringFromCGPoint(scrollView.contentOffset));
CGFloat yOffset = scrollView.contentOffset.y;
if (yOffset < 0) {
BOOL dragDown = self.dragStartY > yOffset;
CGFloat dragThreshold = 10;
if (dragDown) {
if (yOffset <= -dragThreshold) {
[self snapDown:YES scrollView:scrollView];
} else {
[self snapDown:NO scrollView:scrollView];
}
} else if (!dragDown) {
if (yOffset >= dragThreshold - kTopViewHeight) {
[self snapDown:NO scrollView:scrollView];
} else {
[self snapDown:YES scrollView:scrollView];
}
}
}
}
- (void)snapDown:(BOOL)down scrollView:(UIScrollView *)scrollView
{
[UIView animateWithDuration:0.3
delay:0
options:UIViewAnimationOptionAllowUserInteraction|UIViewAnimationOptionCurveEaseOut|UIViewAnimationOptionBeginFromCurrentState
animations:^{
if (down) {
// snap down
scrollView.contentOffset = CGPointMake(0, -kTopViewHeight);
scrollView.contentInset = UIEdgeInsetsMake(kTopViewHeight, 0, 0, 0);
} else {
// snap up
scrollView.contentOffset = CGPointMake(0, 0);
scrollView.contentInset = UIEdgeInsetsZero;
}
}
completion:nil];
}

Answer 1

//paging for data you can use this spinner
spinner = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
[spinner stopAnimating];
spinner.hidesWhenStopped = NO;
spinner.frame = CGRectMake(0, 0, 320, 44);
tblView.tableFooterView = spinner;
tblView.tableFooterView.hidden = YES;
#pragma mark Table pull to refresh data....
- (void)scrollViewDidEndDragging:(UIScrollView *)aScrollView
willDecelerate:(BOOL)decelerate{
CGPoint offset = aScrollView.contentOffset;
CGRect bounds = aScrollView.bounds;
CGSize size = aScrollView.contentSize;
UIEdgeInsets inset = aScrollView.contentInset;
float y = offset.y + bounds.size.height - inset.bottom;
float h = size.height;
float reload_distance = 50;
if(y > h + reload_distance && _nextPage) {
NSLog(#"load more data");
tblView.tableFooterView.hidden = NO;
// index for new page of data will increment here
index = index + 1;
[spinner startAnimating];
[self performSelector:#selector(requestData) withObject:nil afterDelay:1.0f];
}
}
// when you request for data and wants to stop spinner
CGPoint offset = tblView.contentOffset;
// if new page is there set bool
_nextPage = YES;
// want to remove spinner
tblView.tableFooterView.hidden = YES;
[spinner stopAnimating];
[tblView setContentOffset:offset animated:NO];