Move a UIView based on the content offset for UIScrollView - ios

Question

I am trying to pull down a UIView (Like a Pull Down Menu) when the user scrolls below a Y-offset of 0.0 in the UITable View. If the user pulls down below -80.0 Y-Offset, then the PullDownMenu locks itself , until the User scrolls the other way.
My implementation for just the UITableView's ScrollView is as follows : [lock:false initially]
-(void)scrollViewDidScroll:(UIScrollView *)scrollView {
if(isChangingOffset)
return;
if(resetDrag)
{
[self setScrollViewOffset:scrollView offsetTo:CGPointMake(0, -80.0)];
resetDrag = false;
}
float xx = scrollView.contentOffset.y;
NSLog(#"Offset :%f",xx);
if(xx - begginOffset > 0.0 && lock && !doneDragging)
{
offsetChange = xx - begginOffset;
begginOffset = xx;
lock = false;
[self setScrollViewOffset:scrollView offsetTo:CGPointMake(0, -80.0)];
}
if(lock){
[self setScrollViewOffset:scrollView offsetTo:CGPointMake(0, -80.0)];
}
if(xx <=-80.0)
{
[self setScrollViewOffset:scrollView offsetTo:CGPointMake(0, -80.0)];
lock = true;
}
}
- (void)setScrollViewOffset:(UIScrollView *)scrollView offsetTo:(CGPoint)offset{
- (void)setScrollViewOffset:(UIScrollView *)scrollView offsetTo:(CGPoint)offset{
isChangingOffset = true;
scrollView.contentOffset = CGPointMake(0, -80.0);
isChangingOffset = false;
}
-(void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
-(void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
float x = scrollView.contentOffset.y;
begginOffset = x;
doneDragging = false;
if(lock){
resetDrag = true;
}
}
-(void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
-(void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{
doneDragging = true;
}
Here is a working video of how it looks : Video
The blue color is a UIView that I have added as a subview in the UITableView.
My problem is , I am trying to pull down a UIView,lets call it menuView (that is not a subview of the tableView) based on the UITableView's contentOffset. I could have simply added the menuView in the UITableView like I added the blue color view. But that is only accessible via the table, that is when I scroll to the top and drag it down. But I want the menuView to be 'pull-able' like the notification center at any time.
On using the Y-contentOffset of scroll view, the menuview pull down animation is not smooth. And it stops midway or goes too low. It is jerky and not always the same. How can I implement this ?

Answer 1

Here the sample code for your UIScrollView :
ViewController.h
#interface ViewController: UIViewController {
UIScrollView *scrollView;
}
#property (nonatomic, strong) IBOutlet UIScrollView *scrollView;
ViewController.m
#implementation ViewController
#synthesize scrollView;
- (void)viewDidLoad
{
[super viewDidLoad];
[self scrollView];
}
- (void)scrollText{
[scrollView setContentSize:CGSizeMake(320, 800)];
scrollView.scrollEnabled = YES;
scrollView.pagingEnabled = YES;
scrollView.clipsToBounds = YES;
}
And iside you can put wat you want, from code or interface builder.
For a PullDownMenu you can see this GitHub:
MBPullDownController
Hope this help you and simplify your code ;)