Locking a UISearchBar to the top of a UITableView like Game Center
There's this cool feature in the UITableViews in Game Center and the search bars they have at their tops. Unlike apps where the search bar is placed in the table header view (so it counts as a standard table cell), instead, it seems to be bolted to the parent navigation bar above it. So when scrolling the table, the search bar does indeed move, but if you scroll above the boundaries of the table, the search bar never stops touching the navigation bar.
Does anyone know how this might have been done? I was wondering if Apple maybe placed both the search bar and the table in a parent scroll view, but I'm wondering if it may be simpler than that.
Bob's answer is reversed: it ought to be MIN(0, scrollView.contentOffset.y).
Also, in order to properly support resizing (which would occur when rotated), the other frame values should be reused.
-(void)scrollViewDidScroll:(UIScrollView *)scrollView
{
UISearchBar *searchBar = searchDisplayController.searchBar;
CGRect rect = searchBar.frame;
rect.origin.y = MIN(0, scrollView.contentOffset.y);
searchBar.frame = rect;
}
You could put the searchBar in the table header and implement the - (void)scrollViewDidScroll:(UIScrollView *)scrollView delegate method for the tableView. Doing something like this should work:
-(void) scrollViewDidScroll:(UIScrollView *)scrollView {
searchBar.frame = CGRectMake(0,MAX(0,scrollView.contentOffset.y),320,44);
}
If you used the searchDisplayController, you would access the searchbar using self.searchDisplayController.searchbar.
在Swift 2.1和iOS 9.2.1中
let searchController = UISearchController(searchResultsController: nil)
override func viewDidLoad() {
/* Search controller parameters */
searchController.searchResultsUpdater = self // This protocol allows your class to be informed as text changes within the UISearchBar.
searchController.dimsBackgroundDuringPresentation = false // In this instance,using current view to show the results, so do not want to dim current view.
definesPresentationContext = true // ensure that the search bar does not remain on the screen if the user navigates to another view controller while the UISearchController is active.
let tableHeaderView: UIView = UIView.init(frame: searchController.searchBar.frame)
tableHeaderView.addSubview(searchController.searchBar)
self.tableView.tableHeaderView = tableHeaderView
}
override func scrollViewDidScroll(scrollView: UIScrollView) {
let searchBar:UISearchBar = searchController.searchBar
var searchBarFrame:CGRect = searchBar.frame
if searchController.active {
searchBarFrame.origin.y = 10
}
else {
searchBarFrame.origin.y = max(0, scrollView.contentOffset.y + scrollView.contentInset.top)
}
searchController.searchBar.frame = searchBarFrame
}