Programming the iPhone : Standard Control Types (part 5) - Search Bars

5. Search Bars

Search bars gather user input and allow applications to respond to that input in real time. A simple example is using a search bar at the top of the screen to filter a list of records in a table view based on string pattern matching. To use a search bar, you must create an instance of UISearchBar and add it to your view. You must also set the delegate property of the UISearchBar instance to an object that implements the UISearchBarDelegate protocol. Each method in the UISearchBarDelegate protocol handles a different user action. For example, you can implement the searchBar:textDidChange: method to develop progressive searches (a.k.a., auto-complete searches), or you can choose to execute searches only when editing ends using the searchBarSearchButtonClicked: and searchBarTextDidEndEditing: methods.

The TileSearchViewController class is from an example application that filters colored tiles based on color names input by a user:

#import "TileSearchViewController.h"
#import "Board.h"

@implementation TileSearchViewController

- (void)viewDidLoad
{
	searchBar = [[UISearchBar alloc] 
		initWithFrame:CGRectMake(0.0, 0.0, 320.0, 44.0)];
	searchBar.autocorrectionType = UITextAutocorrectionTypeNo;
	searchBar.autocapitalizationType = UITextAutocapitalizationTypeNone;
	searchBar.showsCancelButton = NO;

	//	Set myself as the delegate of the search bar.
	searchBar.delegate = self;
	
	[self.view addSubview:searchBar];
	if(board == nil) board = [[Board alloc]
		initWithFrame:CGRectMake(0.0, 45.0, 320.0, 415.0)];
	[self.view addSubview:board];
}


#pragma mark UISearchBarDelegate methods
- (void)searchBarTextDidBeginEditing:(UISearchBar *)theSearchBar
{
	//	Show cancel button while editing
	searchBar.showsCancelButton = YES;
}

- (void)searchBarTextDidEndEditing:(UISearchBar *)theSearchBar
{
	//	Hide cancel button when editing ends
	searchBar.showsCancelButton = NO;
}

- (void)searchBar:(UISearchBar *)theSearchBar
	textDidChange:(NSString *)searchText
{
	[board filterForColorName:searchText];
}

- (void)searchBarCancelButtonClicked:(UISearchBar *)theSearchBar
{
	//	Repopulate the last color unless the user cleared the search
	if (theSearchBar.text.length > 0){
		searchBar.text = lastSearch;
	}else{
		searchBar.text = @"";
	}
	
	[searchBar resignFirstResponder];
}

- (void)searchBarSearchButtonClicked:(UISearchBar *)theSearchBar
{
	[lastSearch release];
	lastSearch = [theSearchBar.text copy];
	[searchBar resignFirstResponder];
}


- (void)dealloc
{
	[searchBar release];
	[board release];
	[lastSearch release];
	[super dealloc];
}

@end


					  

Figure 9 shows a screenshot of the TileSearch example application.

Figure 9. The TileSearch example application