Objective-C full text search engine.
This project provides a way to integrate full-text search capabilities into your iOS or OS X project. First, it provides a protocol-based API for a simple text indexing and search framework. Second, it provides a CLucene based implementation of that framework.
The following snippet shows how the API works. The CLuceneSearchService reference
is the only CLucene-specific portion of the code:
id<BRSearchService> service = [[CLuceneSearchService alloc] initWithIndexPath:@"/some/path"];
// add a document to the index
id<BRIndexable> doc = [[BRSimpleIndexable alloc] initWithIdentifier:@"1" data:@{
kBRSearchFieldNameTitle : @"Special document",
kBRSearchFieldNameValue : @"This is a long winded note with really important details in it."
}];
NSError *error = nil;
[service addObjectToIndexAndWait:doc error:&error];
// search for documents and log contents of each result
id<BRSearchResults> results = [service search:@"special"];
[results iterateWithBlock:^(NSUInteger index, id<BRSearchResult>result, BOOL *stop) {
NSLog(@"Found result: %@", [result dictionaryRepresentation]);
}];There are some sample projects included in the source distribution:
- SampleCocoaPodsProject - a Core Data based iOS application using CocoaPods integration
- SampleOSXCocoaPodsProject - a Core Data based OS X application using CocoaPods integration
The BRSearchService API supports NSPredicate based queries:
- (id<BRSearchResults>)searchWithPredicate:(NSPredicate *)predicate
sortBy:(NSString *)sortFieldName
sortType:(BRSearchSortType)sortType
ascending:(BOOL)ascending;This method of querying can be quite useful when constructing a query out of user-supplied query text.
For example, you could support prefix based queries (for example, searching for ca* to match cat):
// get query as string, from text field for Example
NSString * query = ...;
static NSExpression *ValueExpression;
if ( ValueExpression == nil ) {
ValueExpression = [NSExpression expressionForKeyPath:kBRSearchFieldNameValue];
}
NSArray *tokens = [[query stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]]
componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
NSMutableArray *predicates = [NSMutableArray arrayWithCapacity:([tokens count] * 2)];
for ( NSString *token in tokens ) {
[predicates addObject:[NSComparisonPredicate predicateWithLeftExpression:ValueExpression
rightExpression:[NSExpression expressionForConstantValue:token]
modifier:NSDirectPredicateModifier
type:NSLikePredicateOperatorType
options:0]];
[predicates addObject:[NSComparisonPredicate predicateWithLeftExpression:ValueExpression
rightExpression:[NSExpression expressionForConstantValue:token]
modifier:NSDirectPredicateModifier
type:NSBeginsWithPredicateOperatorType
options:0]];
}
NSPredicate *predicateQuery = [NSCompoundPredicate orPredicateWithSubpredicates:predicates];
searchResults = [searchService searchWithPredicate:predicateQuery sortBy:nil sortType:0 ascending:NO];When indexing many documents at once, BRSearchService provides a set of methods specifically designed
for efficient bulk operations:
// bulk block callback function.
typedef void (^BRSearchServiceIndexUpdateBlock)(id <BRIndexUpdateContext> updateContext);
// perform a bulk operation, calling the passed on block
- (void)bulkUpdateIndex:(BRSearchServiceIndexUpdateBlock)updateBlock
queue:(dispatch_queue_t)finishedQueue
finished:(BRSearchServiceUpdateCallbackBlock)finished;
// from within the block, the following methods can be used (notice the updateContext parameter):
- (void)addObjectToIndex:(id <BRIndexable> )object context:(id <BRIndexUpdateContext> )updateContext;
- (int)removeObjectFromIndex:(BRSearchObjectType)type withIdentifier:(NSString *)identifier
context:(id <BRIndexUpdateContext> )updateContext;
- (int)removeObjectsFromIndexMatchingPredicate:(NSPredicate *)predicate
context:(id <BRIndexUpdateContext> )updateContext;
- (int)removeAllObjectsFromIndex:(id <BRIndexUpdateContext> )updateContext;Here's an example of a bulk operation that adds 100,000 documents to the index; notice the strategic
use of @autoreleasepool to keep a lid on memory use during the operation:
id<BRSearchService> service = ...;
[service bulkUpdateIndex:^(id<BRIndexUpdateContext> updateContext) {
if ( [updateContext respondsToSelector:@selector(setOptimizeWhenDone:)] ) {
updateContext.optimizeWhenDone = YES;
}
// add a bunch of documents to the index, in small autorelease batches
for ( int i = 0; i < 100000; i+= 1000 ) {
@autoreleasepool {
for ( int j = 0; j < 1000; j++ ) {
id<BRIndexable> doc = ...;
[service addObjectToIndex:doc context:updateContext];
}
}
}
} queue:dispatch_get_main_queue() finished:^(int updateCount, NSError *error) {
// all finished here
}];It's pretty easy to integrate BRFullTextSearch with Core Data, to maintain a search
index while changes are persisted in Core Data. One way is to listen for the
NSManagedObjectContextDidSaveNotification notification and process Core Data
changes as index delete and update operations. The SampleCocoaPodsProject iOS project
contains an example of this integration. The app allows you to create small sticky
notes and search the text of those notes. See the
CoreDataManager class in the sample
project, whose maintainSearchIndexFromManagedObjectDidSave: method handles this.
The SampleOSXCocoaPodsProject OS X project also contains an example of this integration. See the CoreDataManager class in that project for details.
You can integrate BRFullTextSearch via CocoaPods, or manually as either a dependent project or static framework.
Install CocoaPods if not already available:
$ [sudo] gem install cocoapods
$ pod setupChange to the directory of your Xcode project, and create a file named Podfile with
contents similar to this:
platform :ios, '5.0'
pod 'BRFullTextSearch', '~> 2.0'
Install into your project:
$ pod installOpen your project in Xcode using the .xcworkspace file CocoaPods generated.
Note: the use_frameworks! option is not supported, see #4. Any pull requests
to allow for building as a dynamic framework are very welcome!
Using this approach you'll build a static library framework that you can manually integrate into your own project.
The BRFullTextSearch Xcode project includes a target called
BRFullTextSearch.framework that builds a static library framework. Build that
target, which will produce a Framework/Release/BRFullTextSearch.framework bundle at
the root project directory. Copy that framework into your project and add it as a
build dependency.
You must also add the following linker build dependencies, which you can do by clicking the + button in the Link Binary With Libraries section of the Build Phases tab in the project settings:
- libz
- libc++
Next, add -ObjC as an Other Linker Flags build setting. If you do not have any
C++ sources in your project, you probably also need to add -stdlib=libc++ to
this setting as well.
Finally, you'll need to add the path to the directory containing the
BRFullTextSearch.framework bundle as a Framework Search Paths value in the
Build Settings tab of the project settings.
The SampleStaticLibraryProject included in this repository is an example project set up using the static library framework integration approach. You must build BRFullTextSearch.framework first, then open this project. When you run the project, it will index a set of documents using some Latin text. You can then search for latin words using a simple UI.