objective-c - 在后台线程上搜索

Question

我试图在我的 iPhone 应用程序中搜索几千个对象，但是搜索非常滞后 - 每次按键后，UI 会卡住 1 - 2 秒。为防止这种情况，我必须在后台线程上执行搜索。

我想知道是否有人有一些关于在后台线程上搜索的技巧？我读了一点 NSOperation 并在网上搜索，但没有找到任何有用的东西。

Answer 1

尝试使用 NSOperationQueue作为 View Controller 中的实例变量。

@interface SearchViewController : UIViewController {
    NSOperationQueue *searchQueue;
    //other awesome ivars...
}
//blah blah
@end

@implementation SearchViewController

- (id)initWithNibName:(NSString *)nibName bundle:(NSBundle *)nibBundle {
   if((self = [super initWithNibName:nibName bundle:nibBundle])) {
      //perform init here..
      searchQueue = [[NSOperationQueue alloc] init];
   }
   return self;
}

- (void) beginSearching:(NSString *) searchTerm {
   NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
   //perform search...
   [self.searchDisplayController.searchResultsTableView reloadData];
   [pool drain];

}

- (void)searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText
   /* 
      Cancel any running operations so we only have one search thread 
      running at any given time..
   */
   [searchQueue cancelAllOperations];
   NSInvocationOperation *op = [[NSInvocationOperation alloc] initWithTarget:self 
                                                                    selector:@selector(beginSearching:)
                                                                      object:searchText];
   [searchQueue addOperation:op];
   [op release];  
}

- (void) dealloc {
  [searchQueue release];
  [super dealloc];
}
@end