Question

我从我的数据库peopleArray获得了一个非常大的数组，其中包含我应用的所有用户。该数组用于搜索朋友。我的问题是，当用户开始在搜索栏中输入时，应用程序通常会在显示搜索到的用户之前暂停一段时间。

 #pragma mark - SEARCH BAR

- (void) filterContententForSearchText: (NSString *) searchText scope:(NSString *) scope{
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"%K beginsWith[cd] %@",@"Name", searchText ];
self.searchArray = [self.peopleArray filteredArrayUsingPredicate:predicate];
}

- (BOOL) searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchString:(NSString *)searchString{
[self filterContententForSearchText:searchString scope:[[self.searchDisplayController.searchBar scopeButtonTitles] objectAtIndex:[self.searchDisplayController.searchBar selectedScopeButtonIndex]]];
return YES;
}

- (void) searchDisplayControllerDidEndSearch:(UISearchDisplayController *)controller{
[self.tableView reloadData];
}

我想在后台执行此操作，因此我可以在加载时在tableView中放置UIActivityIndicator，但不确定在后台实现哪个方法或如何实现该方法。

Answer 1

首先，我建议使用一个计时器，这样你就不会在每个按键上重新加载用户。我这样做：

//I put this in my private @interface
@property (nonatomic, strong) NSTimer *searchTimer;

//Then we have the method called on keypress
- (void)whateverMethodIsCalledOnKeypress {
    [self.searchTimer invalidate];
    self.searchTimer = nil;
    //put some logic that returns out of the function for empty strings etc. here
    self.searchTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(runSearch) userInfo:nil repeats:NO];
}

- (void)runSearch {
    //do whatever you need to run the search this way
    //it's only ever done at most once per second
    //so fast typists don't overload the processor
}

这里有一些代码可以进行异步过滤。

//Show your activity indicator
dispatch_async(dispatch_get_global_queue(0,0), ^{
    //call whatever you need to do on the filtering here
    dispatch_async(dispatch_get_main_queue(), ^{
        //Hide your activity indicator
        [self.tableView reloadData];
    });
});

在后台线程中执行数组搜索？

1 个答案: