Macos 聚光灯查询

我正在为LEOPARD（10.5）做一个小项目，我是Objective-C编程的新手。我一直在网上搜索一些教程，但我还是很困惑！我需要使用Leopard的spotlight功能来搜索用户计算机上安装的每个.app文件。我还需要它的名称，路径和图标。所有查询的数据必须保存在文本文件中。我该怎么做？？？

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谢谢大家!

定义查询，并观察查询终止

- (void)searchApplications {
    NSMetadataQuery *query = [[NSMetadataQuery alloc] init];
    query.predicate = [NSPredicate predicateWithFormat:@"kMDItemContentTypeTree == 'com.apple.application'"];

    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(queryDidFinish:)
                                                 name:NSMetadataQueryDidFinishGatheringNotification
                                               object:query];

    [query startQuery];
}

在查询终止函数中，循环遍历结果并提取所需的数据

- (void)queryDidFinish:(NSNotification *)notification {

    NSMetadataQuery *query = (NSMetadataQuery *)[notification object];

    [query stopQuery];

    NSMutableArray *paths = [NSMutableArray array];

    for(NSMetadataItem *mdItem in query.results) {
        NSString *name = [mdItem valueForAttribute:(NSString *)kMDItemDisplayName];
        NSString *path = [mdItem valueForAttribute:(NSString *)kMDItemPath];
        NSImage *icon = [[NSWorkspace sharedWorkspace] iconForFile:path];

        [paths addObject:path];
    }

    [query release];

    [paths writeToFile:@"/tmp/applications.txt" atomically:YES];
}