使用 NSMetadataQuery 搜索文件什么都不做 [英] Searching for files using NSMetadataQuery does simply nothing

问题描述

我尝试使用 NSMetadataQuery 和 NSPredicate 来搜索文件.经过几个小时的尝试和搜索解决方案(我是 swift 的新手)，我有一个小例子.它编译得很好，但结果为零.我尝试了不同的谓词，但最终 metadataQuery.resultCount 始终为 0.任何人都知道出了什么问题?

I try to use NSMetadataQuery and NSPredicate to search for files. After several hours of trying and searching for solutions (I'm new to swift) I have a small example. It compiles fine but the results are zero. I tried different predicates but at the end metadataQuery.resultCount is always 0. Anyone has an idea whats going wrong?

class AppDelegate: NSObject, NSApplicationDelegate {
var metadataQuery: NSMetadataQuery!
var metadataQueryDidUpdateObserver: AnyObject?
var metadataQueryDidFinishGatheringObserver: AnyObject?


@IBOutlet weak var window: NSWindow!

func applicationDidFinishLaunching(aNotification: NSNotification) {

    NSNotificationCenter.defaultCenter().addObserver(self, selector: "initalGatherComplete:", name: NSMetadataQueryDidFinishGatheringNotification, object: nil)

    metadataQuery = NSMetadataQuery()
    metadataQuery.searchScopes = [NSMetadataQueryIndexedLocalComputerScope]
    metadataQuery.predicate = NSPredicate(format: "%K LIKE '*'", NSMetadataItemFSNameKey)
    metadataQuery.startQuery()

}

func initalGatherComplete(notification: NSNotification) {
    metadataQuery.stopQuery()

    let resultCounter = metadataQuery.resultCount
    NSLog("%lu", resultCounter)

    NSNotificationCenter.defaultCenter().removeObserver(self, name: NSMetadataQueryDidFinishGatheringNotification, object: nil)
}

最后但并非最不重要的一点:当前谓词应列出所有文件，但最后谓词应仅列出应用程序.创建这样的谓词的最佳实践是什么?我计划过滤扩展名 .app 但也许有更好的方法?

And last but not least: the current predicate should list all files, but at the end the predicate should only list applications. whats the best practice to create such a predicate? I planned to filter for the extension .app but perhaps there is a better way?

谢谢！

推荐答案

检查您的 谓词语法.LIKE 运算符不适用于 NSMetadataQuery 谓词搜索(实际上 NSPredicate 在Spotlight 元数据搜索的上下文.)

Check your predicate syntax. The LIKE operator isn't available for NSMetadataQuery predicate searches (in fact NSPredicate uses a quite similar but actually different set of operators and behavior in the context of Spotlight metadata searches.)

NSMetadataQuery 的 glob 搜索语法只使用等号:

NSMetadataQuery's syntax for glob searches just uses an equals sign:

NSPredicate(format: "%K ==[cd] '*'", NSMetadataItemFSNameKey)

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