ios - 大括号语句 block 是 Swift 2 中未使用的闭包

Question

override func viewDidAppear(animated: Bool) {
super.viewDidAppear(animated)

if let directoryURL = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)[0] as? NSURL {

    let urls = try NSFileManager.defaultManager().contentsOfDirectoryAtURL(directoryURL, includingPropertiesForKeys: nil, options: NSDirectoryEnumerationOptions.SkipsHiddenFiles)
    //Error: Errors thrown from here are not handled

    catch let error as NSError {
    //Error: Consecutive statements on a line must be separated by ';'
    //Error: Braced block of statements is an unused closure
    //Error: Expected expression

        print("There's an error")
    }

    downloadedPhotoURLs = urls as [NSURL]
    collectionView!.reloadData()
}
}

这个错误很奇怪，try/catch 模式似乎没有任何问题，因为它在我的其他项目中工作正常，但我不知道为什么 Xcode 无法识别它。

Answer 1

你忘了使用do:

if let directoryURL = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)[0] as? NSURL {
    do {
        let urls = try NSFileManager.defaultManager().contentsOfDirectoryAtURL(directoryURL, includingPropertiesForKeys: nil, options: NSDirectoryEnumerationOptions.SkipsHiddenFiles)
        downloadedPhotoURLs = urls as [NSURL]
        collectionView!.reloadData()
    } catch let error as NSError {
        print(error)
    }
}